diff --git a/.github/ISSUE_TEMPLATE/fake_async.md b/.github/ISSUE_TEMPLATE/fake_async.md
new file mode 100644
index 000000000..c26edd2ec
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/fake_async.md
@@ -0,0 +1,5 @@
+---
+name: "package:fake_async"
+about: "Create a bug or file a feature request against package:fake_async."
+labels: "package:fake_async"
+---
\ No newline at end of file
diff --git a/.github/workflows/dart.yml b/.github/workflows/dart.yml
index e1b92f73a..6f76daaf7 100644
--- a/.github/workflows/dart.yml
+++ b/.github/workflows/dart.yml
@@ -34,12 +34,42 @@ jobs:
           sdk: stable
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - name: mono_repo self validate
         run: dart pub global activate mono_repo 6.6.2
       - name: mono_repo self validate
         run: dart pub global run mono_repo generate --validate
   job_002:
+    name: "analyze_and_format; linux; Dart 3.3.0; PKG: pkgs/fake_async; `dart analyze`"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Cache Pub hosted dependencies
+        uses: actions/cache@0c45773b623bea8c8e75f6c82b208c3cf94ea4f9
+        with:
+          path: "~/.pub-cache/hosted"
+          key: "os:ubuntu-latest;pub-cache-hosted;sdk:3.3.0;packages:pkgs/fake_async;commands:analyze_1"
+          restore-keys: |
+            os:ubuntu-latest;pub-cache-hosted;sdk:3.3.0;packages:pkgs/fake_async
+            os:ubuntu-latest;pub-cache-hosted;sdk:3.3.0
+            os:ubuntu-latest;pub-cache-hosted
+            os:ubuntu-latest
+      - name: Setup Dart SDK
+        uses: dart-lang/setup-dart@0a8a0fc875eb934c15d08629302413c671d3f672
+        with:
+          sdk: "3.3.0"
+      - id: checkout
+        name: Checkout repository
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
+      - id: pkgs_fake_async_pub_upgrade
+        name: pkgs/fake_async; dart pub upgrade
+        run: dart pub upgrade
+        if: "always() && steps.checkout.conclusion == 'success'"
+        working-directory: pkgs/fake_async
+      - name: pkgs/fake_async; dart analyze
+        run: dart analyze
+        if: "always() && steps.pkgs_fake_async_pub_upgrade.conclusion == 'success'"
+        working-directory: pkgs/fake_async
+  job_003:
     name: "analyze_and_format; linux; Dart 3.5.0-311.0.dev; PKGS: integration_tests/regression, integration_tests/wasm; `dart format --output=none --set-exit-if-changed .`, `dart analyze --fatal-infos`"
     runs-on: ubuntu-latest
     steps:
@@ -59,7 +89,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_regression_pub_upgrade
         name: integration_tests/regression; dart pub upgrade
         run: dart pub upgrade
@@ -86,7 +116,7 @@ jobs:
         run: dart analyze --fatal-infos
         if: "always() && steps.integration_tests_wasm_pub_upgrade.conclusion == 'success'"
         working-directory: integration_tests/wasm
-  job_003:
+  job_004:
     name: "analyze_and_format; linux; Dart 3.5.0-311.0.dev; PKGS: pkgs/checks, pkgs/test_core; `dart analyze`"
     runs-on: ubuntu-latest
     steps:
@@ -106,7 +136,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_checks_pub_upgrade
         name: pkgs/checks; dart pub upgrade
         run: dart pub upgrade
@@ -125,17 +155,17 @@ jobs:
         run: dart analyze
         if: "always() && steps.pkgs_test_core_pub_upgrade.conclusion == 'success'"
         working-directory: pkgs/test_core
-  job_004:
-    name: "analyze_and_format; linux; Dart dev; PKGS: integration_tests/regression, integration_tests/spawn_hybrid, integration_tests/wasm, pkgs/checks, pkgs/test, pkgs/test_api, pkgs/test_core; `dart format --output=none --set-exit-if-changed .`, `dart analyze --fatal-infos`"
+  job_005:
+    name: "analyze_and_format; linux; Dart dev; PKGS: integration_tests/regression, integration_tests/spawn_hybrid, integration_tests/wasm, pkgs/checks, pkgs/fake_async, pkgs/test, pkgs/test_api, pkgs/test_core; `dart format --output=none --set-exit-if-changed .`, `dart analyze --fatal-infos`"
     runs-on: ubuntu-latest
     steps:
       - name: Cache Pub hosted dependencies
         uses: actions/cache@0c45773b623bea8c8e75f6c82b208c3cf94ea4f9
         with:
           path: "~/.pub-cache/hosted"
-          key: "os:ubuntu-latest;pub-cache-hosted;sdk:dev;packages:integration_tests/regression-integration_tests/spawn_hybrid-integration_tests/wasm-pkgs/checks-pkgs/test-pkgs/test_api-pkgs/test_core;commands:format-analyze_0"
+          key: "os:ubuntu-latest;pub-cache-hosted;sdk:dev;packages:integration_tests/regression-integration_tests/spawn_hybrid-integration_tests/wasm-pkgs/checks-pkgs/fake_async-pkgs/test-pkgs/test_api-pkgs/test_core;commands:format-analyze_0"
           restore-keys: |
-            os:ubuntu-latest;pub-cache-hosted;sdk:dev;packages:integration_tests/regression-integration_tests/spawn_hybrid-integration_tests/wasm-pkgs/checks-pkgs/test-pkgs/test_api-pkgs/test_core
+            os:ubuntu-latest;pub-cache-hosted;sdk:dev;packages:integration_tests/regression-integration_tests/spawn_hybrid-integration_tests/wasm-pkgs/checks-pkgs/fake_async-pkgs/test-pkgs/test_api-pkgs/test_core
             os:ubuntu-latest;pub-cache-hosted;sdk:dev
             os:ubuntu-latest;pub-cache-hosted
             os:ubuntu-latest
@@ -145,7 +175,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_regression_pub_upgrade
         name: integration_tests/regression; dart pub upgrade
         run: dart pub upgrade
@@ -198,6 +228,19 @@ jobs:
         run: dart analyze --fatal-infos
         if: "always() && steps.pkgs_checks_pub_upgrade.conclusion == 'success'"
         working-directory: pkgs/checks
+      - id: pkgs_fake_async_pub_upgrade
+        name: pkgs/fake_async; dart pub upgrade
+        run: dart pub upgrade
+        if: "always() && steps.checkout.conclusion == 'success'"
+        working-directory: pkgs/fake_async
+      - name: "pkgs/fake_async; dart format --output=none --set-exit-if-changed ."
+        run: "dart format --output=none --set-exit-if-changed ."
