From a811bf652adb3066d68d588232e0ce983dbf0fa2 Mon Sep 17 00:00:00 2001
From: Elliot Winkler <elliot.winkler@gmail.com>
Date: Tue, 21 Jan 2025 10:52:46 -0700
Subject: [PATCH 1/3] createServicePolicy: Convert callbacks to methods
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Both RetryPolicy and CircuitBreakerPolicy from the Cockatiel library
allow for listening for events using `on*` methods. Our "service policy"
allows for listening to some of the same events as well as the
"degraded" event. For parity with Cockatiel — and for easier use in
general — this commit removes the callbacks that `createServicePolicy`
takes and replaces them with `on*` methods.
---
 packages/controller-utils/CHANGELOG.md        |   6 +-
 .../src/create-service-policy.test.ts         | 529 +++++++++---------
 .../src/create-service-policy.ts              | 144 +++--
 packages/controller-utils/src/index.ts        |   5 +-
 4 files changed, 373 insertions(+), 311 deletions(-)

diff --git a/packages/controller-utils/CHANGELOG.md b/packages/controller-utils/CHANGELOG.md
index 8ef13e469f5..ef8364c1754 100644
--- a/packages/controller-utils/CHANGELOG.md
+++ b/packages/controller-utils/CHANGELOG.md
@@ -9,8 +9,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
-- Add `createServicePolicy` function to assist with reducing boilerplate for service classes ([#5154](https://github.com/MetaMask/core/pull/5154), [#5143](https://github.com/MetaMask/core/pull/5143), [#5149](https://github.com/MetaMask/core/pull/5149))
-  - Also add `DEFAULT_CIRCUIT_BREAK_DURATION`, `DEFAULT_DEGRADED_THRESHOLD`, `DEFAULT_MAX_CONSECUTIVE_FAILURES`, and `DEFAULT_MAX_RETRIES` constants and `IServicePolicy` type
+- Add utility function for reducing boilerplate for service classes ([#5154](https://github.com/MetaMask/core/pull/5154), [#5143](https://github.com/MetaMask/core/pull/5143), [#5149](https://github.com/MetaMask/core/pull/5149), [#5188](https://github.com/MetaMask/core/pull/5188))
+  - Add function `createServicePolicy`
+  - Add constants `DEFAULT_CIRCUIT_BREAK_DURATION`, `DEFAULT_DEGRADED_THRESHOLD`, `DEFAULT_MAX_CONSECUTIVE_FAILURES`, and `DEFAULT_MAX_RETRIES`
+  - Add types `ServicePolicy` and `CreateServicePolicyOptions`
 
 ## [11.4.5]
 
diff --git a/packages/controller-utils/src/create-service-policy.test.ts b/packages/controller-utils/src/create-service-policy.test.ts
index 0474647cea4..0b5894dad8c 100644
--- a/packages/controller-utils/src/create-service-policy.test.ts
+++ b/packages/controller-utils/src/create-service-policy.test.ts
@@ -43,58 +43,62 @@ describe('createServicePolicy', () => {
       expect(mockService).toHaveBeenCalledTimes(1);
     });
 
-    it('does not call the onBreak callback, since the circuit never opens', async () => {
+    it('does not call the listener passed to onBreak, since the circuit never opens', async () => {
       const mockService = jest.fn(() => ({ some: 'data' }));
-      const onBreak = jest.fn();
-      const policy = createServicePolicy({ onBreak });
+      const onBreakListener = jest.fn();
+      const policy = createServicePolicy();
+      policy.onBreak(onBreakListener);
 
       await policy.execute(mockService);
 
-      expect(onBreak).not.toHaveBeenCalled();
+      expect(onBreakListener).not.toHaveBeenCalled();
     });
 
     describe(`using the default degraded threshold (${DEFAULT_DEGRADED_THRESHOLD})`, () => {
-      it('does not call the onDegraded callback if the service execution time is below the threshold', async () => {
+      it('does not call the listener passed to onDegraded if the service execution time is below the threshold', async () => {
         const mockService = jest.fn(() => ({ some: 'data' }));
-        const onDegraded = jest.fn();
-        const policy = createServicePolicy({ onDegraded });
+        const onDegradedListener = jest.fn();
+        const policy = createServicePolicy();
+        policy.onDegraded(onDegradedListener);
 
         await policy.execute(mockService);
 
-        expect(onDegraded).not.toHaveBeenCalled();
+        expect(onDegradedListener).not.toHaveBeenCalled();
       });
 
-      it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
+      it('calls the listener passed to onDegraded once if the service execution time is beyond the threshold', async () => {
         const delay = DEFAULT_DEGRADED_THRESHOLD + 1;
         const mockService = jest.fn(() => {
           return new Promise((resolve) => {
             setTimeout(() => resolve({ some: 'data' }), delay);
           });
         });
-        const onDegraded = jest.fn();
-        const policy = createServicePolicy({ onDegraded });
+        const onDegradedListener = jest.fn();
+        const policy = createServicePolicy();
+        policy.onDegraded(onDegradedListener);
 
         const promise = policy.execute(mockService);
         clock.tick(delay);
         await promise;
 
-        expect(onDegraded).toHaveBeenCalledTimes(1);
+        expect(onDegradedListener).toHaveBeenCalledTimes(1);
       });
     });
 
     describe('using a custom degraded threshold', () => {
-      it('does not call the onDegraded callback if the service execution time below the threshold', async () => {
+      it('does not call the listener passed to onDegraded if the service execution time below the threshold', async () => {
         const degradedThreshold = 2000;
         const mockService = jest.fn(() => ({ some: 'data' }));
-        const onDegraded = jest.fn();
-        const policy = createServicePolicy({ degradedThreshold, onDegraded });
+        const onDegradedListener = jest.fn();
+        const policy = createServicePolicy({ degradedThreshold });
+        policy.onDegraded(onDegradedListener);
 
         await policy.execute(mockService);
 
-        expect(onDegraded).not.toHaveBeenCalled();
+        expect(onDegradedListener).not.toHaveBeenCalled();
       });
 
-      it('calls the onDegraded callback once if the service execution time beyond the threshold', async () => {
+      it('calls the listener passed to onDegraded once if the service execution time beyond the threshold', async () => {
         const degradedThreshold = 2000;
         const delay = degradedThreshold + 1;
         const mockService = jest.fn(() => {
@@ -102,14 +106,15 @@ describe('createServicePolicy', () => {
             setTimeout(() => resolve({ some: 'data' }), delay);
           });
         });
-        const onDegraded = jest.fn();
-        const policy = createServicePolicy({ degradedThreshold, onDegraded });
+        const onDegradedListener = jest.fn();
+        const policy = createServicePolicy({ degradedThreshold });
+        policy.onDegraded(onDegradedListener);
 
         const promise = policy.execute(mockService);
         clock.tick(delay);
         await promise;
 
-        expect(onDegraded).toHaveBeenCalledTimes(1);
+        expect(onDegradedListener).toHaveBeenCalledTimes(1);
       });
     });
   });
@@ -149,37 +154,37 @@ describe('createServicePolicy', () => {
         expect(mockService).toHaveBeenCalledTimes(1);
       });
 
-      it('does not call the onRetry callback', async () => {
+      it('does not call the listener passed to onRetry', async () => {
         const error = new Error('failure');
         const mockService = jest.fn(() => {
           throw error;
         });
-        const onRetry = jest.fn();
+        const onRetryListener = jest.fn();
         const policy = createServicePolicy({
           retryFilterPolicy: handleWhen(
             (caughtError) => caughtError.message !== 'failure',
           ),
-          onRetry,
         });
+        policy.onRetry(onRetryListener);
 
         const promise = policy.execute(mockService);
         await ignoreRejection(promise);
 
-        expect(onRetry).not.toHaveBeenCalled();
+        expect(onRetryListener).not.toHaveBeenCalled();
       });
 
-      it('does not call the onBreak callback', async () => {
+      it('does not call the listener passed to onBreak', async () => {
         const error = new Error('failure');
         const mockService = jest.fn(() => {
           throw error;
         });
-        const onBreak = jest.fn();
+        const onBreakListener = jest.fn();
         const policy = createServicePolicy({
           retryFilterPolicy: handleWhen(
             (caughtError) => caughtError.message !== 'failure',
           ),
-          onBreak,
         });
+        policy.onBreak(onBreakListener);
 
         const promise = policy.execute(mockService);
         // It's safe not to await this promise; adding it to the promise queue
@@ -188,21 +193,21 @@ describe('createServicePolicy', () => {
         clock.runAllAsync();
         await ignoreRejection(promise);
 
-        expect(onBreak).not.toHaveBeenCalled();
+        expect(onBreakListener).not.toHaveBeenCalled();
       });
 
-      it('does not call the onDegraded callback', async () => {
+      it('does not call the listener passed to onDegraded', async () => {
         const error = new Error('failure');
         const mockService = jest.fn(() => {
           throw error;
         });
-        const onDegraded = jest.fn();
+        const onDegradedListener = jest.fn();
         const policy = createServicePolicy({
           retryFilterPolicy: handleWhen(
             (caughtError) => caughtError.message !== 'failure',
           ),
-          onDegraded,
         });
+        policy.onDegraded(onDegradedListener);
 
         const promise = policy.execute(mockService);
         // It's safe not to await this promise; adding it to the promise queue
@@ -211,7 +216,7 @@ describe('createServicePolicy', () => {
         clock.runAllAsync();
         await ignoreRejection(promise);
 
-        expect(onDegraded).not.toHaveBeenCalled();
+        expect(onDegradedListener).not.toHaveBeenCalled();
       });
     });
 
@@ -243,13 +248,14 @@ describe('createServicePolicy', () => {
           expect(mockService).toHaveBeenCalledTimes(1 + DEFAULT_MAX_RETRIES);
         });
 
-        it('calls the onRetry callback once per retry', async () => {
+        it('calls the listener passed to onRetry once per retry', async () => {
           const error = new Error('failure');
           const mockService = jest.fn(() => {
             throw error;
           });
-          const onRetry = jest.fn();
-          const policy = createServicePolicy({ onRetry });
+          const onRetryListener = jest.fn();
+          const policy = createServicePolicy();
+          policy.onRetry(onRetryListener);
 
           const promise = policy.execute(mockService);
           // It's safe not to await this promise; adding it to the promise queue is
@@ -258,7 +264,7 @@ describe('createServicePolicy', () => {
           clock.runAllAsync();
           await ignoreRejection(promise);
 
-          expect(onRetry).toHaveBeenCalledTimes(DEFAULT_MAX_RETRIES);
+          expect(onRetryListener).toHaveBeenCalledTimes(DEFAULT_MAX_RETRIES);
         });
 
         describe(`using the default max number of consecutive failures (${DEFAULT_MAX_CONSECUTIVE_FAILURES})`, () => {
@@ -278,13 +284,14 @@ describe('createServicePolicy', () => {
             await expect(promise).rejects.toThrow(error);
           });
 
-          it('does not call the onBreak callback, since the max number of consecutive failures is never reached', async () => {
+          it('does not call the listener passed to onBreak, since the max number of consecutive failures is never reached', async () => {
             const error = new Error('failure');
             const mockService = jest.fn(() => {
               throw error;
             });
-            const onBreak = jest.fn();
-            const policy = createServicePolicy({ onBreak });
+            const onBreakListener = jest.fn();
+            const policy = createServicePolicy();
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -293,16 +300,17 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await ignoreRejection(promise);
 
-            expect(onBreak).not.toHaveBeenCalled();
+            expect(onBreakListener).not.toHaveBeenCalled();
           });
 
-          it('calls the onDegraded callback once, since the circuit is still closed', async () => {
+          it('calls the listener passed to onDegraded once, since the circuit is still closed', async () => {
             const error = new Error('failure');
             const mockService = jest.fn(() => {
               throw error;
             });
-            const onDegraded = jest.fn();
-            const policy = createServicePolicy({ onDegraded });
+            const onDegradedListener = jest.fn();
+            const policy = createServicePolicy();
+            policy.onDegraded(onDegradedListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -311,7 +319,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await ignoreRejection(promise);
 
-            expect(onDegraded).toHaveBeenCalledTimes(1);
+            expect(onDegradedListener).toHaveBeenCalledTimes(1);
           });
         });
 
@@ -323,10 +331,8 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onBreak = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onBreak,
               });
 
               const promise = policy.execute(mockService);
@@ -338,17 +344,17 @@ describe('createServicePolicy', () => {
               await expect(promise).rejects.toThrow(error);
             });
 
-            it('does not call the onBreak callback', async () => {
+            it('does not call the listener passed to onBreak', async () => {
               const maxConsecutiveFailures = DEFAULT_MAX_RETRIES + 2;
               const error = new Error('failure');
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onBreak = jest.fn();
+              const onBreakListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onBreak,
               });
+              policy.onBreak(onBreakListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -357,20 +363,20 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onBreak).not.toHaveBeenCalled();
+              expect(onBreakListener).not.toHaveBeenCalled();
             });
 
-            it('calls the onDegraded callback once', async () => {
+            it('calls the listener passed to onDegraded once', async () => {
               const maxConsecutiveFailures = DEFAULT_MAX_RETRIES + 2;
               const error = new Error('failure');
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -379,7 +385,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
 
@@ -403,17 +409,17 @@ describe('createServicePolicy', () => {
               await expect(promise).rejects.toThrow(error);
             });
 
-            it('calls the onBreak callback once with the error', async () => {
+            it('calls the listener passed to onBreak once with the error', async () => {
               const maxConsecutiveFailures = DEFAULT_MAX_RETRIES + 1;
               const error = new Error('failure');
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onBreak = jest.fn();
+              const onBreakListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onBreak,
               });
+              policy.onBreak(onBreakListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -422,21 +428,21 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onBreak).toHaveBeenCalledTimes(1);
-              expect(onBreak).toHaveBeenCalledWith({ error });
+              expect(onBreakListener).toHaveBeenCalledTimes(1);
+              expect(onBreakListener).toHaveBeenCalledWith({ error });
             });
 
-            it('never calls the onDegraded callback, since the circuit is open', async () => {
+            it('never calls the listener passed to onDegraded, since the circuit is open', async () => {
               const maxConsecutiveFailures = DEFAULT_MAX_RETRIES + 1;
               const error = new Error('failure');
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -445,7 +451,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('throws a BrokenCircuitError instead of whatever error the service produces if the service is executed again', async () => {
@@ -498,17 +504,17 @@ describe('createServicePolicy', () => {
               );
             });
 
-            it('calls the onBreak callback once with the error', async () => {
+            it('calls the listener passed to onBreak once with the error', async () => {
               const maxConsecutiveFailures = DEFAULT_MAX_RETRIES;
               const error = new Error('failure');
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onBreak = jest.fn();
+              const onBreakListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onBreak,
               });
+              policy.onBreak(onBreakListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -517,21 +523,21 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onBreak).toHaveBeenCalledTimes(1);
-              expect(onBreak).toHaveBeenCalledWith({ error });
+              expect(onBreakListener).toHaveBeenCalledTimes(1);
+              expect(onBreakListener).toHaveBeenCalledWith({ error });
             });
 
-            it('never calls the onDegraded callback, since the circuit is open', async () => {
+            it('never calls the listener passed to onDegraded, since the circuit is open', async () => {
               const maxConsecutiveFailures = DEFAULT_MAX_RETRIES;
               const error = new Error('failure');
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -540,7 +546,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
           });
         });
@@ -582,11 +588,11 @@ describe('createServicePolicy', () => {
           const mockService = jest.fn(() => {
             throw error;
           });
-          const onRetry = jest.fn();
+          const onRetryListener = jest.fn();
           const policy = createServicePolicy({
             maxRetries,
-            onRetry,
           });
+          policy.onRetry(onRetryListener);
 
           const promise = policy.execute(mockService);
           // It's safe not to await this promise; adding it to the promise queue is
@@ -595,7 +601,7 @@ describe('createServicePolicy', () => {
           clock.runAllAsync();
           await ignoreRejection(promise);
 
-          expect(onRetry).toHaveBeenCalledTimes(maxRetries);
+          expect(onRetryListener).toHaveBeenCalledTimes(maxRetries);
         });
 
         describe(`using the default max number of consecutive failures (${DEFAULT_MAX_CONSECUTIVE_FAILURES})`, () => {
@@ -623,8 +629,9 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onBreak = jest.fn();
-              const policy = createServicePolicy({ maxRetries, onBreak });
+              const onBreakListener = jest.fn();
+              const policy = createServicePolicy({ maxRetries });
+              policy.onBreak(onBreakListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -633,7 +640,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onBreak).not.toHaveBeenCalled();
+              expect(onBreakListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once', async () => {
@@ -642,8 +649,9 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onDegraded = jest.fn();
-              const policy = createServicePolicy({ maxRetries, onDegraded });
+              const onDegradedListener = jest.fn();
+              const policy = createServicePolicy({ maxRetries });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -652,7 +660,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
 
