chore(swingset-liveslots): add retry logic to liveslots-real-gc test (#…

…11015)

refs: #9392

## Description
Adding retry logic to all liveslots-real-gc tests as a temporary workaround to substantially reduce flakiness due to node GC non-determinism.

### Security Considerations
N/A

### Scaling Considerations
some [infrequently] failing tests will get to run twice.

### Documentation Considerations
N/A

### Testing Considerations
Tested manually.

### Upgrade Considerations
N/A

packages/internal/tools/avaRetry.js

@@ -0,0 +1,20 @@
+/**
+ * Run the test and retry once if it fails.
+ *
+ * @param {any} test - AVA test driver function.
+ * @param {string} title - The title of the test.
+ * @param {import('ava').Implementation<unknown[]>} predicate - The test
+ *   implementation.
+ */
+export const avaRetry = (test, title, predicate) => {
+  test(title, async t => {
+    const result = await t.try(predicate);
+    if (result.passed) {
+      result.commit();
+    } else {
+      result.discard();
+      const retryResult = await t.try(predicate);
+      retryResult.commit();
+    }
+  });
+};

packages/swingset-liveslots/test/liveslots-real-gc.test.js

@@ -5,6 +5,7 @@ import test from 'ava';
 import { Far } from '@endo/marshal';
 import { makePromiseKit } from '@endo/promise-kit';
 import { kslot, kser } from '@agoric/kmarshal';
+import { avaRetry } from '@agoric/internal/tools/avaRetry.js';
 import engineGC from './engine-gc.js';
 import { watchCollected, makeGcAndFinalize } from './gc-and-finalize.js';
 import { buildSyscall, makeDispatch } from './liveslots-helpers.js';
@@ -26,7 +27,7 @@ const gcAndFinalize = makeGcAndFinalize(engineGC);
 // inconsistent GC behavior under Node.js and AVA with tests running
 // in parallel, so we mark them all with test.serial()
 
-test.serial('liveslots retains pending exported promise', async t => {
+avaRetry(test.serial, 'liveslots retains pending exported promise', async t => {
   const { log, syscall } = buildSyscall();
   let collected;
   const success = [];
@@ -64,7 +65,7 @@ test.serial('liveslots retains pending exported promise', async t => {
   t.deepEqual(success, ['yes']);
 });
 
-test.serial('liveslots retains device nodes', async t => {
+avaRetry(test.serial, 'liveslots retains device nodes', async t => {
   const { syscall } = buildSyscall();
   let collected;
   const recognize = new WeakSet(); // real WeakSet
@@ -92,7 +93,7 @@ test.serial('liveslots retains device nodes', async t => {
   t.deepEqual(success, [true]);
 });
 
-test.serial('GC syscall.dropImports', async t => {
+avaRetry(test.serial, 'GC syscall.dropImports', async t => {
   const { log, syscall } = buildSyscall();
   let collected;
   function build(_vatPowers) {
@@ -177,7 +178,7 @@ test.serial('GC syscall.dropImports', async t => {
   t.deepEqual(log, []);
 });
 
-test.serial('GC dispatch.retireImports', async t => {
+avaRetry(test.serial, 'GC dispatch.retireImports', async t => {
   const { log, syscall } = buildSyscall();
   function build(_vatPowers) {
     // eslint-disable-next-line no-unused-vars
@@ -210,7 +211,7 @@ test.serial('GC dispatch.retireImports', async t => {
   // when we implement VOM.vrefIsRecognizable, this test might do more
 });
 
-test.serial('GC dispatch.retireExports', async t => {
+avaRetry(test.serial, 'GC dispatch.retireExports', async t => {
   const { log, syscall } = buildSyscall();
   function build(_vatPowers) {
     const ex1 = Far('export', {});
@@ -253,7 +254,7 @@ test.serial('GC dispatch.retireExports', async t => {
   t.deepEqual(log, []);
 });
 
-test.serial('GC dispatch.dropExports', async t => {
+avaRetry(test.serial, 'GC dispatch.dropExports', async t => {
   const { log, syscall } = buildSyscall();
   let collected;
   function build(_vatPowers) {
@@ -326,7 +327,8 @@ test.serial('GC dispatch.dropExports', async t => {
   t.deepEqual(log, []);
 });
 
-test.serial(
+avaRetry(
+  test.serial,
   'GC dispatch.retireExports inhibits syscall.retireExports',
   async t => {
     const { log, syscall } = buildSyscall();