+        if: "always() && steps.pkgs_fake_async_pub_upgrade.conclusion == 'success'"
+        working-directory: pkgs/fake_async
+      - name: "pkgs/fake_async; dart analyze --fatal-infos"
+        run: dart analyze --fatal-infos
+        if: "always() && steps.pkgs_fake_async_pub_upgrade.conclusion == 'success'"
+        working-directory: pkgs/fake_async
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -237,7 +280,7 @@ jobs:
         run: dart analyze --fatal-infos
         if: "always() && steps.pkgs_test_core_pub_upgrade.conclusion == 'success'"
         working-directory: pkgs/test_core
-  job_005:
+  job_006:
     name: "analyze_and_format; windows; Dart 3.5.0-311.0.dev; PKG: integration_tests/wasm; `dart format --output=none --set-exit-if-changed .`, `dart analyze --fatal-infos`"
     runs-on: windows-latest
     steps:
@@ -247,7 +290,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_wasm_pub_upgrade
         name: integration_tests/wasm; dart pub upgrade
         run: dart pub upgrade
@@ -261,7 +304,7 @@ jobs:
         run: dart analyze --fatal-infos
         if: "always() && steps.integration_tests_wasm_pub_upgrade.conclusion == 'success'"
         working-directory: integration_tests/wasm
-  job_006:
+  job_007:
     name: "analyze_and_format; windows; Dart dev; PKG: integration_tests/wasm; `dart format --output=none --set-exit-if-changed .`, `dart analyze --fatal-infos`"
     runs-on: windows-latest
     steps:
@@ -271,7 +314,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_wasm_pub_upgrade
         name: integration_tests/wasm; dart pub upgrade
         run: dart pub upgrade
@@ -285,7 +328,45 @@ jobs:
         run: dart analyze --fatal-infos
         if: "always() && steps.integration_tests_wasm_pub_upgrade.conclusion == 'success'"
         working-directory: integration_tests/wasm
-  job_007:
+  job_008:
+    name: "unit_test; linux; Dart 3.3.0; PKG: pkgs/fake_async; `dart test`"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Cache Pub hosted dependencies
+        uses: actions/cache@0c45773b623bea8c8e75f6c82b208c3cf94ea4f9
+        with:
+          path: "~/.pub-cache/hosted"
+          key: "os:ubuntu-latest;pub-cache-hosted;sdk:3.3.0;packages:pkgs/fake_async;commands:command_00"
+          restore-keys: |
+            os:ubuntu-latest;pub-cache-hosted;sdk:3.3.0;packages:pkgs/fake_async
+            os:ubuntu-latest;pub-cache-hosted;sdk:3.3.0
+            os:ubuntu-latest;pub-cache-hosted
+            os:ubuntu-latest
+      - name: Setup Dart SDK
+        uses: dart-lang/setup-dart@0a8a0fc875eb934c15d08629302413c671d3f672
+        with:
+          sdk: "3.3.0"
+      - id: checkout
+        name: Checkout repository
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
+      - id: pkgs_fake_async_pub_upgrade
+        name: pkgs/fake_async; dart pub upgrade
+        run: dart pub upgrade
+        if: "always() && steps.checkout.conclusion == 'success'"
+        working-directory: pkgs/fake_async
+      - name: pkgs/fake_async; dart test
+        run: dart test
+        if: "always() && steps.pkgs_fake_async_pub_upgrade.conclusion == 'success'"
+        working-directory: pkgs/fake_async
+    needs:
+      - job_001
+      - job_002
+      - job_003
+      - job_004
+      - job_005
+      - job_006
+      - job_007
+  job_009:
     name: "unit_test; linux; Dart 3.5.0-311.0.dev; PKG: integration_tests/regression; `dart test`"
     runs-on: ubuntu-latest
     steps:
@@ -305,7 +386,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_regression_pub_upgrade
         name: integration_tests/regression; dart pub upgrade
         run: dart pub upgrade
@@ -322,7 +403,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_008:
+      - job_007
+  job_010:
     name: "unit_test; linux; Dart 3.5.0-311.0.dev; PKG: pkgs/checks; `dart test`"
     runs-on: ubuntu-latest
     steps:
@@ -342,7 +424,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_checks_pub_upgrade
         name: pkgs/checks; dart pub upgrade
         run: dart pub upgrade
@@ -359,7 +441,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_009:
+      - job_007
+  job_011:
     name: "unit_test; linux; Dart 3.5.0-311.0.dev; PKG: pkgs/test_core; `dart test`"
     runs-on: ubuntu-latest
     steps:
@@ -379,7 +462,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_core_pub_upgrade
         name: pkgs/test_core; dart pub upgrade
         run: dart pub upgrade
@@ -396,7 +479,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_010:
+      - job_007
+  job_012:
     name: "unit_test; linux; Dart 3.5.0-311.0.dev; PKG: integration_tests/spawn_hybrid; `dart test -p chrome,vm,node`"
     runs-on: ubuntu-latest
     steps:
@@ -416,7 +500,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_spawn_hybrid_pub_upgrade
         name: integration_tests/spawn_hybrid; dart pub upgrade
         run: dart pub upgrade
@@ -433,7 +517,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_011:
+      - job_007
+  job_013:
     name: "unit_test; linux; Dart 3.5.0-311.0.dev; PKG: integration_tests/wasm; `dart test --timeout=60s`"
     runs-on: ubuntu-latest
     steps:
@@ -453,7 +538,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_wasm_pub_upgrade
         name: integration_tests/wasm; dart pub upgrade
         run: dart pub upgrade
@@ -470,7 +555,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_012:
+      - job_007
+  job_014:
     name: "unit_test; linux; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `xvfb-run -s \"-screen 0 1024x768x24\" dart test --preset travis --total-shards 5 --shard-index 0`"
     runs-on: ubuntu-latest
     steps:
@@ -490,7 +576,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -507,7 +593,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_013:
+      - job_007
+  job_015:
     name: "unit_test; linux; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `xvfb-run -s \"-screen 0 1024x768x24\" dart test --preset travis --total-shards 5 --shard-index 1`"
     runs-on: ubuntu-latest
     steps:
@@ -527,7 +614,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -544,7 +631,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_014:
+      - job_007
+  job_016:
     name: "unit_test; linux; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `xvfb-run -s \"-screen 0 1024x768x24\" dart test --preset travis --total-shards 5 --shard-index 2`"
     runs-on: ubuntu-latest
     steps:
@@ -564,7 +652,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -581,7 +669,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_015:
+      - job_007
+  job_017:
     name: "unit_test; linux; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `xvfb-run -s \"-screen 0 1024x768x24\" dart test --preset travis --total-shards 5 --shard-index 3`"
     runs-on: ubuntu-latest
     steps:
@@ -601,7 +690,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -618,7 +707,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_016:
+      - job_007
+  job_018:
     name: "unit_test; linux; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `xvfb-run -s \"-screen 0 1024x768x24\" dart test --preset travis --total-shards 5 --shard-index 4`"
     runs-on: ubuntu-latest
     steps:
@@ -638,7 +728,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -655,7 +745,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_017:
+      - job_007
+  job_019:
     name: "unit_test; linux; Dart 3.5.0-311.0.dev; PKG: pkgs/test_api; `dart test --preset travis -x browser`"
     runs-on: ubuntu-latest
     steps:
@@ -675,7 +766,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_api_pub_upgrade
         name: pkgs/test_api; dart pub upgrade
         run: dart pub upgrade
@@ -692,7 +783,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_018:
+      - job_007
+  job_020:
     name: "unit_test; linux; Dart dev; PKG: integration_tests/regression; `dart test`"
     runs-on: ubuntu-latest
     steps:
@@ -712,7 +804,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_regression_pub_upgrade
         name: integration_tests/regression; dart pub upgrade
         run: dart pub upgrade
@@ -729,7 +821,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_019:
+      - job_007
+  job_021:
     name: "unit_test; linux; Dart dev; PKG: pkgs/checks; `dart test`"
     runs-on: ubuntu-latest
     steps:
@@ -749,7 +842,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_checks_pub_upgrade
         name: pkgs/checks; dart pub upgrade
         run: dart pub upgrade
@@ -766,7 +859,46 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_020:
+      - job_007
+  job_022:
+    name: "unit_test; linux; Dart dev; PKG: pkgs/fake_async; `dart test`"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Cache Pub hosted dependencies
+        uses: actions/cache@0c45773b623bea8c8e75f6c82b208c3cf94ea4f9
+        with:
+          path: "~/.pub-cache/hosted"
+          key: "os:ubuntu-latest;pub-cache-hosted;sdk:dev;packages:pkgs/fake_async;commands:command_00"
+          restore-keys: |
+            os:ubuntu-latest;pub-cache-hosted;sdk:dev;packages:pkgs/fake_async
+            os:ubuntu-latest;pub-cache-hosted;sdk:dev
+            os:ubuntu-latest;pub-cache-hosted
+            os:ubuntu-latest
+      - name: Setup Dart SDK
+        uses: dart-lang/setup-dart@0a8a0fc875eb934c15d08629302413c671d3f672
+        with:
+          sdk: dev
+      - id: checkout
+        name: Checkout repository
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
+      - id: pkgs_fake_async_pub_upgrade
+        name: pkgs/fake_async; dart pub upgrade
+        run: dart pub upgrade
+        if: "always() && steps.checkout.conclusion == 'success'"
+        working-directory: pkgs/fake_async
+      - name: pkgs/fake_async; dart test
+        run: dart test
+        if: "always() && steps.pkgs_fake_async_pub_upgrade.conclusion == 'success'"
+        working-directory: pkgs/fake_async
+    needs:
+      - job_001
+      - job_002
+      - job_003
+      - job_004
+      - job_005
+      - job_006
+      - job_007
+  job_023:
     name: "unit_test; linux; Dart dev; PKG: pkgs/test_core; `dart test`"
     runs-on: ubuntu-latest
     steps:
@@ -786,7 +918,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_core_pub_upgrade
         name: pkgs/test_core; dart pub upgrade
         run: dart pub upgrade
@@ -803,7 +935,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_021:
+      - job_007
+  job_024:
     name: "unit_test; linux; Dart dev; PKG: integration_tests/spawn_hybrid; `dart test -p chrome,vm,node`"
     runs-on: ubuntu-latest
     steps:
@@ -823,7 +956,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_spawn_hybrid_pub_upgrade
         name: integration_tests/spawn_hybrid; dart pub upgrade