@@ -680,8 +688,9 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onBreak = jest.fn();
-              const policy = createServicePolicy({ maxRetries, onBreak });
+              const onBreakListener = jest.fn();
+              const policy = createServicePolicy({ maxRetries });
+              policy.onBreak(onBreakListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -690,8 +699,8 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onBreak).toHaveBeenCalledTimes(1);
-              expect(onBreak).toHaveBeenCalledWith({ error });
+              expect(onBreakListener).toHaveBeenCalledTimes(1);
+              expect(onBreakListener).toHaveBeenCalledWith({ error });
             });
 
             it('never calls the onDegraded callback, since the circuit is open', async () => {
@@ -700,8 +709,9 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onDegraded = jest.fn();
-              const policy = createServicePolicy({ maxRetries, onDegraded });
+              const onDegradedListener = jest.fn();
+              const policy = createServicePolicy({ maxRetries });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -710,7 +720,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('throws a BrokenCircuitError instead of whatever error the service produces if the policy is executed again', async () => {
@@ -719,8 +729,7 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onDegraded = jest.fn();
-              const policy = createServicePolicy({ maxRetries, onDegraded });
+              const policy = createServicePolicy({ maxRetries });
 
               const firstExecution = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -765,8 +774,9 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onBreak = jest.fn();
-              const policy = createServicePolicy({ maxRetries, onBreak });
+              const onBreakListener = jest.fn();
+              const policy = createServicePolicy({ maxRetries });
+              policy.onBreak(onBreakListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -775,8 +785,8 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onBreak).toHaveBeenCalledTimes(1);
-              expect(onBreak).toHaveBeenCalledWith({ error });
+              expect(onBreakListener).toHaveBeenCalledTimes(1);
+              expect(onBreakListener).toHaveBeenCalledWith({ error });
             });
 
             it('never calls the onDegraded callback, since the circuit is open', async () => {
@@ -785,8 +795,9 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onDegraded = jest.fn();
-              const policy = createServicePolicy({ maxRetries, onDegraded });
+              const onDegradedListener = jest.fn();
+              const policy = createServicePolicy({ maxRetries });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -795,7 +806,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
           });
         });
@@ -830,12 +841,12 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onBreak = jest.fn();
+              const onBreakListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onBreak,
               });
+              policy.onBreak(onBreakListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -844,7 +855,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onBreak).not.toHaveBeenCalled();
+              expect(onBreakListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once', async () => {
@@ -854,12 +865,12 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -868,7 +879,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
 
@@ -901,12 +912,12 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onBreak = jest.fn();
+              const onBreakListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onBreak,
               });
+              policy.onBreak(onBreakListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -915,8 +926,8 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onBreak).toHaveBeenCalledTimes(1);
-              expect(onBreak).toHaveBeenCalledWith({ error });
+              expect(onBreakListener).toHaveBeenCalledTimes(1);
+              expect(onBreakListener).toHaveBeenCalledWith({ error });
             });
 
             it('never calls the onDegraded callback, since the circuit is open', async () => {
@@ -926,12 +937,12 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -940,7 +951,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('throws a BrokenCircuitError instead of whatever error the service produces if the policy is executed again', async () => {
@@ -1004,12 +1015,12 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onBreak = jest.fn();
+              const onBreakListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onBreak,
               });
+              policy.onBreak(onBreakListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1018,8 +1029,8 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onBreak).toHaveBeenCalledTimes(1);
-              expect(onBreak).toHaveBeenCalledWith({ error });
+              expect(onBreakListener).toHaveBeenCalledTimes(1);
+              expect(onBreakListener).toHaveBeenCalledWith({ error });
             });
 
             it('never calls the onDegraded callback, since the circuit is open', async () => {
@@ -1029,12 +1040,12 @@ describe('createServicePolicy', () => {
               const mockService = jest.fn(() => {
                 throw error;
               });
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1043,7 +1054,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await ignoreRejection(promise);
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
           });
         });
@@ -1096,8 +1107,9 @@ describe('createServicePolicy', () => {
             }
             throw new Error('failure');
           };
-          const onBreak = jest.fn();
-          const policy = createServicePolicy({ onBreak });
+          const onBreakListener = jest.fn();
+          const policy = createServicePolicy();
+          policy.onBreak(onBreakListener);
 
           const promise = policy.execute(mockService);
           // It's safe not to await this promise; adding it to the promise queue
@@ -1117,8 +1129,9 @@ describe('createServicePolicy', () => {
             }
             throw new Error('failure');
           };
-          const onBreak = jest.fn();
-          const policy = createServicePolicy({ onBreak });
+          const onBreakListener = jest.fn();
+          const policy = createServicePolicy();
+          policy.onBreak(onBreakListener);
 
           const promise = policy.execute(mockService);
           // It's safe not to await this promise; adding it to the promise queue
@@ -1127,7 +1140,7 @@ describe('createServicePolicy', () => {
           clock.runAllAsync();
           await promise;
 
-          expect(onBreak).not.toHaveBeenCalled();
+          expect(onBreakListener).not.toHaveBeenCalled();
         });
 
         describe(`using the default degraded threshold (${DEFAULT_DEGRADED_THRESHOLD})`, () => {
@@ -1140,8 +1153,9 @@ describe('createServicePolicy', () => {
               }
               throw new Error('failure');
             };
-            const onDegraded = jest.fn();
-            const policy = createServicePolicy({ onDegraded });
+            const onDegradedListener = jest.fn();
+            const policy = createServicePolicy();
+            policy.onDegraded(onDegradedListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1150,7 +1164,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await promise;
 
-            expect(onDegraded).not.toHaveBeenCalled();
+            expect(onDegradedListener).not.toHaveBeenCalled();
           });
 
           it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -1166,8 +1180,9 @@ describe('createServicePolicy', () => {
                 }
               });
             };
-            const onDegraded = jest.fn();
-            const policy = createServicePolicy({ onDegraded });
+            const onDegradedListener = jest.fn();
+            const policy = createServicePolicy();
+            policy.onDegraded(onDegradedListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1176,7 +1191,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await promise;
 
-            expect(onDegraded).toHaveBeenCalledTimes(1);
+            expect(onDegradedListener).toHaveBeenCalledTimes(1);
           });
         });
 
@@ -1191,11 +1206,11 @@ describe('createServicePolicy', () => {
               }
               throw new Error('failure');
             };
-            const onDegraded = jest.fn();
+            const onDegradedListener = jest.fn();
             const policy = createServicePolicy({
-              onDegraded,
               degradedThreshold,
             });
+            policy.onDegraded(onDegradedListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1204,7 +1219,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await promise;
 
-            expect(onDegraded).not.toHaveBeenCalled();
+            expect(onDegradedListener).not.toHaveBeenCalled();
           });
 
           it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -1221,11 +1236,11 @@ describe('createServicePolicy', () => {
                 }
               });
             };
-            const onDegraded = jest.fn();
+            const onDegradedListener = jest.fn();
             const policy = createServicePolicy({
-              onDegraded,
               degradedThreshold,
             });
+            policy.onDegraded(onDegradedListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1234,7 +1249,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await promise;
 
-            expect(onDegraded).toHaveBeenCalledTimes(1);
+            expect(onDegradedListener).toHaveBeenCalledTimes(1);
           });
         });
       });
@@ -1251,11 +1266,11 @@ describe('createServicePolicy', () => {
               }
               throw new Error('failure');
             };
-            const onBreak = jest.fn();
+            const onBreakListener = jest.fn();
             const policy = createServicePolicy({
               maxConsecutiveFailures,
-              onBreak,
             });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1276,11 +1291,11 @@ describe('createServicePolicy', () => {
               }
               throw new Error('failure');
             };
-            const onBreak = jest.fn();
+            const onBreakListener = jest.fn();
             const policy = createServicePolicy({
               maxConsecutiveFailures,
-              onBreak,
             });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1289,7 +1304,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await promise;
 
-            expect(onBreak).not.toHaveBeenCalled();
+            expect(onBreakListener).not.toHaveBeenCalled();
           });
 
           describe(`using the default degraded threshold (${DEFAULT_DEGRADED_THRESHOLD})`, () => {
@@ -1303,11 +1318,11 @@ describe('createServicePolicy', () => {
                 }
                 throw new Error('failure');
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1316,7 +1331,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -1333,11 +1348,11 @@ describe('createServicePolicy', () => {
                   }
                 });
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1346,7 +1361,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
 
@@ -1362,12 +1377,12 @@ describe('createServicePolicy', () => {
                 }
                 throw new Error('failure');
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onDegraded,
                 degradedThreshold,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1376,7 +1391,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -1394,12 +1409,12 @@ describe('createServicePolicy', () => {
                   }
                 });
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onDegraded,
                 degradedThreshold,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1408,7 +1423,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
         });
@@ -1424,11 +1439,11 @@ describe('createServicePolicy', () => {
               }
               throw new Error('failure');
             };
-            const onBreak = jest.fn();
+            const onBreakListener = jest.fn();
             const policy = createServicePolicy({
               maxConsecutiveFailures,
-              onBreak,
             });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1450,11 +1465,11 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onBreak = jest.fn();
+            const onBreakListener = jest.fn();
             const policy = createServicePolicy({
               maxConsecutiveFailures,
-              onBreak,
             });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1463,7 +1478,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await promise;
 
-            expect(onBreak).not.toHaveBeenCalled();
+            expect(onBreakListener).not.toHaveBeenCalled();
           });
 
           describe(`using the default degraded threshold (${DEFAULT_DEGRADED_THRESHOLD})`, () => {
@@ -1478,11 +1493,11 @@ describe('createServicePolicy', () => {
                 }
                 throw error;
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1491,7 +1506,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -1508,11 +1523,11 @@ describe('createServicePolicy', () => {
                   }
                 });
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1521,7 +1536,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
 
@@ -1538,12 +1553,12 @@ describe('createServicePolicy', () => {
                 }
                 throw error;
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onDegraded,
                 degradedThreshold,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1552,7 +1567,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -1570,12 +1585,12 @@ describe('createServicePolicy', () => {
                   }
                 });
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxConsecutiveFailures,
-                onDegraded,
                 degradedThreshold,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1584,7 +1599,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
         });
@@ -1601,11 +1616,11 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onBreak = jest.fn();
+            const onBreakListener = jest.fn();
             const policy = createServicePolicy({
               maxConsecutiveFailures,
-              onBreak,
             });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1630,11 +1645,11 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onBreak = jest.fn();
+            const onBreakListener = jest.fn();
             const policy = createServicePolicy({
               maxConsecutiveFailures,
-              onBreak,
             });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1643,8 +1658,8 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await ignoreRejection(promise);
 
-            expect(onBreak).toHaveBeenCalledTimes(1);
-            expect(onBreak).toHaveBeenCalledWith({ error });
+            expect(onBreakListener).toHaveBeenCalledTimes(1);
+            expect(onBreakListener).toHaveBeenCalledWith({ error });
           });
 
           it('does not call the onDegraded callback', async () => {
@@ -1658,11 +1673,11 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onDegraded = jest.fn();
+            const onDegradedListener = jest.fn();
             const policy = createServicePolicy({
               maxConsecutiveFailures,
-              onDegraded,
             });
+            policy.onDegraded(onDegradedListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1671,7 +1686,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await ignoreRejection(promise);
 
-            expect(onDegraded).not.toHaveBeenCalled();
+            expect(onDegradedListener).not.toHaveBeenCalled();
           });
 
           describe(`using the default circuit break duration (${DEFAULT_CIRCUIT_BREAK_DURATION})`, () => {
@@ -1808,8 +1823,9 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onBreak = jest.fn();
-            const policy = createServicePolicy({ maxRetries, onBreak });
+            const onBreakListener = jest.fn();
+            const policy = createServicePolicy({ maxRetries });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1818,7 +1834,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await promise;
 
-            expect(onBreak).not.toHaveBeenCalled();
+            expect(onBreakListener).not.toHaveBeenCalled();
           });
 
           describe(`using the default degraded threshold (${DEFAULT_DEGRADED_THRESHOLD})`, () => {
@@ -1833,8 +1849,9 @@ describe('createServicePolicy', () => {
                 }
                 throw error;
               };
-              const onDegraded = jest.fn();
-              const policy = createServicePolicy({ maxRetries, onDegraded });
+              const onDegradedListener = jest.fn();
+              const policy = createServicePolicy({ maxRetries });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1843,7 +1860,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -1860,8 +1877,9 @@ describe('createServicePolicy', () => {
                   }
                 });
               };
-              const onDegraded = jest.fn();
-              const policy = createServicePolicy({ maxRetries, onDegraded });
+              const onDegradedListener = jest.fn();
+              const policy = createServicePolicy({ maxRetries });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1870,7 +1888,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
 
@@ -1887,12 +1905,12 @@ describe('createServicePolicy', () => {
                 }
                 throw error;
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
-                onDegraded,
                 degradedThreshold,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1901,7 +1919,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -1919,12 +1937,12 @@ describe('createServicePolicy', () => {
                   }
                 });
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
-                onDegraded,
                 degradedThreshold,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -1933,7 +1951,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
         });
@@ -1972,8 +1990,9 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onBreak = jest.fn();
-            const policy = createServicePolicy({ maxRetries, onBreak });
+            const onBreakListener = jest.fn();
+            const policy = createServicePolicy({ maxRetries });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -1982,7 +2001,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await promise;
 
-            expect(onBreak).not.toHaveBeenCalled();
+            expect(onBreakListener).not.toHaveBeenCalled();
           });
 
           describe(`using the default degraded threshold (${DEFAULT_DEGRADED_THRESHOLD})`, () => {
@@ -1997,8 +2016,9 @@ describe('createServicePolicy', () => {
                 }
                 throw error;
               };
-              const onDegraded = jest.fn();
-              const policy = createServicePolicy({ maxRetries, onDegraded });
+              const onDegradedListener = jest.fn();
+              const policy = createServicePolicy({ maxRetries });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -2007,7 +2027,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -2024,8 +2044,9 @@ describe('createServicePolicy', () => {
                   }
                 });
               };
-              const onDegraded = jest.fn();
-              const policy = createServicePolicy({ maxRetries, onDegraded });
+              const onDegradedListener = jest.fn();
+              const policy = createServicePolicy({ maxRetries });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -2034,7 +2055,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
 
@@ -2051,12 +2072,12 @@ describe('createServicePolicy', () => {
                 }
                 throw error;
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
-                onDegraded,
                 degradedThreshold,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -2065,7 +2086,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -2083,12 +2104,12 @@ describe('createServicePolicy', () => {
                   }
                 });
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
-                onDegraded,
                 degradedThreshold,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -2097,7 +2118,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
         });
@@ -2140,8 +2161,9 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onBreak = jest.fn();
-            const policy = createServicePolicy({ maxRetries, onBreak });
+            const onBreakListener = jest.fn();
+            const policy = createServicePolicy({ maxRetries });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -2150,8 +2172,8 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await ignoreRejection(promise);
 
-            expect(onBreak).toHaveBeenCalledTimes(1);
-            expect(onBreak).toHaveBeenCalledWith({ error });
+            expect(onBreakListener).toHaveBeenCalledTimes(1);
+            expect(onBreakListener).toHaveBeenCalledWith({ error });
           });
 
           it('does not call the onDegraded callback', async () => {
@@ -2165,8 +2187,9 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onDegraded = jest.fn();
-            const policy = createServicePolicy({ maxRetries, onDegraded });
+            const onDegradedListener = jest.fn();
+            const policy = createServicePolicy({ maxRetries });
+            policy.onDegraded(onDegradedListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -2175,7 +2198,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await ignoreRejection(promise);
 
-            expect(onDegraded).not.toHaveBeenCalled();
+            expect(onDegradedListener).not.toHaveBeenCalled();
           });
 
           describe(`using the default circuit break duration (${DEFAULT_CIRCUIT_BREAK_DURATION})`, () => {
@@ -2257,12 +2280,12 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onBreak = jest.fn();
+            const onBreakListener = jest.fn();
             const policy = createServicePolicy({
               maxRetries,
               maxConsecutiveFailures,
-              onBreak,
             });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -2285,12 +2308,12 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onBreak = jest.fn();
+            const onBreakListener = jest.fn();
             const policy = createServicePolicy({
               maxRetries,
               maxConsecutiveFailures,
-              onBreak,
             });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -2299,7 +2322,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await promise;
 
-            expect(onBreak).not.toHaveBeenCalled();
+            expect(onBreakListener).not.toHaveBeenCalled();
           });
 
           describe(`using the default degraded threshold (${DEFAULT_DEGRADED_THRESHOLD})`, () => {
@@ -2315,12 +2338,12 @@ describe('createServicePolicy', () => {
                 }
                 throw error;
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -2329,7 +2352,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -2347,12 +2370,12 @@ describe('createServicePolicy', () => {
                   }
                 });
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -2361,7 +2384,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
 
@@ -2379,13 +2402,13 @@ describe('createServicePolicy', () => {
                 }
                 throw error;
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onDegraded,
                 degradedThreshold,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -2394,7 +2417,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -2413,13 +2436,13 @@ describe('createServicePolicy', () => {
                   }
                 });
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onDegraded,
                 degradedThreshold,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -2428,7 +2451,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
         });
@@ -2472,12 +2495,12 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onBreak = jest.fn();
+            const onBreakListener = jest.fn();
             const policy = createServicePolicy({
               maxRetries,
               maxConsecutiveFailures,
-              onBreak,
             });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -2486,7 +2509,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await promise;
 
-            expect(onBreak).not.toHaveBeenCalled();
+            expect(onBreakListener).not.toHaveBeenCalled();
           });
 
           describe(`using the default degraded threshold (${DEFAULT_DEGRADED_THRESHOLD})`, () => {
@@ -2502,12 +2525,12 @@ describe('createServicePolicy', () => {
                 }
                 throw error;
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -2516,7 +2539,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -2534,12 +2557,12 @@ describe('createServicePolicy', () => {
                   }
                 });
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onDegraded,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -2548,7 +2571,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
 
