Shard firebase_test_lab_tests (#56594)

.cirrus.yml

 # CIRRUS CONFIGURATION FILE
 # https://cirrus-ci.org/guide/writing-tasks/
 
+# YAML anchors used to share fields between tasks.
+# See https://confluence.atlassian.com/bitbucket/yaml-anchors-960154027.html
 web_shard_template: &WEB_SHARD_TEMPLATE
   only_if: "changesInclude('.cirrus.yml', 'dev/**', 'packages/flutter/**', 'packages/flutter_test/**', 'packages/flutter_tools/lib/src/test/**', 'packages/flutter_web_plugins/**', 'bin/internal/**') || $CIRRUS_PR == ''"
   environment:
@@ -32,6 +34,18 @@ macos_shard_template: &MACOS_SHARD_TEMPLATE
     - ulimit -S -n 2048 # https://github.com/flutter/flutter/issues/2976
     - dart --enable-asserts ./dev/bots/test.dart
 
+firebase_shard_template: &FIREBASE_SHARD_TEMPLATE
+  environment:
+    # Empirically, this shard runs in 20-25 minutes with just one CPU and 4G of RAM, as of
+    # October 2019. It does not seem to be sensitive to the number of CPUs or amount of RAM;
+    # doubling CPUs had no effect (mere seconds under 20 minutes), increasing RAM to 24G left it
+    # on the high end of the 20-25 minute range. (This makes sense, as it's just driving the
+    # Firebase test lab remotely.) Less than 4G of RAM made it go OOM.
+    CLOUDSDK_CORE_DISABLE_PROMPTS: 1
+    GCLOUD_FIREBASE_TESTLAB_KEY: ENCRYPTED[1c140257edc48f5578fa5a0e5038b84c8e53270c405efa5a8e35ea303a4e0d135853989f448f72136206de854d17fbec]
+  script:
+    - dart --enable-asserts ./dev/bots/test.dart
+
 use_compute_credits: $CIRRUS_USER_COLLABORATOR == 'true'
 
 environment:
@@ -268,17 +282,15 @@ task:
         - git clone https://github.com/flutter/tests.git bin/cache/pkg/tests
         - dart --enable-asserts dev/customer_testing/run_tests.dart --skip-on-fetch-failure --skip-template bin/cache/pkg/tests/registry/*.test
 
-    - name: firebase_test_lab_tests-linux # linux-only
-      environment:
-        # Empirically, this shard runs in 20-25 minutes with just one CPU and 4G of RAM, as of
-        # October 2019. It does not seem to be sensitive to the number of CPUs or amount of RAM;
-        # doubling CPUs had no effect (mere seconds under 20 minutes), increasing RAM to 24G left it
-        # on the high end of the 20-25 minute range. (This makes sense, as it's just driving the
-        # Firebase test lab remotely.) Less than 4G of RAM made it go OOM.
-        CLOUDSDK_CORE_DISABLE_PROMPTS: 1
-        GCLOUD_FIREBASE_TESTLAB_KEY: ENCRYPTED[1c140257edc48f5578fa5a0e5038b84c8e53270c405efa5a8e35ea303a4e0d135853989f448f72136206de854d17fbec]
-      script:
-        - ./dev/bots/firebase_testlab.sh
+    # firebase_test_lab_tests are linux-only
+    - name: firebase_test_lab_tests-0-linux
+      <<: *FIREBASE_SHARD_TEMPLATE
+
+    - name: firebase_test_lab_tests-1-linux
+      <<: *FIREBASE_SHARD_TEMPLATE
+
+    - name: firebase_test_lab_tests-2-linux
+      <<: *FIREBASE_SHARD_TEMPLATE
 
     - name: web_smoke_test
       only_if: "changesInclude('.cirrus.yml', 'examples/hello_world/**' ,'dev/**', 'packages/flutter/**', 'packages/flutter_test/**', 'packages/flutter_tools/lib/src/test/**', 'packages/flutter_web_plugins/**', 'bin/internal/**') || $CIRRUS_PR == ''"

dev/bots/firebase_testlab.sh

@@ -8,11 +8,8 @@
 # that the app doesn't crash upon startup.
 #
 # When adding a test, ensure that there's at least a `print()` statement under lib/*.dart.
-tests=(
-  "dev/integration_tests/release_smoke_test"
-  "dev/integration_tests/abstract_method_smoke_test"
-  "dev/integration_tests/android_embedding_v2_smoke_test"
-)
+#
+# The first and only parameter should be the path to an integration test.
 
 # The devices where the tests are run.
 #
@@ -79,6 +76,4 @@ function test_app_bundle() {
   popd
 }
 
-for test in ${tests[*]}; do
-  test_app_bundle $test
-done
+test_app_bundle "$1"

dev/bots/test.dart

@@ -118,6 +118,7 @@ Future<void> main(List<String> args) async {
       'add_to_app_tests': _runAddToAppTests,
       'add_to_app_life_cycle_tests': _runAddToAppLifeCycleTests,
       'build_tests': _runBuildTests,
+      'firebase_test_lab_tests': _runFirebaseTestLabTests,
       'framework_coverage': _runFrameworkCoverage,
       'framework_tests': _runFrameworkTests,
       'hostonly_devicelab_tests': _runHostOnlyDeviceLabTests,
@@ -634,6 +635,34 @@ Future<void> _runFrameworkTests() async {
   });
 }
 
+Future<void> _runFirebaseTestLabTests() async {
+  // Firebase Lab tests take ~20 minutes per integration test,
+  // so only one test is run per shard. Therefore, there are as
+  // many shards available as there are integration tests in this list.
+  // If you add a new test, add a corresponding firebase_test_lab-#-linux
+  // to .cirrus.yml
+  final List<String> integrationTests = <String>[
+    'release_smoke_test',
+    'abstract_method_smoke_test',
+    'android_embedding_v2_smoke_test',
+  ];
+  final Map<String, ShardRunner> subshards = <String, ShardRunner>{};
+
+  final String firebaseScript = path.join(flutterRoot, 'dev', 'bots', 'firebase_testlab.sh');
+  final String integrationTestDirectory = path.join(flutterRoot, 'dev', 'integration_tests');
+
+  for (int index = 0; index < integrationTests.length; index += 1) {
+    final String integrationTestPath = path.join(integrationTestDirectory, integrationTests[index]);
+    subshards['$index'] = () => runCommand(
+      firebaseScript,
+      <String>[ integrationTestPath ],
+      workingDirectory: flutterRoot,
+    );
+  }
+
+  await selectSubshard(subshards);
+}
+
 Future<void> _runFrameworkCoverage() async {
   final File coverageFile = File(path.join(flutterRoot, 'packages', 'flutter', 'coverage', 'lcov.info'));
   if (!coverageFile.existsSync()) {