         run: dart pub upgrade
@@ -840,7 +973,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_022:
+      - job_007
+  job_025:
     name: "unit_test; linux; Dart dev; PKG: integration_tests/wasm; `dart test --timeout=60s`"
     runs-on: ubuntu-latest
     steps:
@@ -860,7 +994,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_wasm_pub_upgrade
         name: integration_tests/wasm; dart pub upgrade
         run: dart pub upgrade
@@ -877,7 +1011,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_023:
+      - job_007
+  job_026:
     name: "unit_test; linux; Dart dev; PKG: pkgs/test; `xvfb-run -s \"-screen 0 1024x768x24\" dart test --preset travis --total-shards 5 --shard-index 0`"
     runs-on: ubuntu-latest
     steps:
@@ -897,7 +1032,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -914,7 +1049,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_024:
+      - job_007
+  job_027:
     name: "unit_test; linux; Dart dev; PKG: pkgs/test; `xvfb-run -s \"-screen 0 1024x768x24\" dart test --preset travis --total-shards 5 --shard-index 1`"
     runs-on: ubuntu-latest
     steps:
@@ -934,7 +1070,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -951,7 +1087,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_025:
+      - job_007
+  job_028:
     name: "unit_test; linux; Dart dev; PKG: pkgs/test; `xvfb-run -s \"-screen 0 1024x768x24\" dart test --preset travis --total-shards 5 --shard-index 2`"
     runs-on: ubuntu-latest
     steps:
@@ -971,7 +1108,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -988,7 +1125,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_026:
+      - job_007
+  job_029:
     name: "unit_test; linux; Dart dev; PKG: pkgs/test; `xvfb-run -s \"-screen 0 1024x768x24\" dart test --preset travis --total-shards 5 --shard-index 3`"
     runs-on: ubuntu-latest
     steps:
@@ -1008,7 +1146,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -1025,7 +1163,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_027:
+      - job_007
+  job_030:
     name: "unit_test; linux; Dart dev; PKG: pkgs/test; `xvfb-run -s \"-screen 0 1024x768x24\" dart test --preset travis --total-shards 5 --shard-index 4`"
     runs-on: ubuntu-latest
     steps:
@@ -1045,7 +1184,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -1062,7 +1201,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_028:
+      - job_007
+  job_031:
     name: "unit_test; linux; Dart dev; PKG: pkgs/test_api; `dart test --preset travis -x browser`"
     runs-on: ubuntu-latest
     steps:
@@ -1082,7 +1222,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_api_pub_upgrade
         name: pkgs/test_api; dart pub upgrade
         run: dart pub upgrade
@@ -1099,7 +1239,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_029:
+      - job_007
+  job_032:
     name: "unit_test; osx; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `dart test --preset travis --total-shards 5 --shard-index 0`"
     runs-on: macos-latest
     steps:
@@ -1119,7 +1260,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -1136,7 +1277,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_030:
+      - job_007
+  job_033:
     name: "unit_test; osx; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `dart test --preset travis --total-shards 5 --shard-index 1`"
     runs-on: macos-latest
     steps:
@@ -1156,7 +1298,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -1173,7 +1315,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_031:
+      - job_007
+  job_034:
     name: "unit_test; osx; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `dart test --preset travis --total-shards 5 --shard-index 2`"
     runs-on: macos-latest
     steps:
@@ -1193,7 +1336,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -1210,7 +1353,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_032:
+      - job_007
+  job_035:
     name: "unit_test; osx; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `dart test --preset travis --total-shards 5 --shard-index 3`"
     runs-on: macos-latest
     steps:
@@ -1230,7 +1374,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -1247,7 +1391,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_033:
+      - job_007
+  job_036:
     name: "unit_test; osx; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `dart test --preset travis --total-shards 5 --shard-index 4`"
     runs-on: macos-latest
     steps:
@@ -1267,7 +1412,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -1284,7 +1429,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_034:
+      - job_007
+  job_037:
     name: "unit_test; windows; Dart 3.5.0-311.0.dev; PKG: integration_tests/spawn_hybrid; `dart test -p chrome,vm,node`"
     runs-on: windows-latest
     steps:
@@ -1294,7 +1440,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_spawn_hybrid_pub_upgrade
         name: integration_tests/spawn_hybrid; dart pub upgrade
         run: dart pub upgrade
@@ -1311,7 +1457,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_035:
+      - job_007
+  job_038:
     name: "unit_test; windows; Dart 3.5.0-311.0.dev; PKG: integration_tests/wasm; `dart test --timeout=60s`"
     runs-on: windows-latest
     steps:
@@ -1321,7 +1468,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_wasm_pub_upgrade
         name: integration_tests/wasm; dart pub upgrade
         run: dart pub upgrade
@@ -1338,7 +1485,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_036:
+      - job_007
+  job_039:
     name: "unit_test; windows; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `dart test --preset travis --total-shards 5 --shard-index 0`"
     runs-on: windows-latest
     steps:
@@ -1348,7 +1496,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -1365,7 +1513,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_037:
+      - job_007
+  job_040:
     name: "unit_test; windows; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `dart test --preset travis --total-shards 5 --shard-index 1`"
     runs-on: windows-latest
     steps:
@@ -1375,7 +1524,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -1392,7 +1541,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_038:
+      - job_007
+  job_041:
     name: "unit_test; windows; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `dart test --preset travis --total-shards 5 --shard-index 2`"
     runs-on: windows-latest
     steps:
@@ -1402,7 +1552,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -1419,7 +1569,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_039:
+      - job_007
+  job_042:
     name: "unit_test; windows; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `dart test --preset travis --total-shards 5 --shard-index 3`"
     runs-on: windows-latest
     steps:
@@ -1429,7 +1580,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -1446,7 +1597,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_040:
+      - job_007
+  job_043:
     name: "unit_test; windows; Dart 3.5.0-311.0.dev; PKG: pkgs/test; `dart test --preset travis --total-shards 5 --shard-index 4`"
     runs-on: windows-latest
     steps:
@@ -1456,7 +1608,7 @@ jobs:
           sdk: "3.5.0-311.0.dev"
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: pkgs_test_pub_upgrade
         name: pkgs/test; dart pub upgrade
         run: dart pub upgrade
@@ -1473,7 +1625,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_041:
+      - job_007
+  job_044:
     name: "unit_test; windows; Dart dev; PKG: integration_tests/spawn_hybrid; `dart test -p chrome,vm,node`"
     runs-on: windows-latest
     steps:
@@ -1483,7 +1636,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_spawn_hybrid_pub_upgrade
         name: integration_tests/spawn_hybrid; dart pub upgrade
         run: dart pub upgrade
@@ -1500,7 +1653,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_042:
+      - job_007
+  job_045:
     name: "unit_test; windows; Dart dev; PKG: integration_tests/wasm; `dart test --timeout=60s`"
     runs-on: windows-latest
     steps:
@@ -1510,7 +1664,7 @@ jobs:
           sdk: dev
       - id: checkout
         name: Checkout repository
-        uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
       - id: integration_tests_wasm_pub_upgrade
         name: integration_tests/wasm; dart pub upgrade
         run: dart pub upgrade
@@ -1527,7 +1681,8 @@ jobs:
       - job_004
       - job_005
       - job_006
-  job_043:
+      - job_007
+  job_046:
     name: Notify failure
     runs-on: ubuntu-latest
     if: "(github.event_name == 'push' || github.event_name == 'schedule') && failure()"
@@ -1581,3 +1736,6 @@ jobs:
       - job_040
       - job_041
       - job_042
+      - job_043
+      - job_044
+      - job_045
diff --git a/README.md b/README.md
index 7091bd97c..df1413b87 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@ literate API.
 | Package | Description | Version |
 |---|---|---|
 | [checks](pkgs/checks/) | A framework for checking values against expectations and building custom expectations. | [![pub package](https://img.shields.io/pub/v/checks.svg)](https://pub.dev/packages/checks) |
+| [fake_async](pkgs/fake_async/) | Fake asynchronous events such as timers and microtasks for deterministic testing. | [![pub package](https://img.shields.io/pub/v/fake_async.svg)](https://pub.dev/packages/fake_async) |
 | [test](pkgs/test/) | A full featured library for writing and running Dart tests across platforms. | [![pub package](https://img.shields.io/pub/v/test.svg)](https://pub.dev/packages/test) |
 | [test_api](pkgs/test_api/) |  | [![pub package](https://img.shields.io/pub/v/test_api.svg)](https://pub.dev/packages/test_api) |
 | [test_core](pkgs/test_core/) |  | [![pub package](https://img.shields.io/pub/v/test_core.svg)](https://pub.dev/packages/test_core) |
diff --git a/pkgs/fake_async/.gitignore b/pkgs/fake_async/.gitignore
new file mode 100644
index 000000000..63fe85d83
--- /dev/null
+++ b/pkgs/fake_async/.gitignore
@@ -0,0 +1,5 @@
+.packages
+.pub/
+.dart_tool/
+build/
+pubspec.lock
diff --git a/pkgs/fake_async/AUTHORS b/pkgs/fake_async/AUTHORS
new file mode 100644
index 000000000..e8063a8cd
--- /dev/null
+++ b/pkgs/fake_async/AUTHORS
@@ -0,0 +1,6 @@
+# Below is a list of people and organizations that have contributed
+# to the project. Names should be added to the list like so:
+#
+#   Name/Organization <email address>
+
+Google Inc.
diff --git a/pkgs/fake_async/CHANGELOG.md b/pkgs/fake_async/CHANGELOG.md
new file mode 100644
index 000000000..0f964eede
--- /dev/null
+++ b/pkgs/fake_async/CHANGELOG.md
@@ -0,0 +1,102 @@
+## 1.3.2
+
+* Require Dart 3.3
+* Fix bug where a `flushTimers` or `elapse` call from within
+  the callback of a periodic timer would immediately invoke
+  the same timer.