@@ -2566,13 +2589,13 @@ describe('createServicePolicy', () => {
                 }
                 throw error;
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onDegraded,
                 degradedThreshold,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -2581,7 +2604,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).not.toHaveBeenCalled();
+              expect(onDegradedListener).not.toHaveBeenCalled();
             });
 
             it('calls the onDegraded callback once if the service execution time is beyond the threshold', async () => {
@@ -2600,13 +2623,13 @@ describe('createServicePolicy', () => {
                   }
                 });
               };
-              const onDegraded = jest.fn();
+              const onDegradedListener = jest.fn();
               const policy = createServicePolicy({
                 maxRetries,
                 maxConsecutiveFailures,
-                onDegraded,
                 degradedThreshold,
               });
+              policy.onDegraded(onDegradedListener);
 
               const promise = policy.execute(mockService);
               // It's safe not to await this promise; adding it to the promise
@@ -2615,7 +2638,7 @@ describe('createServicePolicy', () => {
               clock.runAllAsync();
               await promise;
 
-              expect(onDegraded).toHaveBeenCalledTimes(1);
+              expect(onDegradedListener).toHaveBeenCalledTimes(1);
             });
           });
         });
@@ -2664,12 +2687,12 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onBreak = jest.fn();
+            const onBreakListener = jest.fn();
             const policy = createServicePolicy({
               maxRetries,
               maxConsecutiveFailures,
-              onBreak,
             });
+            policy.onBreak(onBreakListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -2678,8 +2701,8 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await ignoreRejection(promise);
 
-            expect(onBreak).toHaveBeenCalledTimes(1);
-            expect(onBreak).toHaveBeenCalledWith({ error });
+            expect(onBreakListener).toHaveBeenCalledTimes(1);
+            expect(onBreakListener).toHaveBeenCalledWith({ error });
           });
 
           it('does not call the onDegraded callback', async () => {
@@ -2694,12 +2717,12 @@ describe('createServicePolicy', () => {
               }
               throw error;
             };
-            const onDegraded = jest.fn();
+            const onDegradedListener = jest.fn();
             const policy = createServicePolicy({
               maxRetries,
               maxConsecutiveFailures,
-              onDegraded,
             });
+            policy.onDegraded(onDegradedListener);
 
             const promise = policy.execute(mockService);
             // It's safe not to await this promise; adding it to the promise
@@ -2708,7 +2731,7 @@ describe('createServicePolicy', () => {
             clock.runAllAsync();
             await ignoreRejection(promise);
 
-            expect(onDegraded).not.toHaveBeenCalled();
+            expect(onDegradedListener).not.toHaveBeenCalled();
           });
 
           describe(`using the default circuit break duration (${DEFAULT_CIRCUIT_BREAK_DURATION})`, () => {
diff --git a/packages/controller-utils/src/create-service-policy.ts b/packages/controller-utils/src/create-service-policy.ts
index f60ed0f9cb8..971fae8f8cb 100644
--- a/packages/controller-utils/src/create-service-policy.ts
+++ b/packages/controller-utils/src/create-service-policy.ts
@@ -7,9 +7,70 @@ import {
   wrap,
   CircuitState,
 } from 'cockatiel';
-import type { IPolicy, Policy } from 'cockatiel';
+import type {
+  CircuitBreakerPolicy,
+  IPolicy,
+  Policy,
+  RetryPolicy,
+} from 'cockatiel';
 
-export type { IPolicy as IServicePolicy };
+/**
+ * The options for `createServicePolicy`.
+ */
+export type CreateServicePolicyOptions = {
+  /**
+   * The length of time (in milliseconds) to pause retries of the action after
+   * the number of failures reaches `maxConsecutiveFailures`.
+   */
+  circuitBreakDuration?: number;
+  /**
+   * The length of time (in milliseconds) that governs when the service is
+   * regarded as degraded (affecting when `onDegraded` is called).
+   */
+  degradedThreshold?: number;
+  /**
+   * The maximum number of times that the service is allowed to fail before
+   * pausing further retries.
+   */
+  maxConsecutiveFailures?: number;
+  /**
+   * The maximum number of times that a failing service should be re-invoked
+   * before giving up.
+   */
+  maxRetries?: number;
+  /**
+   * The policy used to control when the service should be retried based on
+   * either the result of the service or an error that it throws. For instance,
+   * you could use this to retry only certain errors. See `handleWhen` and
+   * friends from Cockatiel for more.
+   */
+  retryFilterPolicy?: Policy;
+};
+
+/**
+ * The service policy object.
+ */
+export type ServicePolicy = IPolicy & {
+  /**
+   * A function which is called when the number of times that the service fails
+   * in a row meets the set maximum number of consecutive failures.
+   */
+  onBreak: CircuitBreakerPolicy['onBreak'];
+  /**
+   * A function which is called in two circumstances: 1) when the service
+   * succeeds before the maximum number of consecutive failures is reached, but
+   * takes more time than the `degradedThreshold` to run, or 2) if the service
+   * never succeeds before the retry policy gives up and before the maximum
+   * number of consecutive failures has been reached.
+   */
+  onDegraded: (fn: () => void) => void;
+  /**
+   * A function which will be called by the retry policy each time the service
+   * fails and the policy kicks off a timer to re-run the service. This is
+   * primarily useful in tests where we are mocking timers.
+   */
+  onRetry: RetryPolicy['onRetry'];
+};
 
 /**
  * The maximum number of times that a failing service should be re-run before
@@ -19,7 +80,9 @@ export const DEFAULT_MAX_RETRIES = 3;
 
 /**
  * The maximum number of times that the service is allowed to fail before
- * pausing further retries.
+ * pausing further retries. This is set to a value such that if given a
+ * service that continually fails, the policy needs to be executed 3 times
+ * before further retries are paused.
  */
 export const DEFAULT_MAX_CONSECUTIVE_FAILURES = (1 + DEFAULT_MAX_RETRIES) * 3;
 
@@ -65,14 +128,6 @@ export const DEFAULT_DEGRADED_THRESHOLD = 5_000;
  * @param options.degradedThreshold - The length of time (in milliseconds) that
  * governs when the service is regarded as degraded (affecting when `onDegraded`
  * is called). Defaults to 5 seconds.
- * @param options.onBreak - A function which is called when the service fails
- * too many times in a row (specifically, more than `maxConsecutiveFailures`).
- * @param options.onDegraded - A function which is called when the service
- * succeeds before `maxConsecutiveFailures` is reached, but takes more time than
- * the `degradedThreshold` to run.
- * @param options.onRetry - A function which will be called the moment the
- * policy kicks off a timer to re-run the function passed to the policy. This is
- * primarily useful in tests where we are mocking timers.
  * @returns The service policy.
  * @example
  * This function is designed to be used in the context of a service class like
@@ -112,25 +167,7 @@ export function createServicePolicy({
   maxConsecutiveFailures = DEFAULT_MAX_CONSECUTIVE_FAILURES,
   circuitBreakDuration = DEFAULT_CIRCUIT_BREAK_DURATION,
   degradedThreshold = DEFAULT_DEGRADED_THRESHOLD,
-  onBreak = () => {
-    // do nothing
-  },
-  onDegraded = () => {
-    // do nothing
-  },
-  onRetry = () => {
-    // do nothing
-  },
-}: {
-  maxRetries?: number;
-  retryFilterPolicy?: Policy;
-  maxConsecutiveFailures?: number;
-  circuitBreakDuration?: number;
-  degradedThreshold?: number;
-  onBreak?: () => void;
-  onDegraded?: () => void;
-  onRetry?: () => void;
-} = {}): IPolicy {
+}: CreateServicePolicyOptions = {}): ServicePolicy {
   const retryPolicy = retry(retryFilterPolicy, {
     // Note that although the option here is called "max attempts", it's really
     // maximum number of *retries* (attempts past the initial attempt).
@@ -139,6 +176,7 @@ export function createServicePolicy({
     // determined by a backoff formula.
     backoff: new ExponentialBackoff(),
   });
+  const onRetry = retryPolicy.onRetry.bind(retryPolicy);
 
   const circuitBreakerPolicy = circuitBreaker(handleAll, {
     // While the circuit is open, any additional invocations of the service
@@ -150,27 +188,14 @@ export function createServicePolicy({
     halfOpenAfter: circuitBreakDuration,
     breaker: new ConsecutiveBreaker(maxConsecutiveFailures),
   });
+  const onBreak = circuitBreakerPolicy.onBreak.bind(circuitBreakerPolicy);
 
-  // The `onBreak` callback will be called if the service consistently throws
-  // for as many times as exceeds the maximum consecutive number of failures.
-  // Combined with the retry policy, this can happen if:
-  // - `maxConsecutiveFailures` < the default max retries (3) and the policy is
-  // executed once
-  // - `maxConsecutiveFailures` >= the default max retries (3) but the policy is
-  //   executed multiple times, enough for the total number of retries to exceed
-  //   `maxConsecutiveFailures`
-  circuitBreakerPolicy.onBreak(onBreak);
-
-  // The `onRetryPolicy` callback will be called each time the service is
-  // invoked (including retries).
-  retryPolicy.onRetry(onRetry);
-
+  const onDegradedListeners: (() => void)[] = [];
   retryPolicy.onGiveUp(() => {
     if (circuitBreakerPolicy.state === CircuitState.Closed) {
-      // The `onDegraded` callback will be called if the number of retries is
-      // exceeded and the maximum number of consecutive failures has not been
-      // reached yet (whether the policy is called once or multiple times).
-      onDegraded();
+      for (const listener of onDegradedListeners) {
+        listener();
+      }
     }
   });
   retryPolicy.onSuccess(({ duration }) => {
@@ -178,14 +203,23 @@ export function createServicePolicy({
       circuitBreakerPolicy.state === CircuitState.Closed &&
       duration > degradedThreshold
     ) {
-      // The `onDegraded` callback will also be called if the service does not
-      // throw, but the time it takes for the service to run exceeds the
-      // `degradedThreshold`.
-      onDegraded();
+      for (const listener of onDegradedListeners) {
+        listener();
+      }
     }
   });
+  const onDegraded = (listener: () => void) => {
+    onDegradedListeners.push(listener);
+  };
+
+  // Every time the retry policy makes an attempt, it executes the circuit
+  // breaker policy, which executes the service.
+  const policy = wrap(retryPolicy, circuitBreakerPolicy);
 
-  // The retry policy really retries the circuit breaker policy, which invokes
-  // the service.
-  return wrap(retryPolicy, circuitBreakerPolicy);
+  return {
+    ...policy,
+    onBreak,
+    onDegraded,
+    onRetry,
+  };
 }
diff --git a/packages/controller-utils/src/index.ts b/packages/controller-utils/src/index.ts
index 446b9ce3823..67742049deb 100644
--- a/packages/controller-utils/src/index.ts
+++ b/packages/controller-utils/src/index.ts
@@ -5,7 +5,10 @@ export {
   DEFAULT_MAX_RETRIES,
   createServicePolicy,
 } from './create-service-policy';
-export type { IServicePolicy } from './create-service-policy';
+export type {
+  CreateServicePolicyOptions,
+  ServicePolicy,
+} from './create-service-policy';
 export * from './constants';
 export type { NonEmptyArray } from './util';
 export {

From 2e29f94b58dbfbc63227387a6b45642829c0dcbb Mon Sep 17 00:00:00 2001
From: Elliot Winkler <elliot.winkler@gmail.com>
Date: Tue, 7 Jan 2025 13:38:08 -0700
Subject: [PATCH 2/3] Refactor services to align with eventual RpcService

In a future commit, we are adding an RpcService class to
`network-controller` to handle automatic failovers. This class is
different from the existing service classes in a couple of ways:

- RpcService will make use of a new `createServicePolicy` function which
  encapsulates retry and circuit breaker logic. This will relieve the
  consuming module for RpcService from needing to test this logic.
- RpcService will have `onBreak` and `onDegraded` methods instead of
  taking `onBreak` and `onDegraded` callbacks as constructor options.
  This is reflected not only in the class but also in the abstract RPC
  service interface.

To these ends, this commit makes the following changes to
`CodefiTokenPricesServiceV2` in `assets-controllers` and
`ClientConfigApiService` in `remote-feature-flag-controller`:

- Refactor service class to use `createServicePolicy`
- Update the abstract service class interface to extend `ServicePolicy`
  from `controller-utils`, and prepend `I` to the type to indicate that
  it's not a superclass, but an interface
- Deprecate the `onBreak` and `onDegraded` constructor options, and add
  methods instead
---
 eslint-warning-thresholds.json                |    2 +-
 packages/assets-controllers/CHANGELOG.md      |   11 +
 packages/assets-controllers/package.json      |    1 -
 .../src/TokenRatesController.test.ts          |   22 +-
 .../src/TokenRatesController.ts               |    8 +-
 .../assets-controllers/src/assetsUtil.test.ts |    4 +-
 packages/assets-controllers/src/assetsUtil.ts |    6 +-
 .../abstract-token-prices-service.ts          |    5 +-
 .../token-prices-service/codefi-v2.test.ts    | 1164 ++++-------------
 .../src/token-prices-service/codefi-v2.ts     |  151 ++-
 .../src/token-prices-service/index.ts         |    2 +-
 .../CHANGELOG.md                              |   11 +
 .../package.json                              |    3 +-
 .../abstract-client-config-api-service.ts     |   19 +-
 .../client-config-api-service.test.ts         |  157 +--
 .../client-config-api-service.ts              |  163 ++-
 .../remote-feature-flag-controller.test.ts    |    8 +-
 .../src/remote-feature-flag-controller.ts     |   10 +-
 yarn.lock                                     |    2 -
 19 files changed, 564 insertions(+), 1185 deletions(-)

diff --git a/eslint-warning-thresholds.json b/eslint-warning-thresholds.json
index a55d4f88d87..baae7815cfd 100644
--- a/eslint-warning-thresholds.json
+++ b/eslint-warning-thresholds.json
@@ -5,7 +5,7 @@
   "@typescript-eslint/no-unsafe-enum-comparison": 34,
   "@typescript-eslint/no-unused-vars": 41,
   "@typescript-eslint/prefer-promise-reject-errors": 33,
-  "@typescript-eslint/prefer-readonly": 147,
+  "@typescript-eslint/prefer-readonly": 143,
   "import-x/namespace": 189,
   "import-x/no-named-as-default": 1,
   "import-x/no-named-as-default-member": 8,
diff --git a/packages/assets-controllers/CHANGELOG.md b/packages/assets-controllers/CHANGELOG.md
index 4a62573da5b..ada9f939fa5 100644
--- a/packages/assets-controllers/CHANGELOG.md
+++ b/packages/assets-controllers/CHANGELOG.md
@@ -7,6 +7,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add `onBreak` and `onDegraded` methods to `CodefiTokenPricesServiceV2` ([#5109](https://github.com/MetaMask/core/pull/5109))
+  - These serve the same purpose as the `onBreak` and `onDegraded` constructor options, but align more closely with the Cockatiel policy API.
+
+### Changed
+
+- Deprecate `ClientConfigApiService` constructor options `onBreak` and `onDegraded` in favor of methods ([#5109](https://github.com/MetaMask/core/pull/5109))
+- Add `@metamask/controller-utils@^11.4.5` as a dependency ([#5109](https://github.com/MetaMask/core/pull/5109))
+  - `cockatiel` should still be in the dependency tree because it's now a dependency of `@metamask/controller-utils`
+
 ## [46.0.1]
 