+* Move to `dart-lang/test` monorepo.
+* Require Dart 3.5.
+
+## 1.3.1
+
+* Populate the pubspec `repository` field.
+
+## 1.3.0
+
+* `FakeTimer.tick` will return a value instead of throwing.
+* `FakeAsync.includeTimerStackTrace` allows controlling whether timers created
+   with a FakeAsync will include a creation Stack Trace.
+
+## 1.2.0
+
+* Stable release for null safety.
+
+## 1.2.0-nullsafety.3
+
+* Update SDK constraints to `>=2.12.0-0 <3.0.0` based on beta release
+  guidelines.
+
+## 1.2.0-nullsafety.2
+
+* Allow prerelease versions of the 2.12 sdk.
+
+## 1.2.0-nullsafety.1
+
+* Allow 2.10 stable and 2.11.0 dev SDK versions.
+
+## 1.2.0-nullsafety
+
+Pre-release for the null safety migration of this package.
+
+Note that `1.2.0` may not be the final stable null safety release version,
+we reserve the right to release it as a `2.0.0` breaking change.
+
+This release will be pinned to only allow pre-release sdk versions starting
+from `2.10.0-0`.
+
+## 1.1.0
+
+* Exposed the `FakeTimer` class as a public class.
+* Added `FakeAsync.pendingTimers` which gives access to all pending timers at
+  the time of the call.
+
+## 1.0.2
+
+* Update min SDK to 2.2.0
+
+## 1.0.1
+
+* Update to lowercase Dart core library constants.
+* Fix use of deprecated `isInstanceOf` matcher.
+
+## 1.0.0
+
+This release contains the `FakeAsync` class that was defined in [`quiver`][].
+It's backwards-compatible with both the `quiver` version *and* the old version
+of the `fake_async` package.
+
+[`quiver`]: https://pub.dev/packages/quiver
+
+### New Features
+
+* A top-level `fakeAsync()` function was added that encapsulates
+  `new FakeAsync().run(...)`.
+
+### New Features Relative to `quiver`
+
+* `FakeAsync.elapsed` returns the total amount of fake time elapsed since the
+  `FakeAsync` instance was created.
+
+* `new FakeAsync()` now takes an `initialTime` argument that sets the default
+  time for clocks created with `FakeAsync.getClock()`, and for the `clock`
+  package's top-level `clock` variable.
+
+### New Features Relative to `fake_async` 0.1
+
+* `FakeAsync.periodicTimerCount`, `FakeAsync.nonPeriodicTimerCount`, and
+  `FakeAsync.microtaskCount` provide visibility into the events scheduled within
+  `FakeAsync.run()`.
+
+* `FakeAsync.getClock()` provides access to fully-featured `Clock` objects based
+  on `FakeAsync`'s elapsed time.
+
+* `FakeAsync.flushMicrotasks()` empties the microtask queue without elapsing any
+  time or running any timers.
+
+* `FakeAsync.flushTimers()` runs all microtasks and timers until there are no
+  more scheduled.
+
+## 0.1.2
+
+* Integrate with the clock package.
+
diff --git a/pkgs/fake_async/LICENSE b/pkgs/fake_async/LICENSE
new file mode 100644
index 000000000..7a4a3ea24
--- /dev/null
+++ b/pkgs/fake_async/LICENSE
@@ -0,0 +1,202 @@
+
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diff --git a/pkgs/fake_async/README.md b/pkgs/fake_async/README.md
new file mode 100644
index 000000000..c7bb40bf4
--- /dev/null
+++ b/pkgs/fake_async/README.md
@@ -0,0 +1,51 @@
+[![pub package](https://img.shields.io/pub/v/fake_async.svg)](https://pub.dev/packages/fake_async)
+[![package publisher](https://img.shields.io/pub/publisher/fake_async.svg)](https://pub.dev/packages/fake_async/publisher)
+
+This package provides a [`FakeAsync`][] class, which makes it easy to
+deterministically test code that uses asynchronous features like `Future`s,
+`Stream`s, `Timer`s, and microtasks. It creates an environment in which the user
+can explicitly control Dart's notion of the "current time". When the time is
+advanced, `FakeAsync` fires all asynchronous events that are scheduled for that
+time period without actually needing the test to wait for real time to elapse.
+
+[`FakeAsync`]: https://www.dartdocs.org/documentation/fake_async/latest/fake_async/FakeAsync-class.html
+
+For example:
+
+```dart
+import 'dart:async';
+
+import 'package:fake_async/fake_async.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test("Future.timeout() throws an error once the timeout is up", () {
+    // Any code run within [fakeAsync] is run within the context of the
+    // [FakeAsync] object passed to the callback.
+    fakeAsync((async) {
+      // All asynchronous features that rely on timing are automatically
+      // controlled by [fakeAsync].
+      expect(Completer().future.timeout(Duration(seconds: 5)),
+          throwsA(isA<TimeoutException>()));
+
+      // This will cause the timeout above to fire immediately, without waiting
+      // 5 seconds of real time.
+      async.elapse(Duration(seconds: 5));
+    });
+  });
+}
+```
+
+## Integration With `clock`
+
+`FakeAsync` can't control the time reported by [`DateTime.now()`][] or by
+the [`Stopwatch`][] class, since they're not part of `dart:async`. However, if
+you create them using the [`clock`][] package's [`clock.now()`][] or
+[`clock.stopwatch()`][] functions, `FakeAsync` will automatically override
+them to use the same notion of time as `dart:async` classes.
+
+[`DateTime.now()`]: https://api.dart.dev/stable/dart-core/DateTime/DateTime.now.html
+[`Stopwatch`]: https://api.dart.dev/stable/dart-core/Stopwatch-class.html
+[`clock`]: https://pub.dev/packages/clock
+[`clock.now()`]: https://pub.dev/documentation/clock/latest/clock/Clock/now.html
+[`clock.stopwatch()`]: https://pub.dev/documentation/clock/latest/clock/Clock/stopwatch.html
diff --git a/pkgs/fake_async/analysis_options.yaml b/pkgs/fake_async/analysis_options.yaml
new file mode 100644
index 000000000..c0b72ff33
--- /dev/null
+++ b/pkgs/fake_async/analysis_options.yaml
@@ -0,0 +1,22 @@
+include: package:dart_flutter_team_lints/analysis_options.yaml
+analyzer:
+  language:
+    strict-casts: true
+
+linter:
+  rules:
+    - avoid_bool_literals_in_conditional_expressions
+    - avoid_classes_with_only_static_members
+    - avoid_returning_this
+    - avoid_unused_constructor_parameters
+    - cancel_subscriptions
+    - cascade_invocations
+    - comment_references
+    - join_return_with_assignment
+    - literal_only_boolean_expressions
+    - no_adjacent_strings_in_list
+    - package_api_docs
+    - prefer_const_constructors
+    - prefer_final_locals
+    - test_types_in_equals
+    - unnecessary_await_in_return
diff --git a/pkgs/fake_async/lib/fake_async.dart b/pkgs/fake_async/lib/fake_async.dart
new file mode 100644
index 000000000..b4eea856b
--- /dev/null
+++ b/pkgs/fake_async/lib/fake_async.dart
@@ -0,0 +1,332 @@
+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import 'dart:async';
+import 'dart:collection';
+
+import 'package:clock/clock.dart';
+import 'package:collection/collection.dart';
+
+/// The type of a microtask callback.
+typedef _Microtask = void Function();
+
+/// Runs [callback] in a [Zone] where all asynchrony is controlled by an
+/// instance of [FakeAsync].
+///
+/// All [Future]s, [Stream]s, [Timer]s, microtasks, and other time-based
+/// asynchronous features used within [callback] are controlled by calls to
+/// [FakeAsync.elapse] rather than the passing of real time.
+///
+/// The [`clock`][] property will be set to a clock that reports the fake
+/// elapsed time. By default, it starts at the time [fakeAsync] was created
+/// (according to [`clock.now()`][]), but this can be controlled by passing
+/// [initialTime].
+///
+/// [`clock`]: https://www.dartdocs.org/documentation/clock/latest/clock/clock.html
+/// [`clock.now()`]: https://www.dartdocs.org/documentation/clock/latest/clock/Clock/now.html
+///
+/// Returns the result of [callback].
+T fakeAsync<T>(T Function(FakeAsync async) callback, {DateTime? initialTime}) =>
+    FakeAsync(initialTime: initialTime).run(callback);
+
+/// A class that mocks out the passage of time within a [Zone].
+///
+/// Test code can be passed as a callback to [run], which causes it to be run in
+/// a [Zone] which fakes timer and microtask creation, such that they are run
+/// during calls to [elapse] which simulates the asynchronous passage of time.
+///
+/// The synchronous passage of time (as from blocking or expensive calls) can
+/// also be simulated using [elapseBlocking].
+class FakeAsync {
+  /// The value of [clock] within [run].
+  late final Clock _clock;
+
+  /// The amount of fake time that's elapsed since this [FakeAsync] was
+  /// created.
+  Duration get elapsed => _elapsed;
+  var _elapsed = Duration.zero;
+
+  /// Whether Timers created by this FakeAsync will include a creation stack
+  /// trace in [FakeAsync.pendingTimersDebugString].
+  final bool includeTimerStackTrace;
+
+  /// The fake time at which the current call to [elapse] will finish running.
+  ///
+  /// This is `null` if there's no current call to [elapse].
+  Duration? _elapsingTo;
+
+  /// Tasks that are scheduled to run when fake time progresses.
+  final _microtasks = Queue<_Microtask>();
+
+  /// All timers created within [run].
+  final _timers = <FakeTimer>{};
+
+  /// All the current pending timers.
+  List<FakeTimer> get pendingTimers => _timers.toList(growable: false);
+
+  /// The debug strings for all the current pending timers.
+  List<String> get pendingTimersDebugString =>
+      pendingTimers.map((timer) => timer.debugString).toList(growable: false);
+
+  /// The number of active periodic timers created within a call to [run] or
+  /// [fakeAsync].
+  int get periodicTimerCount =>
+      _timers.where((timer) => timer.isPeriodic).length;
+
+  /// The number of active non-periodic timers created within a call to [run] or
+  /// [fakeAsync].
+  int get nonPeriodicTimerCount =>
+      _timers.where((timer) => !timer.isPeriodic).length;
+
+  /// The number of pending microtasks scheduled within a call to [run] or
+  /// [fakeAsync].
+  int get microtaskCount => _microtasks.length;
+
+  /// Creates a [FakeAsync].
+  ///
+  /// Within [run], the [`clock`][] property will start at [initialTime] and
+  /// move forward as fake time elapses.
+  ///
+  /// [`clock`]: https://www.dartdocs.org/documentation/clock/latest/clock/clock.html
+  ///
+  /// Note: it's usually more convenient to use [fakeAsync] rather than creating
+  /// a [FakeAsync] object and calling [run] manually.
+  FakeAsync({DateTime? initialTime, this.includeTimerStackTrace = true}) {
+    final nonNullInitialTime = initialTime ?? clock.now();
+    _clock = Clock(() => nonNullInitialTime.add(elapsed));
+  }
+
+  /// Returns a fake [Clock] whose time can is elapsed by calls to [elapse] and
+  /// [elapseBlocking].
+  ///
+  /// The returned clock starts at [initialTime] plus the fake time that's
+  /// already been elapsed. Further calls to [elapse] and [elapseBlocking] will
+  /// advance the clock as well.
+  ///
+  /// Note that it's usually easier to use the top-level [`clock`][] property.
+  /// Only call this function if you want a different [initialTime] than the
+  /// default.
+  ///
+  /// [`clock`]: https://www.dartdocs.org/documentation/clock/latest/clock/clock.html
+  Clock getClock(DateTime initialTime) =>
+      Clock(() => initialTime.add(_elapsed));
+
+  /// Simulates the asynchronous passage of time.
+  ///
+  /// Throws an [ArgumentError] if [duration] is negative. Throws a [StateError]
+  /// if a previous call to [elapse] has not yet completed.
+  ///
+  /// Any timers created within [run] or [fakeAsync] will fire if their time is
+  /// within [duration]. The microtask queue is processed before and after each
+  /// timer fires.
+  void elapse(Duration duration) {
+    if (duration.inMicroseconds < 0) {
+      throw ArgumentError.value(duration, 'duration', 'may not be negative');
+    } else if (_elapsingTo != null) {
+      throw StateError('Cannot elapse until previous elapse is complete.');
+    }
+
+    _elapsingTo = _elapsed + duration;
+    _fireTimersWhile((next) => next._nextCall <= _elapsingTo!);
+    _elapseTo(_elapsingTo!);
+    _elapsingTo = null;
+  }
+
+  /// Simulates the synchronous passage of time, resulting from blocking or
+  /// expensive calls.
+  ///
+  /// Neither timers nor microtasks are run during this call, but if this is
+  /// called within [elapse] they may fire afterwards.
+  ///
+  /// Throws an [ArgumentError] if [duration] is negative.
+  void elapseBlocking(Duration duration) {
+    if (duration.inMicroseconds < 0) {
+      throw ArgumentError('Cannot call elapse with negative duration');
+    }
+
+    _elapsed += duration;
+    final elapsingTo = _elapsingTo;
+    if (elapsingTo != null && _elapsed > elapsingTo) _elapsingTo = _elapsed;
+  }
+
+  /// Runs [callback] in a [Zone] where all asynchrony is controlled by `this`.
+  ///
+  /// All [Future]s, [Stream]s, [Timer]s, microtasks, and other time-based
+  /// asynchronous features used within [callback] are controlled by calls to
+  /// [elapse] rather than the passing of real time.
+  ///
+  /// The [`clock`][] property will be set to a clock that reports the fake
+  /// elapsed time. By default, it starts at the time the [FakeAsync] was
+  /// created (according to [`clock.now()`][]), but this can be controlled by
+  /// passing `initialTime` to [FakeAsync.new].
+  ///
+  /// [`clock`]: https://www.dartdocs.org/documentation/clock/latest/clock/clock.html
+  /// [`clock.now()`]: https://www.dartdocs.org/documentation/clock/latest/clock/Clock/now.html
+  ///
+  /// Calls [callback] with `this` as argument and returns its result.
+  ///
+  /// Note: it's usually more convenient to use [fakeAsync] rather than creating
+  /// a [FakeAsync] object and calling [run] manually.
+  T run<T>(T Function(FakeAsync self) callback) =>
+      runZoned(() => withClock(_clock, () => callback(this)),
+          zoneSpecification: ZoneSpecification(
+              createTimer: (_, __, ___, duration, callback) =>
+                  _createTimer(duration, callback, false),
+              createPeriodicTimer: (_, __, ___, duration, callback) =>
+                  _createTimer(duration, callback, true),
+              scheduleMicrotask: (_, __, ___, microtask) =>
+                  _microtasks.add(microtask)));
+
+  /// Runs all pending microtasks scheduled within a call to [run] or
+  /// [fakeAsync] until there are no more microtasks scheduled.
+  ///
+  /// Does not run timers.
+  void flushMicrotasks() {
+    while (_microtasks.isNotEmpty) {
+      _microtasks.removeFirst()();
+    }
+  }
+
+  /// Elapses time until there are no more active timers.
+  ///
+  /// If `flushPeriodicTimers` is `true` (the default), this will repeatedly run
+  /// periodic timers until they're explicitly canceled. Otherwise, this will
+  /// stop when the only active timers are periodic.
+  ///
+  /// The [timeout] controls how much fake time may elapse before a [StateError]
+  /// is thrown. This ensures that a periodic timer doesn't cause this method to
+  /// deadlock. It defaults to one hour.
+  void flushTimers(
+      {Duration timeout = const Duration(hours: 1),
+      bool flushPeriodicTimers = true}) {
+    final absoluteTimeout = _elapsed + timeout;
+    _fireTimersWhile((timer) {
+      if (timer._nextCall > absoluteTimeout) {
+        // TODO(nweiz): Make this a [TimeoutException].
+        throw StateError('Exceeded timeout $timeout while flushing timers');
+      }
+
+      if (flushPeriodicTimers) return _timers.isNotEmpty;
+
+      // Continue firing timers until the only ones left are periodic *and*
+      // every periodic timer has had a change to run against the final
+      // value of [_elapsed].
+      return _timers
+          .any((timer) => !timer.isPeriodic || timer._nextCall <= _elapsed);
+    });
+  }
+
+  /// Invoke the callback for each timer until [predicate] returns `false` for
+  /// the next timer that would be fired.
+  ///
+  /// Microtasks are flushed before and after each timer is fired. Before each
+  /// timer fires, [_elapsed] is updated to the appropriate duration.