 ### Changed
diff --git a/packages/assets-controllers/package.json b/packages/assets-controllers/package.json
index acde5f8d16a..0a70808053a 100644
--- a/packages/assets-controllers/package.json
+++ b/packages/assets-controllers/package.json
@@ -68,7 +68,6 @@
     "async-mutex": "^0.5.0",
     "bitcoin-address-validation": "^2.2.3",
     "bn.js": "^5.2.1",
-    "cockatiel": "^3.1.2",
     "immer": "^9.0.6",
     "lodash": "^4.17.21",
     "multiformats": "^13.1.0",
diff --git a/packages/assets-controllers/src/TokenRatesController.test.ts b/packages/assets-controllers/src/TokenRatesController.test.ts
index db41deddd41..05378c15a80 100644
--- a/packages/assets-controllers/src/TokenRatesController.test.ts
+++ b/packages/assets-controllers/src/TokenRatesController.test.ts
@@ -30,7 +30,7 @@ import {
 } from '../../network-controller/tests/helpers';
 import { TOKEN_PRICES_BATCH_SIZE } from './assetsUtil';
 import type {
-  AbstractTokenPricesService,
+  IAbstractTokenPricesService,
   TokenPrice,
   TokenPricesByTokenAddress,
 } from './token-prices-service/abstract-token-prices-service';
@@ -2093,11 +2093,9 @@ describe('TokenRatesController', () => {
               price: 0.002,
             },
           }),
-          validateCurrencySupported: jest.fn().mockReturnValue(
-            false,
-            // Cast used because this method has an assertion in the return
-            // value that I don't know how to type properly with Jest's mock.
-          ) as unknown as AbstractTokenPricesService['validateCurrencySupported'],
+          validateCurrencySupported(_currency: unknown): _currency is string {
+            return false;
+          },
         });
         nock('https://min-api.cryptocompare.com')
           .get('/data/price')
@@ -2288,11 +2286,9 @@ describe('TokenRatesController', () => {
               value: 0.002,
             },
           }),
-          validateChainIdSupported: jest.fn().mockReturnValue(
-            false,
-            // Cast used because this method has an assertion in the return
-            // value that I don't know how to type properly with Jest's mock.
-          ) as unknown as AbstractTokenPricesService['validateChainIdSupported'],
+          validateChainIdSupported(_chainId: unknown): _chainId is Hex {
+            return false;
+          },
         });
         await withController(
           {
@@ -2758,8 +2754,8 @@ async function callUpdateExchangeRatesMethod({
  * @returns The built mock token prices service.
  */
 function buildMockTokenPricesService(
-  overrides: Partial<AbstractTokenPricesService> = {},
-): AbstractTokenPricesService {
+  overrides: Partial<IAbstractTokenPricesService> = {},
+): IAbstractTokenPricesService {
   return {
     async fetchTokenPrices() {
       return {};
diff --git a/packages/assets-controllers/src/TokenRatesController.ts b/packages/assets-controllers/src/TokenRatesController.ts
index f25702bbf82..5bca2809ea0 100644
--- a/packages/assets-controllers/src/TokenRatesController.ts
+++ b/packages/assets-controllers/src/TokenRatesController.ts
@@ -26,7 +26,7 @@ import { isEqual } from 'lodash';
 
 import { reduceInBatchesSerially, TOKEN_PRICES_BATCH_SIZE } from './assetsUtil';
 import { fetchExchangeRate as fetchNativeCurrencyExchangeRate } from './crypto-compare-service';
-import type { AbstractTokenPricesService } from './token-prices-service/abstract-token-prices-service';
+import type { IAbstractTokenPricesService } from './token-prices-service/abstract-token-prices-service';
 import { getNativeTokenAddress } from './token-prices-service/codefi-v2';
 import type {
   TokensControllerGetStateAction,
@@ -238,7 +238,7 @@ export class TokenRatesController extends StaticIntervalPollingController<TokenR
 
   #pollState = PollState.Inactive;
 
-  #tokenPricesService: AbstractTokenPricesService;
+  readonly #tokenPricesService: IAbstractTokenPricesService;
 
   #inProcessExchangeRateUpdates: Record<`${Hex}:${string}`, Promise<void>> = {};
 
@@ -275,7 +275,7 @@ export class TokenRatesController extends StaticIntervalPollingController<TokenR
   }: {
     interval?: number;
     disabled?: boolean;
-    tokenPricesService: AbstractTokenPricesService;
+    tokenPricesService: IAbstractTokenPricesService;
     messenger: TokenRatesControllerMessenger;
     state?: Partial<TokenRatesControllerState>;
   }) {
@@ -687,7 +687,7 @@ export class TokenRatesController extends StaticIntervalPollingController<TokenR
     let contractNativeInformations;
     const tokenPricesByTokenAddress = await reduceInBatchesSerially<
       Hex,
-      Awaited<ReturnType<AbstractTokenPricesService['fetchTokenPrices']>>
+      Awaited<ReturnType<IAbstractTokenPricesService['fetchTokenPrices']>>
     >({
       values: [...tokenAddresses].sort(),
       batchSize: TOKEN_PRICES_BATCH_SIZE,
diff --git a/packages/assets-controllers/src/assetsUtil.test.ts b/packages/assets-controllers/src/assetsUtil.test.ts
index 17dc36ebf93..a40eccfa542 100644
--- a/packages/assets-controllers/src/assetsUtil.test.ts
+++ b/packages/assets-controllers/src/assetsUtil.test.ts
@@ -10,7 +10,7 @@ import { add0x, type Hex } from '@metamask/utils';
 import * as assetsUtil from './assetsUtil';
 import { TOKEN_PRICES_BATCH_SIZE } from './assetsUtil';
 import type { Nft, NftMetadata } from './NftController';
-import type { AbstractTokenPricesService } from './token-prices-service';
+import type { IAbstractTokenPricesService } from './token-prices-service';
 
 const DEFAULT_IPFS_URL_FORMAT = 'ipfs://';
 const ALTERNATIVE_IPFS_URL_FORMAT = 'ipfs://ipfs/';
@@ -772,7 +772,7 @@ function buildAddress(number: number) {
  *
  * @returns The mocked functions of token prices service.
  */
-function createMockPriceService(): AbstractTokenPricesService {
+function createMockPriceService(): IAbstractTokenPricesService {
   return {
     validateChainIdSupported(_chainId: unknown): _chainId is Hex {
       return true;
diff --git a/packages/assets-controllers/src/assetsUtil.ts b/packages/assets-controllers/src/assetsUtil.ts
index 48b0bcde927..52c0965246d 100644
--- a/packages/assets-controllers/src/assetsUtil.ts
+++ b/packages/assets-controllers/src/assetsUtil.ts
@@ -8,7 +8,7 @@ import { remove0x } from '@metamask/utils';
 import BN from 'bn.js';
 
 import type { Nft, NftMetadata } from './NftController';
-import type { AbstractTokenPricesService } from './token-prices-service';
+import type { IAbstractTokenPricesService } from './token-prices-service';
 import { type ContractExchangeRates } from './TokenRatesController';
 
 /**
@@ -387,7 +387,7 @@ export async function fetchTokenContractExchangeRates({
   tokenAddresses,
   chainId,
 }: {
-  tokenPricesService: AbstractTokenPricesService;
+  tokenPricesService: IAbstractTokenPricesService;
   nativeCurrency: string;
   tokenAddresses: Hex[];
   chainId: Hex;
@@ -403,7 +403,7 @@ export async function fetchTokenContractExchangeRates({
 
   const tokenPricesByTokenAddress = await reduceInBatchesSerially<
     Hex,
-    Awaited<ReturnType<AbstractTokenPricesService['fetchTokenPrices']>>
+    Awaited<ReturnType<IAbstractTokenPricesService['fetchTokenPrices']>>
   >({
     values: [...tokenAddresses].sort(),
     batchSize: TOKEN_PRICES_BATCH_SIZE,
diff --git a/packages/assets-controllers/src/token-prices-service/abstract-token-prices-service.ts b/packages/assets-controllers/src/token-prices-service/abstract-token-prices-service.ts
index a3cd09a0586..bac95f74fec 100644
--- a/packages/assets-controllers/src/token-prices-service/abstract-token-prices-service.ts
+++ b/packages/assets-controllers/src/token-prices-service/abstract-token-prices-service.ts
@@ -1,3 +1,4 @@
+import type { ServicePolicy } from '@metamask/controller-utils';
 import type { Hex } from '@metamask/utils';
 
 /**
@@ -49,11 +50,11 @@ export type TokenPricesByTokenAddress<
  * @template Currency - A type union of valid arguments for the `currency`
  * argument to `fetchTokenPrices`.
  */
-export type AbstractTokenPricesService<
+export type IAbstractTokenPricesService<
   ChainId extends Hex = Hex,
   TokenAddress extends Hex = Hex,
   Currency extends string = string,
-> = {
+> = Partial<Pick<ServicePolicy, 'onBreak' | 'onDegraded'>> & {
   /**
    * Retrieves prices in the given currency for the tokens identified by the
    * given addresses which are expected to live on the given chain.
diff --git a/packages/assets-controllers/src/token-prices-service/codefi-v2.test.ts b/packages/assets-controllers/src/token-prices-service/codefi-v2.test.ts
index e1efe858ec2..8f644e7e02e 100644
--- a/packages/assets-controllers/src/token-prices-service/codefi-v2.test.ts
+++ b/packages/assets-controllers/src/token-prices-service/codefi-v2.test.ts
@@ -14,6 +14,232 @@ import {
 const defaultMaxRetryDelay = 30_000;
 
 describe('CodefiTokenPricesServiceV2', () => {
+  describe('onBreak', () => {
+    let clock: sinon.SinonFakeTimers;
+
+    beforeEach(() => {
+      clock = useFakeTimers({ now: Date.now() });
+    });
+
+    afterEach(() => {
+      clock.restore();
+    });
+
+    it('registers a listener that is called upon break', async () => {
+      const retries = 3;
+      // Max consencutive failures is set to match number of calls in three update attempts (including retries)
+      const maximumConsecutiveFailures = (1 + retries) * 3;
+      // Initial interceptor for failing requests
+      nock('https://price.api.cx.metamask.io')
+        .get('/v2/chains/1/spot-prices')
+        .query({
+          tokenAddresses:
+            '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
+          vsCurrency: 'ETH',
+          includeMarketData: 'true',
+        })
+        .times(maximumConsecutiveFailures)
+        .replyWithError('Failed to fetch');
+      // This interceptor should not be used
+      nock('https://price.api.cx.metamask.io')
+        .get('/v2/chains/1/spot-prices')
+        .query({
+          tokenAddresses:
+            '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
+          vsCurrency: 'ETH',
+          includeMarketData: 'true',
+        })
+        .reply(200, {
+          '0x0000000000000000000000000000000000000000': {
+            price: 14,
+            currency: 'ETH',
+            pricePercentChange1d: 1,
+            priceChange1d: 1,
+            marketCap: 117219.99428314982,
+            allTimeHigh: 0.00060467892389492,
+            allTimeLow: 0.00002303954000865728,
+            totalVolume: 5155.094053542448,
+            high1d: 0.00008020715848194385,
+            low1d: 0.00007792083564549064,
+            circulatingSupply: 1494269733.9526057,
+            dilutedMarketCap: 117669.5125951733,
+            marketCapPercentChange1d: 0.76671,
+            pricePercentChange1h: -1.0736342953259423,
+            pricePercentChange7d: -7.351582573655089,
+            pricePercentChange14d: -1.0799098946709822,
+            pricePercentChange30d: -25.776321124365992,
+            pricePercentChange200d: 46.091571238599165,
+            pricePercentChange1y: -2.2992517267242754,
+          },
+          '0xaaa': {
+            price: 148.17205755299946,
+            currency: 'ETH',
+            pricePercentChange1d: 1,
+            priceChange1d: 1,
+            marketCap: 117219.99428314982,
+            allTimeHigh: 0.00060467892389492,
+            allTimeLow: 0.00002303954000865728,
+            totalVolume: 5155.094053542448,
+            high1d: 0.00008020715848194385,
+            low1d: 0.00007792083564549064,
+            circulatingSupply: 1494269733.9526057,
+            dilutedMarketCap: 117669.5125951733,
+            marketCapPercentChange1d: 0.76671,
+            pricePercentChange1h: -1.0736342953259423,
+            pricePercentChange7d: -7.351582573655089,
+            pricePercentChange14d: -1.0799098946709822,
+            pricePercentChange30d: -25.776321124365992,
+            pricePercentChange200d: 46.091571238599165,
+            pricePercentChange1y: -2.2992517267242754,
+          },
+          '0xbbb': {
+            price: 33689.98134554716,
+            currency: 'ETH',
+            pricePercentChange1d: 1,
+            priceChange1d: 1,
+            marketCap: 117219.99428314982,
+            allTimeHigh: 0.00060467892389492,
+            allTimeLow: 0.00002303954000865728,
+            totalVolume: 5155.094053542448,
+            high1d: 0.00008020715848194385,
+            low1d: 0.00007792083564549064,
+            circulatingSupply: 1494269733.9526057,
+            dilutedMarketCap: 117669.5125951733,
+            marketCapPercentChange1d: 0.76671,
+            pricePercentChange1h: -1.0736342953259423,
+            pricePercentChange7d: -7.351582573655089,
+            pricePercentChange14d: -1.0799098946709822,
+            pricePercentChange30d: -25.776321124365992,
+            pricePercentChange200d: 46.091571238599165,
+            pricePercentChange1y: -2.2992517267242754,
+          },
+          '0xccc': {
+            price: 148.1344197578456,
+            currency: 'ETH',
+            pricePercentChange1d: 1,
+            priceChange1d: 1,
+            marketCap: 117219.99428314982,
+            allTimeHigh: 0.00060467892389492,
+            allTimeLow: 0.00002303954000865728,
+            totalVolume: 5155.094053542448,
+            high1d: 0.00008020715848194385,
+            low1d: 0.00007792083564549064,
+            circulatingSupply: 1494269733.9526057,
+            dilutedMarketCap: 117669.5125951733,
+            marketCapPercentChange1d: 0.76671,
+            pricePercentChange1h: -1.0736342953259423,
+            pricePercentChange7d: -7.351582573655089,
+            pricePercentChange14d: -1.0799098946709822,
+            pricePercentChange30d: -25.776321124365992,
+            pricePercentChange200d: 46.091571238599165,
+            pricePercentChange1y: -2.2992517267242754,
+          },
+        });
+      const onBreakHandler = jest.fn();
+      const service = new CodefiTokenPricesServiceV2({
+        retries,
+        maximumConsecutiveFailures,
+        // Ensure break duration is well over the max delay for a single request, so that the
+        // break doesn't end during a retry attempt
+        circuitBreakDuration: defaultMaxRetryDelay * 10,
+      });
+      service.onBreak(onBreakHandler);
+      const fetchTokenPrices = () =>
+        service.fetchTokenPrices({
+          chainId: '0x1',
+          tokenAddresses: ['0xAAA', '0xBBB', '0xCCC'],
+          currency: 'ETH',
+        });
+      expect(onBreakHandler).not.toHaveBeenCalled();
+
+      // Initial three calls to exhaust maximum allowed failures
+      // eslint-disable-next-line @typescript-eslint/no-unused-vars
+      for (const _retryAttempt of Array(retries).keys()) {
+        // eslint-disable-next-line no-loop-func
+        await expect(() =>
+          fetchTokenPricesWithFakeTimers({
+            clock,
+            fetchTokenPrices,
+            retries,
+          }),
+        ).rejects.toThrow('Failed to fetch');
+      }
+
+      expect(onBreakHandler).toHaveBeenCalledTimes(1);
+    });
+  });
+
+  describe('onDegraded', () => {
+    let clock: sinon.SinonFakeTimers;
+
+    beforeEach(() => {
+      clock = useFakeTimers({ now: Date.now() });
+    });
+
+    afterEach(() => {
+      clock.restore();
+    });
+
+    it('calls onDegraded when request is slower than threshold', async () => {
+      const degradedThreshold = 1000;
+      const retries = 0;
+      nock('https://price.api.cx.metamask.io')
+        .get('/v2/chains/1/spot-prices')
+        .query({
+          tokenAddresses:
+            '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
+          vsCurrency: 'ETH',
+          includeMarketData: 'true',
+        })
+        .delay(degradedThreshold * 2)
+        .reply(200, {
+          '0x0000000000000000000000000000000000000000': {
+            price: 14,
+            currency: 'ETH',
+            pricePercentChange1d: 1,
+            priceChange1d: 1,
+          },
+          '0xaaa': {
+            price: 148.17205755299946,
+            currency: 'ETH',
+            pricePercentChange1d: 1,
+            priceChange1d: 1,
+          },
+          '0xbbb': {
+            price: 33689.98134554716,
+            currency: 'ETH',
+            pricePercentChange1d: 1,
+            priceChange1d: 1,
+          },
+          '0xccc': {
+            price: 148.1344197578456,
+            currency: 'ETH',
+            pricePercentChange1d: 1,
+            priceChange1d: 1,
+          },
+        });
+      const onDegradedHandler = jest.fn();
+      const service = new CodefiTokenPricesServiceV2({
+        degradedThreshold,
+        retries,
+      });
+      service.onDegraded(onDegradedHandler);
+
+      await fetchTokenPricesWithFakeTimers({
+        clock,
+        fetchTokenPrices: () =>
+          service.fetchTokenPrices({
+            chainId: '0x1',
+            tokenAddresses: ['0xAAA', '0xBBB', '0xCCC'],
+            currency: 'ETH',
+          }),
+        retries,
+      });
+
+      expect(onDegradedHandler).toHaveBeenCalledTimes(1);
+    });
+  });
+
   describe('fetchTokenPrices', () => {
     it('uses the /spot-prices endpoint of the Codefi Price API to gather prices for the given tokens', async () => {
       nock('https://price.api.cx.metamask.io')
@@ -829,8 +1055,9 @@ describe('CodefiTokenPricesServiceV2', () => {
         clock.restore();
       });
 