+  void _fireTimersWhile(bool Function(FakeTimer timer) predicate) {
+    flushMicrotasks();
+    for (;;) {
+      if (_timers.isEmpty) break;
+
+      final timer = minBy(_timers, (FakeTimer timer) => timer._nextCall)!;
+      if (!predicate(timer)) break;
+
+      _elapseTo(timer._nextCall);
+      timer._fire();
+      flushMicrotasks();
+    }
+  }
+
+  /// Creates a new timer controlled by `this` that fires [callback] after
+  /// [duration] (or every [duration] if [periodic] is `true`).
+  Timer _createTimer(Duration duration, Function callback, bool periodic) {
+    final timer = FakeTimer._(duration, callback, periodic, this,
+        includeStackTrace: includeTimerStackTrace);
+    _timers.add(timer);
+    return timer;
+  }
+
+  /// Sets [_elapsed] to [to] if [to] is longer than [_elapsed].
+  void _elapseTo(Duration to) {
+    if (to > _elapsed) _elapsed = to;
+  }
+}
+
+/// An implementation of [Timer] that's controlled by a [FakeAsync].
+class FakeTimer implements Timer {
+  /// If this is periodic, the time that should elapse between firings of this
+  /// timer.
+  ///
+  /// This is not used by non-periodic timers.
+  final Duration duration;
+
+  /// The callback to invoke when the timer fires.
+  ///
+  /// For periodic timers, this is a `void Function(Timer)`. For non-periodic
+  /// timers, it's a `void Function()`.
+  final Function _callback;
+
+  /// Whether this is a periodic timer.
+  final bool isPeriodic;
+
+  /// The [FakeAsync] instance that controls this timer.
+  final FakeAsync _async;
+
+  /// The value of [FakeAsync._elapsed] at (or after) which this timer should be
+  /// fired.
+  late Duration _nextCall;
+
+  /// The current stack trace when this timer was created.
+  ///
+  /// If [FakeAsync.includeTimerStackTrace] is set to false then accessing
+  /// this field will throw a [TypeError].
+  StackTrace get creationStackTrace => _creationStackTrace!;
+  final StackTrace? _creationStackTrace;
+
+  var _tick = 0;
+
+  @override
+  int get tick => _tick;
+
+  /// Returns debugging information to try to identify the source of the
+  /// [Timer].
+  String get debugString => 'Timer (duration: $duration, periodic: $isPeriodic)'
+      '${_creationStackTrace != null ? ', created:\n$creationStackTrace' : ''}';
+
+  FakeTimer._(Duration duration, this._callback, this.isPeriodic, this._async,
+      {bool includeStackTrace = true})
+      : duration = duration < Duration.zero ? Duration.zero : duration,
+        _creationStackTrace = includeStackTrace ? StackTrace.current : null {
+    _nextCall = _async._elapsed + this.duration;
+  }
+
+  @override
+  bool get isActive => _async._timers.contains(this);
+
+  @override
+  void cancel() => _async._timers.remove(this);
+
+  /// Fires this timer's callback and updates its state as necessary.
+  void _fire() {
+    assert(isActive);
+    _tick++;
+    if (isPeriodic) {
+      _nextCall += duration;
+      // ignore: avoid_dynamic_calls
+      _callback(this);
+    } else {
+      cancel();
+      // ignore: avoid_dynamic_calls
+      _callback();
+    }
+  }
+}
diff --git a/pkgs/fake_async/mono_pkg.yaml b/pkgs/fake_async/mono_pkg.yaml
new file mode 100644
index 000000000..b447edbf8
--- /dev/null
+++ b/pkgs/fake_async/mono_pkg.yaml
@@ -0,0 +1,15 @@
+# See https://pub.dev/packages/mono_repo
+
+stages:
+- analyze_and_format:
+  - group:
+    - format
+    - analyze: --fatal-infos
+    sdk: dev
+  - group:
+    - analyze
+    sdk: pubspec
+- unit_test:
+  - group:
+    - command: dart test
+    sdk: [dev, pubspec]
diff --git a/pkgs/fake_async/pubspec.yaml b/pkgs/fake_async/pubspec.yaml
new file mode 100644
index 000000000..f345860ba
--- /dev/null
+++ b/pkgs/fake_async/pubspec.yaml
@@ -0,0 +1,17 @@
+name: fake_async
+version: 1.3.2
+description: >-
+  Fake asynchronous events such as timers and microtasks for deterministic
+  testing.
+repository: https://github.com/dart-lang/test/tree/master/pkgs/fake_async
+environment:
+  sdk: ^3.3.0
+
+dependencies:
+  clock: ^1.1.0
+  collection: ^1.15.0
+
+dev_dependencies:
+  async: ^2.5.0
+  dart_flutter_team_lints: ^2.0.0
+  test: ^1.16.0
diff --git a/pkgs/fake_async/test/fake_async_test.dart b/pkgs/fake_async/test/fake_async_test.dart
new file mode 100644
index 000000000..463eecdb8
--- /dev/null
+++ b/pkgs/fake_async/test/fake_async_test.dart
@@ -0,0 +1,663 @@
+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import 'dart:async';
+
+import 'package:clock/clock.dart';
+import 'package:fake_async/fake_async.dart';
+import 'package:test/test.dart';
+
+void main() {
+  final initialTime = DateTime(2000);
+  final elapseBy = const Duration(days: 1);
+
+  test('should set initial time', () {
+    expect(FakeAsync().getClock(initialTime).now(), initialTime);
+  });
+
+  group('elapseBlocking', () {
+    test('should elapse time without calling timers', () {
+      Timer(elapseBy ~/ 2, neverCalled);
+      FakeAsync().elapseBlocking(elapseBy);
+    });
+
+    test('should elapse time by the specified amount', () {
+      final async = FakeAsync()..elapseBlocking(elapseBy);
+      expect(async.elapsed, elapseBy);
+    });
+
+    test('should throw when called with a negative duration', () {
+      expect(() => FakeAsync().elapseBlocking(const Duration(days: -1)),
+          throwsArgumentError);
+    });
+  });
+
+  group('elapse', () {
+    test('should elapse time by the specified amount', () {
+      FakeAsync().run((async) {
+        async.elapse(elapseBy);
+        expect(async.elapsed, elapseBy);
+      });
+    });
+
+    test('should throw ArgumentError when called with a negative duration', () {
+      expect(() => FakeAsync().elapse(const Duration(days: -1)),
+          throwsArgumentError);
+    });
+
+    test('should throw when called before previous call is complete', () {
+      FakeAsync().run((async) {
+        Timer(elapseBy ~/ 2, expectAsync0(() {
+          expect(() => async.elapse(elapseBy), throwsStateError);
+        }));
+        async.elapse(elapseBy);
+      });
+    });
+
+    group('when creating timers', () {
+      test('should call timers expiring before or at end time', () {
+        FakeAsync().run((async) {
+          Timer(elapseBy ~/ 2, expectAsync0(() {}));
+          Timer(elapseBy, expectAsync0(() {}));
+          async.elapse(elapseBy);
+        });
+      });
+
+      test('should call timers expiring due to elapseBlocking', () {
+        FakeAsync().run((async) {
+          Timer(elapseBy, () => async.elapseBlocking(elapseBy));
+          Timer(elapseBy * 2, expectAsync0(() {}));
+          async.elapse(elapseBy);
+          expect(async.elapsed, elapseBy * 2);
+        });
+      });
+
+      test('should call timers at their scheduled time', () {
+        FakeAsync().run((async) {
+          Timer(elapseBy ~/ 2, expectAsync0(() {
+            expect(async.elapsed, elapseBy ~/ 2);
+          }));
+
+          final periodicCalledAt = <Duration>[];
+          Timer.periodic(
+              elapseBy ~/ 2, (_) => periodicCalledAt.add(async.elapsed));
+
+          async.elapse(elapseBy);
+          expect(periodicCalledAt, [elapseBy ~/ 2, elapseBy]);
+        });
+      });
+
+      test('should not call timers expiring after end time', () {
+        FakeAsync().run((async) {
+          Timer(elapseBy * 2, neverCalled);
+          async.elapse(elapseBy);
+        });
+      });
+
+      test('should not call canceled timers', () {
+        FakeAsync().run((async) {
+          Timer(elapseBy ~/ 2, neverCalled).cancel();
+          async.elapse(elapseBy);
+        });
+      });
+
+      test('should call periodic timers each time the duration elapses', () {
+        FakeAsync().run((async) {
+          Timer.periodic(elapseBy ~/ 10, expectAsync1((_) {}, count: 10));
+          async.elapse(elapseBy);
+        });
+      });
+
+      test('should call timers occurring at the same time in FIFO order', () {
+        FakeAsync().run((async) {
+          final log = <String>[];
+          Timer(elapseBy ~/ 2, () => log.add('1'));
+          Timer(elapseBy ~/ 2, () => log.add('2'));
+          async.elapse(elapseBy);
+          expect(log, ['1', '2']);
+        });
+      });
+