-      it('does not call onDegraded when requests succeeds faster than threshold', async () => {
+      it('calls onDegraded when request is slower than threshold', async () => {
         const degradedThreshold = 1000;
+        const retries = 0;
         nock('https://price.api.cx.metamask.io')
           .get('/v2/chains/1/spot-prices')
           .query({
@@ -839,326 +1066,38 @@ describe('CodefiTokenPricesServiceV2', () => {
             vsCurrency: 'ETH',
             includeMarketData: 'true',
           })
-          .delay(degradedThreshold / 2)
+          .delay(degradedThreshold * 2)
           .reply(200, {
             '0x0000000000000000000000000000000000000000': {
               price: 14,
               currency: 'ETH',
               pricePercentChange1d: 1,
               priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
             },
             '0xaaa': {
               price: 148.17205755299946,
               currency: 'ETH',
               pricePercentChange1d: 1,
               priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
             },
             '0xbbb': {
               price: 33689.98134554716,
               currency: 'ETH',
               pricePercentChange1d: 1,
               priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
             },
             '0xccc': {
               price: 148.1344197578456,
               currency: 'ETH',
               pricePercentChange1d: 1,
               priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
             },
           });
         const onDegradedHandler = jest.fn();
         const service = new CodefiTokenPricesServiceV2({
           degradedThreshold,
           onDegraded: onDegradedHandler,
-        });
-
-        await service.fetchTokenPrices({
-          chainId: '0x1',
-          tokenAddresses: ['0xAAA', '0xBBB', '0xCCC'],
-          currency: 'ETH',
-        });
-
-        expect(onDegradedHandler).not.toHaveBeenCalled();
-      });
-
-      it('does not call onDegraded when requests succeeds on retry faster than threshold', async () => {
-        // Set threshold above max retry delay to ensure the time is always under the threshold,
-        // even with random jitter
-        const degradedThreshold = defaultMaxRetryDelay + 1000;
-        const retries = 1;
-        // Initial interceptor for failing request
-        nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses:
-              '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-            includeMarketData: 'true',
-          })
-          .replyWithError('Failed to fetch');
-        // Second interceptor for successful response
-        nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses:
-              '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-            includeMarketData: 'true',
-          })
-          .delay(500)
-          .reply(200, {
-            '0x0000000000000000000000000000000000000000': {
-              price: 14,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-            },
-            '0xaaa': {
-              price: 148.17205755299946,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-            },
-            '0xbbb': {
-              price: 33689.98134554716,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-            },
-            '0xccc': {
-              price: 148.1344197578456,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-            },
-          });
-        const onDegradedHandler = jest.fn();
-        const service = new CodefiTokenPricesServiceV2({
-          degradedThreshold,
-          onDegraded: onDegradedHandler,
-          retries,
-        });
-
-        await fetchTokenPricesWithFakeTimers({
-          clock,
-          fetchTokenPrices: () =>
-            service.fetchTokenPrices({
-              chainId: '0x1',
-              tokenAddresses: ['0xAAA', '0xBBB', '0xCCC'],
-              currency: 'ETH',
-            }),
-          retries,
-        });
-
-        expect(onDegradedHandler).not.toHaveBeenCalled();
-      });
-
-      it('calls onDegraded when request fails', async () => {
-        const retries = 0;
-        nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses:
-              '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-            includeMarketData: 'true',
-          })
-          .replyWithError('Failed to fetch');
-        const onDegradedHandler = jest.fn();
-        const service = new CodefiTokenPricesServiceV2({
-          onDegraded: onDegradedHandler,
-          retries,
-        });
-
-        await expect(() =>
-          fetchTokenPricesWithFakeTimers({
-            clock,
-            fetchTokenPrices: () =>
-              service.fetchTokenPrices({
-                chainId: '0x1',
-                tokenAddresses: ['0xAAA', '0xBBB', '0xCCC'],
-                currency: 'ETH',
-              }),
-            retries,
-          }),
-        ).rejects.toThrow('Failed to fetch');
-
-        expect(onDegradedHandler).toHaveBeenCalledTimes(1);
-      });
-
-      it('calls onDegraded when request is slower than threshold', async () => {
-        const degradedThreshold = 1000;
-        const retries = 0;
-        nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses:
-              '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-            includeMarketData: 'true',
-          })
-          .delay(degradedThreshold * 2)
-          .reply(200, {
-            '0x0000000000000000000000000000000000000000': {
-              price: 14,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-            },
-            '0xaaa': {
-              price: 148.17205755299946,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-            },
-            '0xbbb': {
-              price: 33689.98134554716,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-            },
-            '0xccc': {
-              price: 148.1344197578456,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-            },
-          });
-        const onDegradedHandler = jest.fn();
-        const service = new CodefiTokenPricesServiceV2({
-          degradedThreshold,
-          onDegraded: onDegradedHandler,
-          retries,
-        });
-
-        await fetchTokenPricesWithFakeTimers({
-          clock,
-          fetchTokenPrices: () =>
-            service.fetchTokenPrices({
-              chainId: '0x1',
-              tokenAddresses: ['0xAAA', '0xBBB', '0xCCC'],
-              currency: 'ETH',
-            }),
-          retries,
-        });
-
-        expect(onDegradedHandler).toHaveBeenCalledTimes(1);
-      });
-
-      it('calls onDegraded when request is slower than threshold after retry', async () => {
-        const degradedThreshold = 1000;
-        const retries = 1;
-        // Initial interceptor for failing request
-        nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses:
-              '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-            includeMarketData: 'true',
-          })
-          .replyWithError('Failed to fetch');
-        // Second interceptor for successful response
-        nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses:
-              '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-            includeMarketData: 'true',
-          })
-          .delay(degradedThreshold * 2)
-          .reply(200, {
-            '0x0000000000000000000000000000000000000000': {
-              price: 14,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-            },
-            '0xaaa': {
-              price: 148.17205755299946,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-            },
-            '0xbbb': {
-              price: 33689.98134554716,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-            },
-            '0xccc': {
-              price: 148.1344197578456,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-            },
-          });
-        const onDegradedHandler = jest.fn();
-        const service = new CodefiTokenPricesServiceV2({
-          degradedThreshold,
-          onDegraded: onDegradedHandler,
-          retries,
+          retries,
         });
 
         await fetchTokenPricesWithFakeTimers({
@@ -1187,7 +1126,7 @@ describe('CodefiTokenPricesServiceV2', () => {
         clock.restore();
       });
 
-      it('stops making fetch requests after too many consecutive failures', async () => {
+      it('calls onBreak handler upon break', async () => {
         const retries = 3;
         // Max consencutive failures is set to match number of calls in three update attempts (including retries)
         const maximumConsecutiveFailures = (1 + retries) * 3;
@@ -1203,7 +1142,7 @@ describe('CodefiTokenPricesServiceV2', () => {
           .times(maximumConsecutiveFailures)
           .replyWithError('Failed to fetch');
         // This interceptor should not be used
-        const successfullCallScope = nock('https://price.api.cx.metamask.io')
+        nock('https://price.api.cx.metamask.io')
           .get('/v2/chains/1/spot-prices')
           .query({
             tokenAddresses:
@@ -1297,9 +1236,11 @@ describe('CodefiTokenPricesServiceV2', () => {
               pricePercentChange1y: -2.2992517267242754,
             },
           });
+        const onBreakHandler = jest.fn();
         const service = new CodefiTokenPricesServiceV2({
           retries,
           maximumConsecutiveFailures,
+          onBreak: onBreakHandler,
           // Ensure break duration is well over the max delay for a single request, so that the
           // break doesn't end during a retry attempt
           circuitBreakDuration: defaultMaxRetryDelay * 10,
@@ -1310,6 +1251,8 @@ describe('CodefiTokenPricesServiceV2', () => {
             tokenAddresses: ['0xAAA', '0xBBB', '0xCCC'],
             currency: 'ETH',
           });
+        expect(onBreakHandler).not.toHaveBeenCalled();
+
         // Initial three calls to exhaust maximum allowed failures
         // eslint-disable-next-line @typescript-eslint/no-unused-vars
         for (const _retryAttempt of Array(retries).keys()) {
@@ -1323,642 +1266,7 @@ describe('CodefiTokenPricesServiceV2', () => {
           ).rejects.toThrow('Failed to fetch');
         }
 
-        await expect(() =>
-          fetchTokenPricesWithFakeTimers({
-            clock,
-            fetchTokenPrices,
-            retries,
-          }),
-        ).rejects.toThrow(
-          'Execution prevented because the circuit breaker is open',
-        );
-        expect(successfullCallScope.isDone()).toBe(false);
-      });
-
-      it('calls onBreak handler upon break', async () => {
-        const retries = 3;
-        // Max consencutive failures is set to match number of calls in three update attempts (including retries)
-        const maximumConsecutiveFailures = (1 + retries) * 3;
-        // Initial interceptor for failing requests
-        nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses:
-              '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-            includeMarketData: 'true',
-          })
-          .times(maximumConsecutiveFailures)
-          .replyWithError('Failed to fetch');
-        // This interceptor should not be used
-        nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses:
-              '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-            includeMarketData: 'true',
-          })
-          .reply(200, {
-            '0x0000000000000000000000000000000000000000': {
-              price: 14,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
-            },
-            '0xaaa': {
-              price: 148.17205755299946,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
-            },
-            '0xbbb': {
-              price: 33689.98134554716,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
-            },
-            '0xccc': {
-              price: 148.1344197578456,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
-            },
-          });
-        const onBreakHandler = jest.fn();
-        const service = new CodefiTokenPricesServiceV2({
-          retries,
-          maximumConsecutiveFailures,
-          // Ensure break duration is well over the max delay for a single request, so that the
-          // break doesn't end during a retry attempt
-          onBreak: onBreakHandler,
-          circuitBreakDuration: defaultMaxRetryDelay * 10,
-        });
-        const fetchTokenPrices = () =>
-          service.fetchTokenPrices({
-            chainId: '0x1',
-            tokenAddresses: ['0xAAA', '0xBBB', '0xCCC'],
-            currency: 'ETH',
-          });
-        expect(onBreakHandler).not.toHaveBeenCalled();
-
-        // Initial three calls to exhaust maximum allowed failures
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        for (const _retryAttempt of Array(retries).keys()) {
-          // eslint-disable-next-line no-loop-func
-          await expect(() =>
-            fetchTokenPricesWithFakeTimers({
-              clock,
-              fetchTokenPrices,
-              retries,
-            }),
-          ).rejects.toThrow('Failed to fetch');
-        }
-
-        expect(onBreakHandler).toHaveBeenCalledTimes(1);
-      });
-
-      it('stops calling onDegraded after circuit break', async () => {
-        const retries = 3;
-        // Max consencutive failures is set to match number of calls in three update attempts (including retries)
-        const maximumConsecutiveFailures = (1 + retries) * 3;
-        // Initial interceptor for failing requests
-        nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses:
-              '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-            includeMarketData: 'true',
-          })
-          .times(maximumConsecutiveFailures)
-          .replyWithError('Failed to fetch');
-        const onBreakHandler = jest.fn();
-        const onDegradedHandler = jest.fn();
-        const service = new CodefiTokenPricesServiceV2({
-          retries,
-          maximumConsecutiveFailures,
-          // Ensure break duration is well over the max delay for a single request, so that the
-          // break doesn't end during a retry attempt
-          onBreak: onBreakHandler,
-          onDegraded: onDegradedHandler,
-          circuitBreakDuration: defaultMaxRetryDelay * 10,
-        });
-        const fetchTokenPrices = () =>
-          service.fetchTokenPrices({
-            chainId: '0x1',
-            tokenAddresses: ['0xAAA', '0xBBB', '0xCCC'],
-            currency: 'ETH',
-          });
-        expect(onBreakHandler).not.toHaveBeenCalled();
-        // Initial three calls to exhaust maximum allowed failures
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        for (const _retryAttempt of Array(retries).keys()) {
-          // eslint-disable-next-line no-loop-func
-          await expect(() =>
-            fetchTokenPricesWithFakeTimers({
-              clock,
-              fetchTokenPrices,
-              retries,
-            }),
-          ).rejects.toThrow('Failed to fetch');
-        }
-        // Confirm that circuit is broken
         expect(onBreakHandler).toHaveBeenCalledTimes(1);
-        // Should be called twice by now, once per update attempt prior to break
-        expect(onDegradedHandler).toHaveBeenCalledTimes(2);
-
-        await expect(() =>
-          fetchTokenPricesWithFakeTimers({
-            clock,
-            fetchTokenPrices,
-            retries,
-          }),
-        ).rejects.toThrow(
-          'Execution prevented because the circuit breaker is open',
-        );
-
-        expect(onDegradedHandler).toHaveBeenCalledTimes(2);
-      });
-
-      it('keeps circuit closed if first request fails when half-open', async () => {
-        const retries = 3;
-        // Max consencutive failures is set to match number of calls in three update attempts (including retries)
-        const maximumConsecutiveFailures = (1 + retries) * 3;
-        // Ensure break duration is well over the max delay for a single request, so that the
-        // break doesn't end during a retry attempt
-        const circuitBreakDuration = defaultMaxRetryDelay * 10;
-        // Initial interceptor for failing requests
-        nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses:
-              '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-            includeMarketData: 'true',
-          })
-          // The +1 is for the additional request when the circuit is half-open
-          .times(maximumConsecutiveFailures + 1)
-          .replyWithError('Failed to fetch');
-        // This interceptor should not be used
-        const successfullCallScope = nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses: '0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-          })
-          .reply(200, {
-            '0x0000000000000000000000000000000000000000': {
-              price: 14,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
-            },
-            '0xaaa': {
-              price: 148.17205755299946,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
-            },
-            '0xbbb': {
-              price: 33689.98134554716,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
-            },
-            '0xccc': {
-              price: 148.1344197578456,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
-            },
-          });
-        const service = new CodefiTokenPricesServiceV2({
-          retries,
-          maximumConsecutiveFailures,
-          circuitBreakDuration,
-        });
-        const fetchTokenPrices = () =>
-          service.fetchTokenPrices({
-            chainId: '0x1',
-            tokenAddresses: ['0xAAA', '0xBBB', '0xCCC'],
-            currency: 'ETH',
-          });
-        // Initial three calls to exhaust maximum allowed failures
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        for (const _retryAttempt of Array(retries).keys()) {
-          // eslint-disable-next-line no-loop-func
-          await expect(() =>
-            fetchTokenPricesWithFakeTimers({
-              clock,
-              fetchTokenPrices,
-              retries,
-            }),
-          ).rejects.toThrow('Failed to fetch');
-        }
-        // Confirm that circuit has broken
-        await expect(() =>
-          fetchTokenPricesWithFakeTimers({
-            clock,
-            fetchTokenPrices,
-            retries,
-          }),
-        ).rejects.toThrow(
-          'Execution prevented because the circuit breaker is open',
-        );
-        // Wait for circuit to move to half-open
-        await clock.tickAsync(circuitBreakDuration);
-
-        // The circuit should remain open after the first request fails
-        // The fetch error is replaced by the circuit break error due to the retries
-        await expect(() =>
-          fetchTokenPricesWithFakeTimers({
-            clock,
-            fetchTokenPrices,
-            retries,
-          }),
-        ).rejects.toThrow(
-          'Execution prevented because the circuit breaker is open',
-        );
-
-        // Confirm that the circuit is still open
-        await expect(() =>
-          fetchTokenPricesWithFakeTimers({
-            clock,
-            fetchTokenPrices,
-            retries,
-          }),
-        ).rejects.toThrow(
-          'Execution prevented because the circuit breaker is open',
-        );
-        expect(successfullCallScope.isDone()).toBe(false);
-      });
-
-      it('recovers after circuit break', async () => {
-        const retries = 3;
-        // Max consencutive failures is set to match number of calls in three update attempts (including retries)
-        const maximumConsecutiveFailures = (1 + retries) * 3;
-        // Ensure break duration is well over the max delay for a single request, so that the
-        // break doesn't end during a retry attempt
-        const circuitBreakDuration = defaultMaxRetryDelay * 10;
-        // Initial interceptor for failing requests
-        nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses:
-              '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-            includeMarketData: 'true',
-          })
-          .times(maximumConsecutiveFailures)
-          .replyWithError('Failed to fetch');
-        // Later interceptor for successfull request after recovery
-        nock('https://price.api.cx.metamask.io')
-          .get('/v2/chains/1/spot-prices')
-          .query({
-            tokenAddresses:
-              '0x0000000000000000000000000000000000000000,0xAAA,0xBBB,0xCCC',
-            vsCurrency: 'ETH',
-            includeMarketData: 'true',
-          })
-          .reply(200, {
-            '0x0000000000000000000000000000000000000000': {
-              price: 14,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
-            },
-            '0xaaa': {
-              price: 148.17205755299946,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
-            },
-            '0xbbb': {
-              price: 33689.98134554716,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
-            },
-            '0xccc': {
-              price: 148.1344197578456,
-              currency: 'ETH',
-              pricePercentChange1d: 1,
-              priceChange1d: 1,
-              marketCap: 117219.99428314982,
-              allTimeHigh: 0.00060467892389492,
-              allTimeLow: 0.00002303954000865728,
-              totalVolume: 5155.094053542448,
-              high1d: 0.00008020715848194385,
-              low1d: 0.00007792083564549064,
-              circulatingSupply: 1494269733.9526057,
-              dilutedMarketCap: 117669.5125951733,
-              marketCapPercentChange1d: 0.76671,
-              pricePercentChange1h: -1.0736342953259423,
-              pricePercentChange7d: -7.351582573655089,
-              pricePercentChange14d: -1.0799098946709822,
-              pricePercentChange30d: -25.776321124365992,
-              pricePercentChange200d: 46.091571238599165,
-              pricePercentChange1y: -2.2992517267242754,
-            },
-          });
-        const service = new CodefiTokenPricesServiceV2({
-          retries,
-          maximumConsecutiveFailures,
-          circuitBreakDuration,
-        });
-        const fetchTokenPrices = () =>
-          service.fetchTokenPrices({
-            chainId: '0x1',
-            tokenAddresses: ['0xAAA', '0xBBB', '0xCCC'],
-            currency: 'ETH',
-          });
-        // Initial three calls to exhaust maximum allowed failures
-        // eslint-disable-next-line @typescript-eslint/no-unused-vars
-        for (const _retryAttempt of Array(retries).keys()) {
-          // eslint-disable-next-line no-loop-func
-          await expect(() =>
-            fetchTokenPricesWithFakeTimers({
-              clock,
-              fetchTokenPrices,
-              retries,
-            }),
-          ).rejects.toThrow('Failed to fetch');
-        }
-        // Confirm that circuit has broken
-        await expect(() =>
-          fetchTokenPricesWithFakeTimers({
-            clock,
-            fetchTokenPrices,
-            retries,
-          }),
-        ).rejects.toThrow(
-          'Execution prevented because the circuit breaker is open',
-        );
-        // Wait for circuit to move to half-open
-        await clock.tickAsync(circuitBreakDuration);
-
-        const marketDataTokensByAddress = await fetchTokenPricesWithFakeTimers({
-          clock,
-          fetchTokenPrices,
-          retries,
-        });
-
-        expect(marketDataTokensByAddress).toStrictEqual({
-          '0x0000000000000000000000000000000000000000': {
-            tokenAddress: '0x0000000000000000000000000000000000000000',
-            currency: 'ETH',
-            pricePercentChange1d: 1,
-            priceChange1d: 1,
-            marketCap: 117219.99428314982,
-            allTimeHigh: 0.00060467892389492,
-            allTimeLow: 0.00002303954000865728,
-            totalVolume: 5155.094053542448,
-            high1d: 0.00008020715848194385,
-            low1d: 0.00007792083564549064,
-            price: 14,
-            circulatingSupply: 1494269733.9526057,
-            dilutedMarketCap: 117669.5125951733,
-            marketCapPercentChange1d: 0.76671,
-            pricePercentChange1h: -1.0736342953259423,
-            pricePercentChange7d: -7.351582573655089,
-            pricePercentChange14d: -1.0799098946709822,
-            pricePercentChange30d: -25.776321124365992,
-            pricePercentChange200d: 46.091571238599165,
-            pricePercentChange1y: -2.2992517267242754,
-          },
-          '0xAAA': {
-            tokenAddress: '0xAAA',
-            currency: 'ETH',
-            pricePercentChange1d: 1,
-            priceChange1d: 1,
-            marketCap: 117219.99428314982,
-            allTimeHigh: 0.00060467892389492,
-            allTimeLow: 0.00002303954000865728,
-            totalVolume: 5155.094053542448,
-            high1d: 0.00008020715848194385,
-            low1d: 0.00007792083564549064,
-            price: 148.17205755299946,
-            circulatingSupply: 1494269733.9526057,
-            dilutedMarketCap: 117669.5125951733,
-            marketCapPercentChange1d: 0.76671,
-            pricePercentChange1h: -1.0736342953259423,
-            pricePercentChange7d: -7.351582573655089,
-            pricePercentChange14d: -1.0799098946709822,
-            pricePercentChange30d: -25.776321124365992,
-            pricePercentChange200d: 46.091571238599165,
-            pricePercentChange1y: -2.2992517267242754,
-          },
-          '0xBBB': {
-            tokenAddress: '0xBBB',
-            currency: 'ETH',
-            pricePercentChange1d: 1,
-            priceChange1d: 1,
-            marketCap: 117219.99428314982,
-            allTimeHigh: 0.00060467892389492,
-            allTimeLow: 0.00002303954000865728,
-            totalVolume: 5155.094053542448,
-            high1d: 0.00008020715848194385,
-            low1d: 0.00007792083564549064,
-            price: 33689.98134554716,
-            circulatingSupply: 1494269733.9526057,
-            dilutedMarketCap: 117669.5125951733,
-            marketCapPercentChange1d: 0.76671,
-            pricePercentChange1h: -1.0736342953259423,
-            pricePercentChange7d: -7.351582573655089,
-            pricePercentChange14d: -1.0799098946709822,
-            pricePercentChange30d: -25.776321124365992,
-            pricePercentChange200d: 46.091571238599165,
-            pricePercentChange1y: -2.2992517267242754,
-          },
-          '0xCCC': {
-            tokenAddress: '0xCCC',
-            currency: 'ETH',
-            pricePercentChange1d: 1,
-            priceChange1d: 1,
-            marketCap: 117219.99428314982,
-            allTimeHigh: 0.00060467892389492,
-            allTimeLow: 0.00002303954000865728,
-            totalVolume: 5155.094053542448,
-            high1d: 0.00008020715848194385,
-            low1d: 0.00007792083564549064,
-            price: 148.1344197578456,
-            circulatingSupply: 1494269733.9526057,
-            dilutedMarketCap: 117669.5125951733,
-            marketCapPercentChange1d: 0.76671,
-            pricePercentChange1h: -1.0736342953259423,
-            pricePercentChange7d: -7.351582573655089,
-            pricePercentChange14d: -1.0799098946709822,
-            pricePercentChange30d: -25.776321124365992,
-            pricePercentChange200d: 46.091571238599165,
-            pricePercentChange1y: -2.2992517267242754,
-          },
-        });
       });
     });
   });
diff --git a/packages/assets-controllers/src/token-prices-service/codefi-v2.ts b/packages/assets-controllers/src/token-prices-service/codefi-v2.ts
index 4f163203e4d..cbc3f05b60f 100644
--- a/packages/assets-controllers/src/token-prices-service/codefi-v2.ts
+++ b/packages/assets-controllers/src/token-prices-service/codefi-v2.ts
@@ -1,19 +1,17 @@
-import { handleFetch } from '@metamask/controller-utils';
+import {
+  createServicePolicy,
+  DEFAULT_CIRCUIT_BREAK_DURATION,
+  DEFAULT_DEGRADED_THRESHOLD,
+  DEFAULT_MAX_CONSECUTIVE_FAILURES,
+  DEFAULT_MAX_RETRIES,
+  handleFetch,
+} from '@metamask/controller-utils';
+import type { ServicePolicy } from '@metamask/controller-utils';
 import type { Hex } from '@metamask/utils';
 import { hexToNumber } from '@metamask/utils';
-import {
-  circuitBreaker,
-  ConsecutiveBreaker,
-  ExponentialBackoff,
-  handleAll,
-  type IPolicy,
-  retry,
-  wrap,
-  CircuitState,
-} from 'cockatiel';
 