+      test('should maintain FIFO order even with periodic timers', () {
+        FakeAsync().run((async) {
+          final log = <String>[];
+          Timer.periodic(elapseBy ~/ 2, (_) => log.add('periodic 1'));
+          Timer(elapseBy ~/ 2, () => log.add('delayed 1'));
+          Timer(elapseBy, () => log.add('delayed 2'));
+          Timer.periodic(elapseBy, (_) => log.add('periodic 2'));
+
+          async.elapse(elapseBy);
+          expect(log, [
+            'periodic 1',
+            'delayed 1',
+            'periodic 1',
+            'delayed 2',
+            'periodic 2'
+          ]);
+        });
+      });
+
+      test('should process microtasks surrounding each timer', () {
+        FakeAsync().run((async) {
+          var microtaskCalls = 0;
+          var timerCalls = 0;
+          void scheduleMicrotasks() {
+            for (var i = 0; i < 5; i++) {
+              scheduleMicrotask(() => microtaskCalls++);
+            }
+          }
+
+          scheduleMicrotasks();
+          Timer.periodic(elapseBy ~/ 5, (_) {
+            timerCalls++;
+            expect(microtaskCalls, 5 * timerCalls);
+            scheduleMicrotasks();
+          });
+          async.elapse(elapseBy);
+          expect(timerCalls, 5);
+          expect(microtaskCalls, 5 * (timerCalls + 1));
+        });
+      });
+
+      test('should pass the periodic timer itself to callbacks', () {
+        FakeAsync().run((async) {
+          late Timer constructed;
+          constructed = Timer.periodic(elapseBy, expectAsync1((passed) {
+            expect(passed, same(constructed));
+          }));
+          async.elapse(elapseBy);
+        });
+      });
+
+      test('should call microtasks before advancing time', () {
+        FakeAsync().run((async) {
+          scheduleMicrotask(expectAsync0(() {
+            expect(async.elapsed, Duration.zero);
+          }));
+          async.elapse(const Duration(minutes: 1));
+        });
+      });
+
+      test('should add event before advancing time', () {
+        FakeAsync().run((async) {
+          final controller = StreamController<void>();
+          expect(controller.stream.first.then((_) {
+            expect(async.elapsed, Duration.zero);
+          }), completes);
+          controller.add(null);
+          async.elapse(const Duration(minutes: 1));
+        });
+      });
+
+      test('should increase negative duration timers to zero duration', () {
+        FakeAsync().run((async) {
+          final negativeDuration = const Duration(days: -1);
+          Timer(negativeDuration, expectAsync0(() {
+            expect(async.elapsed, Duration.zero);
+          }));
+          async.elapse(const Duration(minutes: 1));
+        });
+      });
+
+      test('should not be additive with elapseBlocking', () {
+        FakeAsync().run((async) {
+          Timer(Duration.zero, () => async.elapseBlocking(elapseBy * 5));
+          async.elapse(elapseBy);
+          expect(async.elapsed, elapseBy * 5);
+        });
+      });
+
+      group('isActive', () {
+        test('should be false after timer is run', () {
+          FakeAsync().run((async) {
+            final timer = Timer(elapseBy ~/ 2, () {});
+            async.elapse(elapseBy);
+            expect(timer.isActive, isFalse);
+          });
+        });
+
+        test('should be true after periodic timer is run', () {
+          FakeAsync().run((async) {
+            final timer = Timer.periodic(elapseBy ~/ 2, (_) {});
+            async.elapse(elapseBy);
+            expect(timer.isActive, isTrue);
+          });
+        });
+
+        test('should be false after timer is canceled', () {
+          FakeAsync().run((async) {
+            final timer = Timer(elapseBy ~/ 2, () {})..cancel();
+            expect(timer.isActive, isFalse);
+          });
+        });
+      });
+
+      test('should work with new Future()', () {
+        FakeAsync().run((async) {
+          Future(expectAsync0(() {}));
+          async.elapse(Duration.zero);
+        });
+      });
+
+      test('should work with Future.delayed', () {
+        FakeAsync().run((async) {
+          Future.delayed(elapseBy, expectAsync0(() {}));
+          async.elapse(elapseBy);
+        });
+      });
+
+      test('should work with Future.timeout', () {
+        FakeAsync().run((async) {
+          final completer = Completer<void>();
+          expect(completer.future.timeout(elapseBy ~/ 2),
+              throwsA(const TypeMatcher<TimeoutException>()));
+          async.elapse(elapseBy);
+          completer.complete();
+        });
+      });
+
+      // TODO: Pausing and resuming the timeout Stream doesn't work since
+      // it uses `new Stopwatch()`.
+      //
+      // See https://code.google.com/p/dart/issues/detail?id=18149
+      test('should work with Stream.periodic', () {
+        FakeAsync().run((async) {
+          expect(Stream.periodic(const Duration(minutes: 1), (i) => i),
+              emitsInOrder([0, 1, 2]));
+          async.elapse(const Duration(minutes: 3));
+        });
+      });
+
+      test('should work with Stream.timeout', () {
+        FakeAsync().run((async) {
+          final controller = StreamController<int>();
+          final timed = controller.stream.timeout(const Duration(minutes: 2));
+
+          final events = <int>[];
+          final errors = <Object>[];
+          timed.listen(events.add, onError: errors.add);
+
+          controller.add(0);
+          async.elapse(const Duration(minutes: 1));
+          expect(events, [0]);
+
+          async.elapse(const Duration(minutes: 1));
+          expect(errors, hasLength(1));
+          expect(errors.first, const TypeMatcher<TimeoutException>());
+        });
+      });
+    });
+  });
+
+  group('flushMicrotasks', () {
+    test('should flush a microtask', () {
+      FakeAsync().run((async) {
+        Future.microtask(expectAsync0(() {}));
+        async.flushMicrotasks();
+      });
+    });
+
+    test('should flush microtasks scheduled by microtasks in order', () {
+      FakeAsync().run((async) {
+        final log = <int>[];
+        scheduleMicrotask(() {
+          log.add(1);
+          scheduleMicrotask(() => log.add(3));
+        });
+        scheduleMicrotask(() => log.add(2));
+
+        async.flushMicrotasks();
+        expect(log, [1, 2, 3]);
+      });
+    });
+
+    test('should not run timers', () {
+      FakeAsync().run((async) {
+        final log = <int>[];
+        scheduleMicrotask(() => log.add(1));
+        Timer.run(() => log.add(2));
+        Timer.periodic(const Duration(seconds: 1), (_) => log.add(2));
+
+        async.flushMicrotasks();
+        expect(log, [1]);
+      });
+    });
+  });
+
+  group('flushTimers', () {
+    test('should flush timers in FIFO order', () {
+      FakeAsync().run((async) {
+        final log = <int>[];
+        Timer.run(() {
+          log.add(1);
+          Timer(elapseBy, () => log.add(3));
+        });
+        Timer.run(() => log.add(2));
+
+        async.flushTimers(timeout: elapseBy * 2);
+        expect(log, [1, 2, 3]);
+        expect(async.elapsed, elapseBy);
+      });
+    });
+
+    test(
+        'should run collateral periodic timers with non-periodic first if '
+        'scheduled first', () {
+      FakeAsync().run((async) {
+        final log = <String>[];
+        Timer(const Duration(seconds: 2), () => log.add('delayed'));
+        Timer.periodic(const Duration(seconds: 1), (_) => log.add('periodic'));
+
+        async.flushTimers(flushPeriodicTimers: false);
+        expect(log, ['periodic', 'delayed', 'periodic']);
+      });
+    });
+
+    test(
+        'should run collateral periodic timers with periodic first '
+        'if scheduled first', () {
+      FakeAsync().run((async) {
+        final log = <String>[];
+        Timer.periodic(const Duration(seconds: 1), (_) => log.add('periodic'));
+        Timer(const Duration(seconds: 2), () => log.add('delayed'));
+
+        async.flushTimers(flushPeriodicTimers: false);
+        expect(log, ['periodic', 'periodic', 'delayed']);
+      });
+    });
+
+    test('should time out', () {
+      FakeAsync().run((async) {
+        // Schedule 3 timers. All but the last one should fire.