 import type {
-  AbstractTokenPricesService,
+  IAbstractTokenPricesService,
   TokenPrice,
   TokenPricesByTokenAddress,
 } from './abstract-token-prices-service';
@@ -271,13 +269,6 @@ type SupportedChainId = (typeof SUPPORTED_CHAIN_IDS)[number];
  */
 const BASE_URL = 'https://price.api.cx.metamask.io/v2';
 
-const DEFAULT_TOKEN_PRICE_RETRIES = 3;
-// Each update attempt will result (1 + retries) calls if the server is down
-const DEFAULT_TOKEN_PRICE_MAX_CONSECUTIVE_FAILURES =
-  (1 + DEFAULT_TOKEN_PRICE_RETRIES) * 3;
-
-const DEFAULT_DEGRADED_THRESHOLD = 5_000;
-
 /**
  * The shape of the data that the /spot-prices endpoint returns.
  */
@@ -363,33 +354,66 @@ type MarketDataByTokenAddress = { [address: Hex]: MarketData };
  */
 export class CodefiTokenPricesServiceV2
   implements
-    AbstractTokenPricesService<SupportedChainId, Hex, SupportedCurrency>
+    IAbstractTokenPricesService<SupportedChainId, Hex, SupportedCurrency>
 {
-  #tokenPricePolicy: IPolicy;
+  readonly #policy: ServicePolicy;
 
   /**
    * Construct a Codefi Token Price Service.
    *
-   * @param options - Constructor options
-   * @param options.degradedThreshold - The threshold between "normal" and "degrated" service,
-   * in milliseconds.
-   * @param options.retries - Number of retry attempts for each token price update.
-   * @param options.maximumConsecutiveFailures - The maximum number of consecutive failures
-   * allowed before breaking the circuit and pausing further updates.
-   * @param options.onBreak - An event handler for when the circuit breaks, useful for capturing
-   * metrics about network failures.
-   * @param options.onDegraded - An event handler for when the circuit remains closed, but requests
-   * are failing or resolving too slowly (i.e. resolving more slowly than the `degradedThreshold).
-   * @param options.circuitBreakDuration - The amount of time to wait when the circuit breaks
-   * from too many consecutive failures.
+   * @param args - The arguments.
+   * @param args.degradedThreshold - The length of time (in milliseconds)
+   * that governs when the service is regarded as degraded (affecting when
+   * `onDegraded` is called). Defaults to 5 seconds.
+   * @param args.retries - Number of retry attempts for each fetch request.
+   * @param args.maximumConsecutiveFailures - The maximum number of consecutive
+   * failures allowed before breaking the circuit and pausing further updates.
+   * @param args.circuitBreakDuration - The amount of time to wait when the
+   * circuit breaks from too many consecutive failures.
    */
+  constructor(args?: {
+    degradedThreshold?: number;
+    retries?: number;
+    maximumConsecutiveFailures?: number;
+    circuitBreakDuration?: number;
+  });
+
+  /**
+   * Construct a Codefi Token Price Service.
+   *
+   * @deprecated This signature is deprecated; please use the `onBreak` and
+   * `onDegraded` methods instead.
+   * @param args - The arguments.
+   * @param args.degradedThreshold - The length of time (in milliseconds)
+   * that governs when the service is regarded as degraded (affecting when
+   * `onDegraded` is called). Defaults to 5 seconds.
+   * @param args.retries - Number of retry attempts for each fetch request.
+   * @param args.maximumConsecutiveFailures - The maximum number of consecutive
+   * failures allowed before breaking the circuit and pausing further updates.
+   * @param args.onBreak - Callback for when the circuit breaks, useful
+   * for capturing metrics about network failures.
+   * @param args.onDegraded - Callback for when the API responds successfully
+   * but takes too long to respond (5 seconds or more).
+   * @param args.circuitBreakDuration - The amount of time to wait when the
+   * circuit breaks from too many consecutive failures.
+   */
+  // eslint-disable-next-line @typescript-eslint/unified-signatures
+  constructor(args?: {
+    degradedThreshold?: number;
+    retries?: number;
+    maximumConsecutiveFailures?: number;
+    onBreak?: () => void;
+    onDegraded?: () => void;
+    circuitBreakDuration?: number;
+  });
+
   constructor({
     degradedThreshold = DEFAULT_DEGRADED_THRESHOLD,
-    retries = DEFAULT_TOKEN_PRICE_RETRIES,
-    maximumConsecutiveFailures = DEFAULT_TOKEN_PRICE_MAX_CONSECUTIVE_FAILURES,
+    retries = DEFAULT_MAX_RETRIES,
+    maximumConsecutiveFailures = DEFAULT_MAX_CONSECUTIVE_FAILURES,
     onBreak,
     onDegraded,
-    circuitBreakDuration = 30 * 60 * 1000,
+    circuitBreakDuration = DEFAULT_CIRCUIT_BREAK_DURATION,
   }: {
     degradedThreshold?: number;
     retries?: number;
@@ -398,35 +422,40 @@ export class CodefiTokenPricesServiceV2
     onDegraded?: () => void;
     circuitBreakDuration?: number;
   } = {}) {
-    // Construct a policy that will retry each update, and halt further updates
-    // for a certain period after too many consecutive failures.
-    const retryPolicy = retry(handleAll, {
-      maxAttempts: retries,
-      backoff: new ExponentialBackoff(),
-    });
-    const circuitBreakerPolicy = circuitBreaker(handleAll, {
-      halfOpenAfter: circuitBreakDuration,
-      breaker: new ConsecutiveBreaker(maximumConsecutiveFailures),
+    this.#policy = createServicePolicy({
+      maxRetries: retries,
+      maxConsecutiveFailures: maximumConsecutiveFailures,
+      circuitBreakDuration,
+      degradedThreshold,
     });
     if (onBreak) {
-      circuitBreakerPolicy.onBreak(onBreak);
+      this.#policy.onBreak(onBreak);
     }
     if (onDegraded) {
-      retryPolicy.onGiveUp(() => {
-        if (circuitBreakerPolicy.state === CircuitState.Closed) {
-          onDegraded();
-        }
-      });
-      retryPolicy.onSuccess(({ duration }) => {
-        if (
-          circuitBreakerPolicy.state === CircuitState.Closed &&
-          duration > degradedThreshold
-        ) {
-          onDegraded();
-        }
-      });
+      this.#policy.onDegraded(onDegraded);
     }
-    this.#tokenPricePolicy = wrap(retryPolicy, circuitBreakerPolicy);
+  }
+
+  /**
+   * Listens for when the request to the API fails too many times in a row.
+   *
+   * @param args - The same arguments that {@link ServicePolicy.onBreak}
+   * takes.
+   * @returns What {@link ServicePolicy.onBreak} returns.
+   */
+  onBreak(...args: Parameters<ServicePolicy['onBreak']>) {
+    return this.#policy.onBreak(...args);
+  }
+
+  /**
+   * Listens for when the API is degraded.
+   *
+   * @param args - The same arguments that {@link ServicePolicy.onDegraded}
+   * takes.
+   * @returns What {@link ServicePolicy.onDegraded} returns.
+   */
+  onDegraded(...args: Parameters<ServicePolicy['onDegraded']>) {
+    return this.#policy.onDegraded(...args);
   }
 
   /**
@@ -459,7 +488,7 @@ export class CodefiTokenPricesServiceV2
     url.searchParams.append('includeMarketData', 'true');
 
     const addressCryptoDataMap: MarketDataByTokenAddress =
-      await this.#tokenPricePolicy.execute(() =>
+      await this.#policy.execute(() =>
         handleFetch(url, { headers: { 'Cache-Control': 'no-cache' } }),
       );
 
diff --git a/packages/assets-controllers/src/token-prices-service/index.ts b/packages/assets-controllers/src/token-prices-service/index.ts
index 509fc680055..2a69f5890e7 100644
--- a/packages/assets-controllers/src/token-prices-service/index.ts
+++ b/packages/assets-controllers/src/token-prices-service/index.ts
@@ -1,4 +1,4 @@
-export type { AbstractTokenPricesService } from './abstract-token-prices-service';
+export type { IAbstractTokenPricesService } from './abstract-token-prices-service';
 export {
   CodefiTokenPricesServiceV2,
   SUPPORTED_CHAIN_IDS,
diff --git a/packages/remote-feature-flag-controller/CHANGELOG.md b/packages/remote-feature-flag-controller/CHANGELOG.md
index 20df3a0a4ca..b688177db93 100644
--- a/packages/remote-feature-flag-controller/CHANGELOG.md
+++ b/packages/remote-feature-flag-controller/CHANGELOG.md
@@ -7,6 +7,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add `onBreak` and `onDegraded` methods to `ClientConfigApiService` ([#5109](https://github.com/MetaMask/core/pull/5109))
+  - These serve the same purpose as the `onBreak` and `onDegraded` constructor options, but align more closely with the Cockatiel policy API.
+
+### Changed
+
+- Deprecate `ClientConfigApiService` constructor options `onBreak` and `onDegraded` in favor of methods ([#5109](https://github.com/MetaMask/core/pull/5109))
+- Add `@metamask/controller-utils@^11.4.5` as a dependency ([#5109](https://github.com/MetaMask/core/pull/5109))
+  - `cockatiel` should still be in the dependency tree because it's now a dependency of `@metamask/controller-utils`
+
 ## [1.3.0]
 
 ### Changed
diff --git a/packages/remote-feature-flag-controller/package.json b/packages/remote-feature-flag-controller/package.json
index 38128e1b2df..7184fd4a618 100644
--- a/packages/remote-feature-flag-controller/package.json
+++ b/packages/remote-feature-flag-controller/package.json
@@ -48,14 +48,13 @@
   },
   "dependencies": {
     "@metamask/base-controller": "^7.1.1",
+    "@metamask/controller-utils": "^11.4.5",
     "@metamask/utils": "^11.0.1",
-    "cockatiel": "^3.1.2",
     "uuid": "^8.3.2"
   },
   "devDependencies": {
     "@lavamoat/allow-scripts": "^3.0.4",
     "@metamask/auto-changelog": "^3.4.4",
-    "@metamask/controller-utils": "^11.4.5",
     "@types/jest": "^27.4.1",
     "deepmerge": "^4.2.2",
     "jest": "^27.5.1",
diff --git a/packages/remote-feature-flag-controller/src/client-config-api-service/abstract-client-config-api-service.ts b/packages/remote-feature-flag-controller/src/client-config-api-service/abstract-client-config-api-service.ts
index a7def3bef56..ee7c6bf8787 100644
--- a/packages/remote-feature-flag-controller/src/client-config-api-service/abstract-client-config-api-service.ts
+++ b/packages/remote-feature-flag-controller/src/client-config-api-service/abstract-client-config-api-service.ts
@@ -1,9 +1,20 @@
-import type { PublicInterface } from '@metamask/utils';
+import type { ServicePolicy } from '@metamask/controller-utils';
 
-import type { ClientConfigApiService } from './client-config-api-service';
+import type { ServiceResponse } from '../remote-feature-flag-controller-types';
 
 /**
  * A service object responsible for fetching feature flags.
  */
-export type AbstractClientConfigApiService =
-  PublicInterface<ClientConfigApiService>;
+export type IAbstractClientConfigApiService = Partial<
+  Pick<ServicePolicy, 'onBreak' | 'onDegraded'>
+> & {
+  /**
+   * Fetches feature flags from the API with specific client, distribution, and
+   * environment parameters. Provides structured error handling, including
+   * fallback to cached data if available.
+   *
+   * @returns An object of feature flags and their boolean values or a
+   * structured error object.
+   */
+  fetchRemoteFeatureFlags(): Promise<ServiceResponse>;
+};
diff --git a/packages/remote-feature-flag-controller/src/client-config-api-service/client-config-api-service.test.ts b/packages/remote-feature-flag-controller/src/client-config-api-service/client-config-api-service.test.ts
index 1baaaf72bf4..0cd8756d47c 100644
--- a/packages/remote-feature-flag-controller/src/client-config-api-service/client-config-api-service.test.ts
+++ b/packages/remote-feature-flag-controller/src/client-config-api-service/client-config-api-service.test.ts
@@ -20,9 +20,68 @@ const mockFeatureFlags: FeatureFlags = {
   feature2: { chrome: '<109' },
 };
 
+jest.setTimeout(8000);
+
 describe('ClientConfigApiService', () => {
   const networkError = new Error('Network error');
 
+  describe('onBreak', () => {
+    it('should register a listener that is called when the circuit opens', async () => {
+      const onBreak = jest.fn();
+      const mockFetch = createMockFetch({ error: networkError });
+
+      const clientConfigApiService = new ClientConfigApiService({
+        fetch: mockFetch,
+        maximumConsecutiveFailures: 1,
+        config: {
+          client: ClientType.Extension,
+          distribution: DistributionType.Main,
+          environment: EnvironmentType.Production,
+        },
+      });
+      clientConfigApiService.onBreak(onBreak);
+
+      await expect(
+        clientConfigApiService.fetchRemoteFeatureFlags(),
+      ).rejects.toThrow(
+        'Execution prevented because the circuit breaker is open',
+      );
+
+      expect(onBreak).toHaveBeenCalled();
+    });
+  });
+
+  describe('onDegraded', () => {
+    it('should register a listener that is called when the request is slow', async () => {
+      const onDegraded = jest.fn();
+      const slowFetchTime = 5500; // Exceed the DEFAULT_DEGRADED_THRESHOLD (5000ms)
+      // Mock fetch to take a long time
+      const mockSlowFetch = createMockFetch({
+        response: {
+          ok: true,
+          status: 200,
+          json: async () => mockServerFeatureFlagsResponse,
+        },
+        delay: slowFetchTime,
+      });
+
+      const clientConfigApiService = new ClientConfigApiService({
+        fetch: mockSlowFetch,
+        config: {
+          client: ClientType.Extension,
+          distribution: DistributionType.Main,
+          environment: EnvironmentType.Production,
+        },
+      });
+      clientConfigApiService.onDegraded(onDegraded);
+
+      await clientConfigApiService.fetchRemoteFeatureFlags();
+
+      // Verify the degraded callback was called
+      expect(onDegraded).toHaveBeenCalled();
+    }, 7000);
+  });
+
   describe('fetchRemoteFeatureFlags', () => {
     it('fetches successfully and returns feature flags', async () => {
       const mockFetch = createMockFetch({
@@ -132,43 +191,8 @@ describe('ClientConfigApiService', () => {
       // Check that fetch was retried the correct number of times
       expect(mockFetch).toHaveBeenCalledTimes(maxRetries + 1); // Initial + retries
     });
-  });
-
-  describe('circuit breaker', () => {
-    it('opens the circuit breaker after consecutive failures', async () => {
-      const mockFetch = createMockFetch({ error: networkError });
-      const maxFailures = 3;
-      const clientConfigApiService = new ClientConfigApiService({
-        fetch: mockFetch,
-        maximumConsecutiveFailures: maxFailures,
-        config: {
-          client: ClientType.Extension,
-          distribution: DistributionType.Main,
-          environment: EnvironmentType.Production,
-        },
-      });
-
-      // Attempt requests until circuit breaker opens
-      for (let i = 0; i < maxFailures; i++) {
-        await expect(
-          clientConfigApiService.fetchRemoteFeatureFlags(),
-        ).rejects.toThrow(
-          /Network error|Execution prevented because the circuit breaker is open/u,
-        );
-      }
-
-      // Verify the circuit breaker is now open
-      await expect(
-        clientConfigApiService.fetchRemoteFeatureFlags(),
-      ).rejects.toThrow(
-        'Execution prevented because the circuit breaker is open',
-      );
-
-      // Verify fetch was called the expected number of times
-      expect(mockFetch).toHaveBeenCalledTimes(maxFailures);
-    });
 
-    it('should call onBreak when circuit breaker opens', async () => {
+    it('should call the onBreak callback when the circuit opens', async () => {
       const onBreak = jest.fn();
       const mockFetch = createMockFetch({ error: networkError });
 
@@ -192,8 +216,7 @@ describe('ClientConfigApiService', () => {
       expect(onBreak).toHaveBeenCalled();
     });
 
-    it('should call the onDegraded callback when requests are slow', async () => {
-      jest.setTimeout(7000);
+    it('should call the onDegraded callback when the request is slow', async () => {
       const onDegraded = jest.fn();
       const slowFetchTime = 5500; // Exceed the DEFAULT_DEGRADED_THRESHOLD (5000ms)
       // Mock fetch to take a long time
@@ -221,64 +244,6 @@ describe('ClientConfigApiService', () => {
       // Verify the degraded callback was called
       expect(onDegraded).toHaveBeenCalled();
     }, 7000);
-
-    it('should succeed on a subsequent fetch attempt after retries', async () => {
-      const maxRetries = 2;
-      // Mock fetch to fail initially, then succeed
-      const mockFetch = jest
-        .fn()
-        .mockRejectedValueOnce(networkError)
-        .mockRejectedValueOnce(networkError)
-        .mockResolvedValueOnce({
-          ok: true,
-          status: 200,
-          statusText: 'OK',
-          json: async () => mockServerFeatureFlagsResponse,
-        });
-
-      const clientConfigApiService = new ClientConfigApiService({
-        fetch: mockFetch,
-        retries: maxRetries,
-        config: {
-          client: ClientType.Extension,
-          distribution: DistributionType.Main,
-          environment: EnvironmentType.Production,
-        },
-      });
-
-      const result = await clientConfigApiService.fetchRemoteFeatureFlags();
-
-      expect(result).toStrictEqual({
-        remoteFeatureFlags: mockFeatureFlags,
-        cacheTimestamp: expect.any(Number),
-      });
-
-      expect(mockFetch).toHaveBeenCalledTimes(maxRetries + 1);
-    });
-
-    it('calls onDegraded when retries are exhausted and circuit is closed', async () => {
-      const onDegraded = jest.fn();
-      const mockFetch = jest.fn();
-      mockFetch.mockRejectedValue(new Error('Network error'));
-
-      const service = new ClientConfigApiService({
-        fetch: mockFetch,
-        retries: 2,
-        onDegraded,
-        config: {
-          client: ClientType.Extension,
-          distribution: DistributionType.Main,
-          environment: EnvironmentType.Production,
-        },
-      });
-
-      await expect(service.fetchRemoteFeatureFlags()).rejects.toThrow(
-        'Network error',
-      );
-
-      // Should be called once after all retries are exhausted
-      expect(onDegraded).toHaveBeenCalledTimes(1);
-    });
   });
 });
 
diff --git a/packages/remote-feature-flag-controller/src/client-config-api-service/client-config-api-service.ts b/packages/remote-feature-flag-controller/src/client-config-api-service/client-config-api-service.ts
index 7cd9177e0b9..ef525e76954 100644
--- a/packages/remote-feature-flag-controller/src/client-config-api-service/client-config-api-service.ts
+++ b/packages/remote-feature-flag-controller/src/client-config-api-service/client-config-api-service.ts
@@ -1,14 +1,12 @@
 import {
-  circuitBreaker,
-  ConsecutiveBreaker,
-  ExponentialBackoff,
-  handleAll,
-  type IPolicy,
-  retry,
-  wrap,
-  CircuitState,
-} from 'cockatiel';
-
+  createServicePolicy,
+  DEFAULT_CIRCUIT_BREAK_DURATION,
+  DEFAULT_MAX_CONSECUTIVE_FAILURES,
+  DEFAULT_MAX_RETRIES,
+} from '@metamask/controller-utils';
+import type { ServicePolicy } from '@metamask/controller-utils';
+
+import type { IAbstractClientConfigApiService } from './abstract-client-config-api-service';
 import { BASE_URL } from '../constants';
 import type {
   FeatureFlags,
@@ -19,19 +17,13 @@ import type {
   ApiDataResponse,
 } from '../remote-feature-flag-controller-types';
 
-const DEFAULT_FETCH_RETRIES = 3;
-// Each update attempt will result (1 + retries) calls if the server is down
-const DEFAULT_MAX_CONSECUTIVE_FAILURES = (1 + DEFAULT_FETCH_RETRIES) * 3;
-
-export const DEFAULT_DEGRADED_THRESHOLD = 5000;
-
 /**
  * This service is responsible for fetching feature flags from the ClientConfig API.
  */
-export class ClientConfigApiService {
+export class ClientConfigApiService implements IAbstractClientConfigApiService {
   #fetch: typeof fetch;
 
-  #policy: IPolicy;
+  readonly #policy: ServicePolicy;
 
   #client: ClientType;
 
@@ -44,23 +36,83 @@ export class ClientConfigApiService {
    *
    * @param args - The arguments.
    * @param args.fetch - A function that can be used to make an HTTP request.
+   * If your JavaScript environment supports `fetch` natively, you'll probably
+   * want to pass that; otherwise you can pass an equivalent (such as `fetch`
+   * via `node-fetch`).
    * @param args.retries - Number of retry attempts for each fetch request.
-   * @param args.maximumConsecutiveFailures - The maximum number of consecutive failures
-   * allowed before breaking the circuit and pausing further fetch attempts.
-   * @param args.circuitBreakDuration - The duration for which the circuit remains open after
-   * too many consecutive failures.
-   * @param args.onBreak - Callback invoked when the circuit breaks.
-   * @param args.onDegraded - Callback invoked when the service is degraded (requests resolving too slowly).
-   * @param args.config - The configuration object, includes client, distribution, and environment.
+   * @param args.maximumConsecutiveFailures - The maximum number of consecutive
+   * failures allowed before breaking the circuit and pausing further fetch
+   * attempts.
+   * @param args.circuitBreakDuration - The amount of time to wait when the
+   * circuit breaks from too many consecutive failures.
+   * @param args.config - The configuration object, includes client,
+   * distribution, and environment.
    * @param args.config.client - The client type (e.g., 'extension', 'mobile').
-   * @param args.config.distribution - The distribution type (e.g., 'main', 'flask').
-   * @param args.config.environment - The environment type (e.g., 'prod', 'rc', 'dev').
+   * @param args.config.distribution - The distribution type (e.g., 'main',
+   * 'flask').
+   * @param args.config.environment - The environment type (e.g., 'prod', 'rc',
+   * 'dev').
    */
+  constructor(args: {
+    fetch: typeof fetch;
+    retries?: number;
+    maximumConsecutiveFailures?: number;
+    circuitBreakDuration?: number;
+    config: {
+      client: ClientType;
+      distribution: DistributionType;
+      environment: EnvironmentType;
+    };
+  });
+
+  /**
+   * Constructs a new ClientConfigApiService object.
+   *
+   * @deprecated This signature is deprecated; please use the `onBreak` and
+   * `onDegraded` methods instead.
+   * @param args - The arguments.
+   * @param args.fetch - A function that can be used to make an HTTP request.
+   * If your JavaScript environment supports `fetch` natively, you'll probably
+   * want to pass that; otherwise you can pass an equivalent (such as `fetch`
+   * via `node-fetch`).
+   * @param args.retries - Number of retry attempts for each fetch request.
+   * @param args.maximumConsecutiveFailures - The maximum number of consecutive
+   * failures allowed before breaking the circuit and pausing further fetch
+   * attempts.
+   * @param args.circuitBreakDuration - The amount of time to wait when the
+   * circuit breaks from too many consecutive failures.
+   * @param args.onBreak - Callback for when the circuit breaks, useful
+   * for capturing metrics about network failures.
+   * @param args.onDegraded - Callback for when the API responds successfully
+   * but takes too long to respond (5 seconds or more).
+   * @param args.config - The configuration object, includes client,
+   * distribution, and environment.
+   * @param args.config.client - The client type (e.g., 'extension', 'mobile').
+   * @param args.config.distribution - The distribution type (e.g., 'main',
+   * 'flask').
+   * @param args.config.environment - The environment type (e.g., 'prod', 'rc',
+   * 'dev').
+   */
+  // eslint-disable-next-line @typescript-eslint/unified-signatures
+  constructor(args: {
+    fetch: typeof fetch;
+    retries?: number;
+    maximumConsecutiveFailures?: number;
+    circuitBreakDuration?: number;
+    onBreak?: () => void;
+    onDegraded?: () => void;
+    config: {
+      client: ClientType;
+      distribution: DistributionType;
+      environment: EnvironmentType;
+    };
+  });
+
   constructor({
     fetch: fetchFunction,
-    retries = DEFAULT_FETCH_RETRIES,
+    retries = DEFAULT_MAX_RETRIES,
     maximumConsecutiveFailures = DEFAULT_MAX_CONSECUTIVE_FAILURES,
-    circuitBreakDuration = 30 * 60 * 1000,
+    circuitBreakDuration = DEFAULT_CIRCUIT_BREAK_DURATION,
     onBreak,
     onDegraded,
     config,
@@ -82,38 +134,39 @@ export class ClientConfigApiService {
     this.#distribution = config.distribution;
     this.#environment = config.environment;
 
-    const retryPolicy = retry(handleAll, {
-      maxAttempts: retries,
-      backoff: new ExponentialBackoff(),
-    });
-
-    const circuitBreakerPolicy = circuitBreaker(handleAll, {
-      halfOpenAfter: circuitBreakDuration,
-      breaker: new ConsecutiveBreaker(maximumConsecutiveFailures),
+    this.#policy = createServicePolicy({
+      maxRetries: retries,
+      maxConsecutiveFailures: maximumConsecutiveFailures,
+      circuitBreakDuration,
     });
-
     if (onBreak) {
-      circuitBreakerPolicy.onBreak(onBreak);
+      this.#policy.onBreak(onBreak);
     }
-
     if (onDegraded) {
-      retryPolicy.onGiveUp(() => {
-        if (circuitBreakerPolicy.state === CircuitState.Closed) {
-          onDegraded();
-        }
-      });
-
-      retryPolicy.onSuccess(({ duration }) => {
-        if (
-          circuitBreakerPolicy.state === CircuitState.Closed &&
-          duration > DEFAULT_DEGRADED_THRESHOLD // Default degraded threshold
-        ) {
-          onDegraded();
-        }
-      });
+      this.#policy.onDegraded(onDegraded);
     }
+  }
 
-    this.#policy = wrap(retryPolicy, circuitBreakerPolicy);
+  /**
+   * Listens for when the request to the API fails too many times in a row.
+   *
+   * @param args - The same arguments that {@link ServicePolicy.onBreak}
+   * takes.
+   * @returns What {@link ServicePolicy.onBreak} returns.
+   */
+  onBreak(...args: Parameters<ServicePolicy['onBreak']>) {
+    return this.#policy.onBreak(...args);
+  }
+
+  /**
+   * Listens for when the API is degraded.
+   *
+   * @param args - The same arguments that {@link ServicePolicy.onDegraded}
+   * takes.
+   * @returns What {@link ServicePolicy.onDegraded} returns.
+   */
+  onDegraded(...args: Parameters<ServicePolicy['onDegraded']>) {
+    return this.#policy.onDegraded(...args);
   }
 
   /**
diff --git a/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.test.ts b/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.test.ts
index 5def1e901a9..84af924058c 100644
--- a/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.test.ts
+++ b/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.test.ts
@@ -1,6 +1,6 @@
 import { ControllerMessenger } from '@metamask/base-controller';
 
-import type { AbstractClientConfigApiService } from './client-config-api-service/abstract-client-config-api-service';
+import type { IAbstractClientConfigApiService } from './client-config-api-service/abstract-client-config-api-service';
 import {
   RemoteFeatureFlagController,
   controllerName,
@@ -55,7 +55,7 @@ function createController(
   options: Partial<{
     messenger: RemoteFeatureFlagControllerMessenger;
     state: Partial<RemoteFeatureFlagControllerState>;
-    clientConfigApiService: AbstractClientConfigApiService;
+    clientConfigApiService: IAbstractClientConfigApiService;
     disabled: boolean;
     getMetaMetricsId: () => string;
   }> = {},
@@ -218,7 +218,7 @@ describe('RemoteFeatureFlagController', () => {
 
       const clientConfigApiService = {
         fetchRemoteFeatureFlags: fetchSpy,
-      } as AbstractClientConfigApiService;
+      } as IAbstractClientConfigApiService;
 
       const controller = createController({
         clientConfigApiService,
@@ -387,7 +387,7 @@ function buildClientConfigApiService({
   remoteFeatureFlags?: FeatureFlags;
   cacheTimestamp?: number;
   error?: Error;
-} = {}): AbstractClientConfigApiService {
+} = {}): IAbstractClientConfigApiService {
   return {
     fetchRemoteFeatureFlags: jest.fn().mockImplementation(() => {
       if (error) {
diff --git a/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.ts b/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.ts
index 9e370998baa..2664ff1ad90 100644
--- a/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.ts
+++ b/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.ts
@@ -5,7 +5,7 @@ import type {
 } from '@metamask/base-controller';
 import { BaseController } from '@metamask/base-controller';
 