+        for (var delay in [30, 60, 90]) {
+          Timer(Duration(minutes: delay),
+              expectAsync0(() {}, count: delay == 90 ? 0 : 1));
+        }
+
+        expect(() => async.flushTimers(), throwsStateError);
+      });
+    });
+
+    test('should time out a chain of timers', () {
+      FakeAsync().run((async) {
+        var count = 0;
+        void createTimer() {
+          Timer(const Duration(minutes: 30), () {
+            count++;
+            createTimer();
+          });
+        }
+
+        createTimer();
+        expect(() => async.flushTimers(timeout: const Duration(hours: 2)),
+            throwsStateError);
+        expect(count, 4);
+      });
+    });
+
+    test('should time out periodic timers', () {
+      FakeAsync().run((async) {
+        Timer.periodic(
+            const Duration(minutes: 30), expectAsync1((_) {}, count: 2));
+        expect(() => async.flushTimers(timeout: const Duration(hours: 1)),
+            throwsStateError);
+      });
+    });
+
+    test('should flush periodic timers', () {
+      FakeAsync().run((async) {
+        var count = 0;
+        Timer.periodic(const Duration(minutes: 30), (timer) {
+          if (count == 3) timer.cancel();
+          count++;
+        });
+        async.flushTimers(timeout: const Duration(hours: 20));
+        expect(count, 4);
+      });
+    });
+
+    test('should compute absolute timeout as elapsed + timeout', () {
+      FakeAsync().run((async) {
+        var count = 0;
+        void createTimer() {
+          Timer(const Duration(minutes: 30), () {
+            count++;
+            if (count < 4) createTimer();
+          });
+        }
+
+        createTimer();
+        async
+          ..elapse(const Duration(hours: 1))
+          ..flushTimers(timeout: const Duration(hours: 1));
+        expect(count, 4);
+      });
+    });
+  });
+
+  group('stats', () {
+    test('should report the number of pending microtasks', () {
+      FakeAsync().run((async) {
+        expect(async.microtaskCount, 0);
+        scheduleMicrotask(() {});
+        expect(async.microtaskCount, 1);
+        scheduleMicrotask(() {});
+        expect(async.microtaskCount, 2);
+        async.flushMicrotasks();
+        expect(async.microtaskCount, 0);
+      });
+    });
+
+    test('it should report the number of pending periodic timers', () {
+      FakeAsync().run((async) {
+        expect(async.periodicTimerCount, 0);
+        final timer = Timer.periodic(const Duration(minutes: 30), (_) {});
+        expect(async.periodicTimerCount, 1);
+        Timer.periodic(const Duration(minutes: 20), (_) {});
+        expect(async.periodicTimerCount, 2);
+        async.elapse(const Duration(minutes: 20));
+        expect(async.periodicTimerCount, 2);
+        timer.cancel();
+        expect(async.periodicTimerCount, 1);
+      });
+    });
+
+    test('it should report the number of pending non periodic timers', () {
+      FakeAsync().run((async) {
+        expect(async.nonPeriodicTimerCount, 0);
+        final timer = Timer(const Duration(minutes: 30), () {});
+        expect(async.nonPeriodicTimerCount, 1);
+        Timer(const Duration(minutes: 20), () {});
+        expect(async.nonPeriodicTimerCount, 2);
+        async.elapse(const Duration(minutes: 25));
+        expect(async.nonPeriodicTimerCount, 1);
+        timer.cancel();
+        expect(async.nonPeriodicTimerCount, 0);
+      });
+    });
+
+    test('should report debugging information of pending timers', () {
+      FakeAsync().run((fakeAsync) {
+        expect(fakeAsync.pendingTimers, isEmpty);
+        final nonPeriodic =
+            Timer(const Duration(seconds: 1), () {}) as FakeTimer;
+        final periodic =
+            Timer.periodic(const Duration(seconds: 2), (Timer timer) {})
+                as FakeTimer;
+        final debugInfo = fakeAsync.pendingTimers;
+        expect(debugInfo.length, 2);
+        expect(
+          debugInfo,
+          containsAll([
+            nonPeriodic,
+            periodic,
+          ]),
+        );
+
+        const thisFileName = 'fake_async_test.dart';
+        expect(nonPeriodic.debugString, contains(':01.0'));
+        expect(nonPeriodic.debugString, contains('periodic: false'));
+        expect(nonPeriodic.debugString, contains(thisFileName));
+        expect(periodic.debugString, contains(':02.0'));
+        expect(periodic.debugString, contains('periodic: true'));
+        expect(periodic.debugString, contains(thisFileName));
+      });
+    });
+
+    test(
+        'should report debugging information of pending timers excluding '
+        'stack traces', () {
+      FakeAsync(includeTimerStackTrace: false).run((fakeAsync) {
+        expect(fakeAsync.pendingTimers, isEmpty);
+        final nonPeriodic =
+            Timer(const Duration(seconds: 1), () {}) as FakeTimer;
+        final periodic =
+            Timer.periodic(const Duration(seconds: 2), (Timer timer) {})
+                as FakeTimer;
+        final debugInfo = fakeAsync.pendingTimers;
+        expect(debugInfo.length, 2);
+        expect(
+          debugInfo,
+          containsAll([
+            nonPeriodic,
+            periodic,
+          ]),
+        );
+
+        const thisFileName = 'fake_async_test.dart';
+        expect(nonPeriodic.debugString, contains(':01.0'));
+        expect(nonPeriodic.debugString, contains('periodic: false'));
+        expect(nonPeriodic.debugString, isNot(contains(thisFileName)));
+        expect(periodic.debugString, contains(':02.0'));
+        expect(periodic.debugString, contains('periodic: true'));
+        expect(periodic.debugString, isNot(contains(thisFileName)));
+      });
+    });
+  });
+
+  group('timers', () {
+    test("should become inactive as soon as they're invoked", () {
+      return FakeAsync().run((async) {
+        late Timer timer;
+        timer = Timer(elapseBy, expectAsync0(() {
+          expect(timer.isActive, isFalse);
+        }));
+
+        expect(timer.isActive, isTrue);
+        async.elapse(elapseBy);
+        expect(timer.isActive, isFalse);
+      });
+    });
+
+    test('should increment tick in a non-periodic timer', () {
+      return FakeAsync().run((async) {
+        late Timer timer;
+        timer = Timer(elapseBy, expectAsync0(() {
+          expect(timer.tick, 1);
+        }));
+
+        expect(timer.tick, 0);
+        async.elapse(elapseBy);
+      });
+    });
+
+    test('should increment tick in a periodic timer', () {
+      return FakeAsync().run((async) {
+        final ticks = <int>[];
+        Timer.periodic(
+            elapseBy,
+            expectAsync1((timer) {
+              ticks.add(timer.tick);
+            }, count: 2));
+        async
+          ..elapse(elapseBy)
+          ..elapse(elapseBy);
+        expect(ticks, [1, 2]);
+      });
+    });
+
+    test('should update periodic timer state before invoking callback', () {
+      // Regression test for: https://github.com/dart-lang/fake_async/issues/88
+      FakeAsync().run((async) {
+        final log = <String>[];
+        Timer.periodic(const Duration(seconds: 2), (timer) {
+          log.add('periodic ${timer.tick}');
+          async.elapse(Duration.zero);
+        });
+        Timer(const Duration(seconds: 3), () {
+          log.add('single');
+        });
+
+        async.flushTimers(flushPeriodicTimers: false);
+        expect(log, ['periodic 1', 'single']);
+      });
+    });
+  });
+
+  group('clock', () {
+    test('updates following elapse()', () {
+      FakeAsync().run((async) {
+        final before = clock.now();
+        async.elapse(elapseBy);
+        expect(clock.now(), before.add(elapseBy));
+      });
+    });
+
+    test('updates following elapseBlocking()', () {
+      FakeAsync().run((async) {
+        final before = clock.now();
+        async.elapseBlocking(elapseBy);
+        expect(clock.now(), before.add(elapseBy));
+      });
+    });
+
+    group('starts at', () {
+      test('the time at which the FakeAsync was created', () {
+        final start = DateTime.now();
+        FakeAsync().run((async) {
+          expect(clock.now(), _closeToTime(start));
+          async.elapse(elapseBy);
+          expect(clock.now(), _closeToTime(start.add(elapseBy)));
+        });
+      });
+
+      test('the value of clock.now()', () {
+        final start = DateTime(1990, 8, 11);
+        withClock(Clock.fixed(start), () {
+          FakeAsync().run((async) {
+            expect(clock.now(), start);
+            async.elapse(elapseBy);
+            expect(clock.now(), start.add(elapseBy));
+          });
+        });
+      });
+
+      test('an explicit value', () {
+        final start = DateTime(1990, 8, 11);
+        FakeAsync(initialTime: start).run((async) {
+          expect(clock.now(), start);
+          async.elapse(elapseBy);
+          expect(clock.now(), start.add(elapseBy));
+        });
+      });
+    });
+  });
+}
+
+/// Returns a matcher that asserts that a [DateTime] is within 100ms of
+/// [expected].
+Matcher _closeToTime(DateTime expected) => predicate(
+    (actual) =>
+        expected.difference(actual as DateTime).inMilliseconds.abs() < 100,
+    'is close to $expected');