-import type { AbstractClientConfigApiService } from './client-config-api-service/abstract-client-config-api-service';
+import type { IAbstractClientConfigApiService } from './client-config-api-service/abstract-client-config-api-service';
 import type {
   FeatureFlags,
   ServiceResponse,
@@ -98,7 +98,7 @@ export class RemoteFeatureFlagController extends BaseController<
 
   #disabled: boolean;
 
-  #clientConfigApiService: AbstractClientConfigApiService;
+  readonly #clientConfigApiService: IAbstractClientConfigApiService;
 
   #inProgressFlagUpdate?: Promise<ServiceResponse>;
 
@@ -125,7 +125,7 @@ export class RemoteFeatureFlagController extends BaseController<
   }: {
     messenger: RemoteFeatureFlagControllerMessenger;
     state?: Partial<RemoteFeatureFlagControllerState>;
-    clientConfigApiService: AbstractClientConfigApiService;
+    clientConfigApiService: IAbstractClientConfigApiService;
     getMetaMetricsId: () => string;
     fetchInterval?: number;
     disabled?: boolean;
@@ -193,9 +193,7 @@ export class RemoteFeatureFlagController extends BaseController<
    * @private
    */
   async #updateCache(remoteFeatureFlags: FeatureFlags) {
-    const processedRemoteFeatureFlags = await this.#processRemoteFeatureFlags(
-      remoteFeatureFlags,
-    );
+    const processedRemoteFeatureFlags = await this.#processRemoteFeatureFlags(remoteFeatureFlags);
     this.update(() => {
       return {
         remoteFeatureFlags: processedRemoteFeatureFlags,
diff --git a/yarn.lock b/yarn.lock
index c48d3f85a7d..bf510aad60a 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2447,7 +2447,6 @@ __metadata:
     async-mutex: "npm:^0.5.0"
     bitcoin-address-validation: "npm:^2.2.3"
     bn.js: "npm:^5.2.1"
-    cockatiel: "npm:^3.1.2"
     deepmerge: "npm:^4.2.2"
     immer: "npm:^9.0.6"
     jest: "npm:^27.5.1"
@@ -3799,7 +3798,6 @@ __metadata:
     "@metamask/controller-utils": "npm:^11.4.5"
     "@metamask/utils": "npm:^11.0.1"
     "@types/jest": "npm:^27.4.1"
-    cockatiel: "npm:^3.1.2"
     deepmerge: "npm:^4.2.2"
     jest: "npm:^27.5.1"
     nock: "npm:^13.3.1"

From cda581fa2528d2a9695c645091cd2a28e481813e Mon Sep 17 00:00:00 2001
From: Elliot Winkler <elliot.winkler@gmail.com>
Date: Thu, 23 Jan 2025 16:54:13 -0700
Subject: [PATCH 3/3] Remove 'I' prefix from interfaces

---
 .../assets-controllers/src/TokenRatesController.test.ts   | 6 +++---
 packages/assets-controllers/src/TokenRatesController.ts   | 8 ++++----
 packages/assets-controllers/src/assetsUtil.test.ts        | 4 ++--
 packages/assets-controllers/src/assetsUtil.ts             | 6 +++---
 .../token-prices-service/abstract-token-prices-service.ts | 2 +-
 .../src/token-prices-service/codefi-v2.ts                 | 4 ++--
 .../assets-controllers/src/token-prices-service/index.ts  | 2 +-
 .../abstract-client-config-api-service.ts                 | 2 +-
 .../client-config-api-service.ts                          | 4 ++--
 .../src/remote-feature-flag-controller.test.ts            | 8 ++++----
 .../src/remote-feature-flag-controller.ts                 | 6 +++---
 11 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/packages/assets-controllers/src/TokenRatesController.test.ts b/packages/assets-controllers/src/TokenRatesController.test.ts
index 05378c15a80..ee01c088e3d 100644
--- a/packages/assets-controllers/src/TokenRatesController.test.ts
+++ b/packages/assets-controllers/src/TokenRatesController.test.ts
@@ -30,7 +30,7 @@ import {
 } from '../../network-controller/tests/helpers';
 import { TOKEN_PRICES_BATCH_SIZE } from './assetsUtil';
 import type {
-  IAbstractTokenPricesService,
+  AbstractTokenPricesService,
   TokenPrice,
   TokenPricesByTokenAddress,
 } from './token-prices-service/abstract-token-prices-service';
@@ -2754,8 +2754,8 @@ async function callUpdateExchangeRatesMethod({
  * @returns The built mock token prices service.
  */
 function buildMockTokenPricesService(
-  overrides: Partial<IAbstractTokenPricesService> = {},
-): IAbstractTokenPricesService {
+  overrides: Partial<AbstractTokenPricesService> = {},
+): AbstractTokenPricesService {
   return {
     async fetchTokenPrices() {
       return {};
diff --git a/packages/assets-controllers/src/TokenRatesController.ts b/packages/assets-controllers/src/TokenRatesController.ts
index 5bca2809ea0..61f569ee963 100644
--- a/packages/assets-controllers/src/TokenRatesController.ts
+++ b/packages/assets-controllers/src/TokenRatesController.ts
@@ -26,7 +26,7 @@ import { isEqual } from 'lodash';
 
 import { reduceInBatchesSerially, TOKEN_PRICES_BATCH_SIZE } from './assetsUtil';
 import { fetchExchangeRate as fetchNativeCurrencyExchangeRate } from './crypto-compare-service';
-import type { IAbstractTokenPricesService } from './token-prices-service/abstract-token-prices-service';
+import type { AbstractTokenPricesService } from './token-prices-service/abstract-token-prices-service';
 import { getNativeTokenAddress } from './token-prices-service/codefi-v2';
 import type {
   TokensControllerGetStateAction,
@@ -238,7 +238,7 @@ export class TokenRatesController extends StaticIntervalPollingController<TokenR
 
   #pollState = PollState.Inactive;
 
-  readonly #tokenPricesService: IAbstractTokenPricesService;
+  readonly #tokenPricesService: AbstractTokenPricesService;
 
   #inProcessExchangeRateUpdates: Record<`${Hex}:${string}`, Promise<void>> = {};
 
@@ -275,7 +275,7 @@ export class TokenRatesController extends StaticIntervalPollingController<TokenR
   }: {
     interval?: number;
     disabled?: boolean;
-    tokenPricesService: IAbstractTokenPricesService;
+    tokenPricesService: AbstractTokenPricesService;
     messenger: TokenRatesControllerMessenger;
     state?: Partial<TokenRatesControllerState>;
   }) {
@@ -687,7 +687,7 @@ export class TokenRatesController extends StaticIntervalPollingController<TokenR
     let contractNativeInformations;
     const tokenPricesByTokenAddress = await reduceInBatchesSerially<
       Hex,
-      Awaited<ReturnType<IAbstractTokenPricesService['fetchTokenPrices']>>
+      Awaited<ReturnType<AbstractTokenPricesService['fetchTokenPrices']>>
     >({
       values: [...tokenAddresses].sort(),
       batchSize: TOKEN_PRICES_BATCH_SIZE,
diff --git a/packages/assets-controllers/src/assetsUtil.test.ts b/packages/assets-controllers/src/assetsUtil.test.ts
index a40eccfa542..17dc36ebf93 100644
--- a/packages/assets-controllers/src/assetsUtil.test.ts
+++ b/packages/assets-controllers/src/assetsUtil.test.ts
@@ -10,7 +10,7 @@ import { add0x, type Hex } from '@metamask/utils';
 import * as assetsUtil from './assetsUtil';
 import { TOKEN_PRICES_BATCH_SIZE } from './assetsUtil';
 import type { Nft, NftMetadata } from './NftController';
-import type { IAbstractTokenPricesService } from './token-prices-service';
+import type { AbstractTokenPricesService } from './token-prices-service';
 
 const DEFAULT_IPFS_URL_FORMAT = 'ipfs://';
 const ALTERNATIVE_IPFS_URL_FORMAT = 'ipfs://ipfs/';
@@ -772,7 +772,7 @@ function buildAddress(number: number) {
  *
  * @returns The mocked functions of token prices service.
  */
-function createMockPriceService(): IAbstractTokenPricesService {
+function createMockPriceService(): AbstractTokenPricesService {
   return {
     validateChainIdSupported(_chainId: unknown): _chainId is Hex {
       return true;
diff --git a/packages/assets-controllers/src/assetsUtil.ts b/packages/assets-controllers/src/assetsUtil.ts
index 52c0965246d..48b0bcde927 100644
--- a/packages/assets-controllers/src/assetsUtil.ts
+++ b/packages/assets-controllers/src/assetsUtil.ts
@@ -8,7 +8,7 @@ import { remove0x } from '@metamask/utils';
 import BN from 'bn.js';
 
 import type { Nft, NftMetadata } from './NftController';
-import type { IAbstractTokenPricesService } from './token-prices-service';
+import type { AbstractTokenPricesService } from './token-prices-service';
 import { type ContractExchangeRates } from './TokenRatesController';
 
 /**
@@ -387,7 +387,7 @@ export async function fetchTokenContractExchangeRates({
   tokenAddresses,
   chainId,
 }: {
-  tokenPricesService: IAbstractTokenPricesService;
+  tokenPricesService: AbstractTokenPricesService;
   nativeCurrency: string;
   tokenAddresses: Hex[];
   chainId: Hex;
@@ -403,7 +403,7 @@ export async function fetchTokenContractExchangeRates({
 
   const tokenPricesByTokenAddress = await reduceInBatchesSerially<
     Hex,
-    Awaited<ReturnType<IAbstractTokenPricesService['fetchTokenPrices']>>
+    Awaited<ReturnType<AbstractTokenPricesService['fetchTokenPrices']>>
   >({
     values: [...tokenAddresses].sort(),
     batchSize: TOKEN_PRICES_BATCH_SIZE,
diff --git a/packages/assets-controllers/src/token-prices-service/abstract-token-prices-service.ts b/packages/assets-controllers/src/token-prices-service/abstract-token-prices-service.ts
index bac95f74fec..7e705a33ab6 100644
--- a/packages/assets-controllers/src/token-prices-service/abstract-token-prices-service.ts
+++ b/packages/assets-controllers/src/token-prices-service/abstract-token-prices-service.ts
@@ -50,7 +50,7 @@ export type TokenPricesByTokenAddress<
  * @template Currency - A type union of valid arguments for the `currency`
  * argument to `fetchTokenPrices`.
  */
-export type IAbstractTokenPricesService<
+export type AbstractTokenPricesService<
   ChainId extends Hex = Hex,
   TokenAddress extends Hex = Hex,
   Currency extends string = string,
diff --git a/packages/assets-controllers/src/token-prices-service/codefi-v2.ts b/packages/assets-controllers/src/token-prices-service/codefi-v2.ts
index cbc3f05b60f..901d18f7245 100644
--- a/packages/assets-controllers/src/token-prices-service/codefi-v2.ts
+++ b/packages/assets-controllers/src/token-prices-service/codefi-v2.ts
@@ -11,7 +11,7 @@ import type { Hex } from '@metamask/utils';
 import { hexToNumber } from '@metamask/utils';
 
 import type {
-  IAbstractTokenPricesService,
+  AbstractTokenPricesService,
   TokenPrice,
   TokenPricesByTokenAddress,
 } from './abstract-token-prices-service';
@@ -354,7 +354,7 @@ type MarketDataByTokenAddress = { [address: Hex]: MarketData };
  */
 export class CodefiTokenPricesServiceV2
   implements
-    IAbstractTokenPricesService<SupportedChainId, Hex, SupportedCurrency>
+    AbstractTokenPricesService<SupportedChainId, Hex, SupportedCurrency>
 {
   readonly #policy: ServicePolicy;
 
diff --git a/packages/assets-controllers/src/token-prices-service/index.ts b/packages/assets-controllers/src/token-prices-service/index.ts
index 2a69f5890e7..509fc680055 100644
--- a/packages/assets-controllers/src/token-prices-service/index.ts
+++ b/packages/assets-controllers/src/token-prices-service/index.ts
@@ -1,4 +1,4 @@
-export type { IAbstractTokenPricesService } from './abstract-token-prices-service';
+export type { AbstractTokenPricesService } from './abstract-token-prices-service';
 export {
   CodefiTokenPricesServiceV2,
   SUPPORTED_CHAIN_IDS,
diff --git a/packages/remote-feature-flag-controller/src/client-config-api-service/abstract-client-config-api-service.ts b/packages/remote-feature-flag-controller/src/client-config-api-service/abstract-client-config-api-service.ts
index ee7c6bf8787..7a07ed2db9b 100644
--- a/packages/remote-feature-flag-controller/src/client-config-api-service/abstract-client-config-api-service.ts
+++ b/packages/remote-feature-flag-controller/src/client-config-api-service/abstract-client-config-api-service.ts
@@ -5,7 +5,7 @@ import type { ServiceResponse } from '../remote-feature-flag-controller-types';
 /**
  * A service object responsible for fetching feature flags.
  */
-export type IAbstractClientConfigApiService = Partial<
+export type AbstractClientConfigApiService = Partial<
   Pick<ServicePolicy, 'onBreak' | 'onDegraded'>
 > & {
   /**
diff --git a/packages/remote-feature-flag-controller/src/client-config-api-service/client-config-api-service.ts b/packages/remote-feature-flag-controller/src/client-config-api-service/client-config-api-service.ts
index ef525e76954..73e642526d8 100644
--- a/packages/remote-feature-flag-controller/src/client-config-api-service/client-config-api-service.ts
+++ b/packages/remote-feature-flag-controller/src/client-config-api-service/client-config-api-service.ts
@@ -6,7 +6,7 @@ import {
 } from '@metamask/controller-utils';
 import type { ServicePolicy } from '@metamask/controller-utils';
 
-import type { IAbstractClientConfigApiService } from './abstract-client-config-api-service';
+import type { AbstractClientConfigApiService } from './abstract-client-config-api-service';
 import { BASE_URL } from '../constants';
 import type {
   FeatureFlags,
@@ -20,7 +20,7 @@ import type {
 /**
  * This service is responsible for fetching feature flags from the ClientConfig API.
  */
-export class ClientConfigApiService implements IAbstractClientConfigApiService {
+export class ClientConfigApiService implements AbstractClientConfigApiService {
   #fetch: typeof fetch;
 
   readonly #policy: ServicePolicy;
diff --git a/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.test.ts b/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.test.ts
index 84af924058c..5def1e901a9 100644
--- a/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.test.ts
+++ b/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.test.ts
@@ -1,6 +1,6 @@
 import { ControllerMessenger } from '@metamask/base-controller';
 
-import type { IAbstractClientConfigApiService } from './client-config-api-service/abstract-client-config-api-service';
+import type { AbstractClientConfigApiService } from './client-config-api-service/abstract-client-config-api-service';
 import {
   RemoteFeatureFlagController,
   controllerName,
@@ -55,7 +55,7 @@ function createController(
   options: Partial<{
     messenger: RemoteFeatureFlagControllerMessenger;
     state: Partial<RemoteFeatureFlagControllerState>;
-    clientConfigApiService: IAbstractClientConfigApiService;
+    clientConfigApiService: AbstractClientConfigApiService;
     disabled: boolean;
     getMetaMetricsId: () => string;
   }> = {},
@@ -218,7 +218,7 @@ describe('RemoteFeatureFlagController', () => {
 
       const clientConfigApiService = {
         fetchRemoteFeatureFlags: fetchSpy,
-      } as IAbstractClientConfigApiService;
+      } as AbstractClientConfigApiService;
 
       const controller = createController({
         clientConfigApiService,
@@ -387,7 +387,7 @@ function buildClientConfigApiService({
   remoteFeatureFlags?: FeatureFlags;
   cacheTimestamp?: number;
   error?: Error;
-} = {}): IAbstractClientConfigApiService {
+} = {}): AbstractClientConfigApiService {
   return {
     fetchRemoteFeatureFlags: jest.fn().mockImplementation(() => {
       if (error) {
diff --git a/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.ts b/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.ts
index 2664ff1ad90..da206fc1219 100644
--- a/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.ts
+++ b/packages/remote-feature-flag-controller/src/remote-feature-flag-controller.ts
@@ -5,7 +5,7 @@ import type {
 } from '@metamask/base-controller';
 import { BaseController } from '@metamask/base-controller';
 
-import type { IAbstractClientConfigApiService } from './client-config-api-service/abstract-client-config-api-service';
+import type { AbstractClientConfigApiService } from './client-config-api-service/abstract-client-config-api-service';
 import type {
   FeatureFlags,
   ServiceResponse,
@@ -98,7 +98,7 @@ export class RemoteFeatureFlagController extends BaseController<
 
   #disabled: boolean;
 
-  readonly #clientConfigApiService: IAbstractClientConfigApiService;
+  readonly #clientConfigApiService: AbstractClientConfigApiService;
 
   #inProgressFlagUpdate?: Promise<ServiceResponse>;
 
@@ -125,7 +125,7 @@ export class RemoteFeatureFlagController extends BaseController<
   }: {
     messenger: RemoteFeatureFlagControllerMessenger;
     state?: Partial<RemoteFeatureFlagControllerState>;
-    clientConfigApiService: IAbstractClientConfigApiService;
+    clientConfigApiService: AbstractClientConfigApiService;
     getMetaMetricsId: () => string;
     fetchInterval?: number;
     disabled?: boolean;