git branch flag (#71886)

dev/devicelab/bin/run.dart

@@ -22,6 +22,9 @@ List<String> _taskNames = <String>[];
 /// The device-id to run test on.
 String deviceId;
 
+/// The git branch being tested on.
+String gitBranch;
+
 /// The build of the local engine to use.
 ///
 /// Required for A/B test mode.
@@ -88,6 +91,7 @@ Future<void> main(List<String> rawArgs) async {
 
   deviceId = args['device-id'] as String;
   exitOnFirstTestFailure = args['exit'] as bool;
+  gitBranch = args['git-branch'] as String;
   localEngine = args['local-engine'] as String;
   localEngineSrcPath = args['local-engine-src-path'] as String;
   luciBuilder = args['luci-builder'] as String;
@@ -119,7 +123,7 @@ Future<void> _runTasks() async {
     if (serviceAccountTokenFile != null) {
       final Cocoon cocoon = Cocoon(serviceAccountTokenPath: serviceAccountTokenFile);
       /// Cocoon references LUCI tasks by the [luciBuilder] instead of [taskName].
-      await cocoon.sendTaskResult(builderName: luciBuilder, result: result);
+      await cocoon.sendTaskResult(builderName: luciBuilder, result: result, gitBranch: gitBranch);
     }
 
     if (!result.succeeded) {
@@ -326,6 +330,11 @@ final ArgParser _argParser = ArgParser()
     defaultsTo: true,
     help: 'Exit on the first test failure.',
   )
+  ..addOption(
+    'git-branch',
+    help: '[Flutter infrastructure] Git branch of the current commit. LUCI\n'
+          'checkouts run in detached HEAD state, so the branch must be passed.',
+  )
   ..addOption(
     'local-engine',
     help: 'Name of a build output within the engine out directory, if you\n'

dev/devicelab/lib/framework/cocoon.dart

@@ -48,9 +48,6 @@ class Cocoon {
 
   static final Logger logger = Logger('CocoonClient');
 
-  String get commitBranch => _commitBranch ?? _readCommitBranch();
-  String _commitBranch;
-
   String get commitSha => _commitSha ?? _readCommitSha();
   String _commitSha;
 
@@ -64,18 +61,12 @@ class Cocoon {
     return _commitSha = result.stdout as String;
   }
 
-  /// Parse the local repo for the current running branch.
-  String _readCommitBranch() {
-    final ProcessResult result = processRunSync('git', <String>['rev-parse', '--abbrev-ref', 'HEAD']);
-    if (result.exitCode != 0) {
-      throw CocoonException(result.stderr as String);
-    }
-
-    return _commitBranch = result.stdout as String;
-  }
-
   /// Send [TaskResult] to Cocoon.
-  Future<void> sendTaskResult({String builderName, TaskResult result}) async {
+  Future<void> sendTaskResult({@required String builderName, @required TaskResult result, @required String gitBranch}) async {
+    assert(builderName != null);
+    assert(gitBranch != null);
+    assert(result != null);
+
     // Skip logging on test runs
     Logger.root.level = Level.ALL;
     Logger.root.onRecord.listen((LogRecord rec) {
@@ -83,7 +74,7 @@ class Cocoon {
     });
 
     final Map<String, dynamic> status = <String, dynamic>{
-      'CommitBranch': commitBranch,
+      'CommitBranch': gitBranch,
       'CommitSha': commitSha,
       'BuilderName': builderName,
       'NewStatus': result.succeeded ? 'Succeeded' : 'Failed',

dev/devicelab/test/cocoon_test.dart

@@ -27,7 +27,6 @@ void main() {
       _processResult;
 
   // Expected test values.
-  const String commitBranch = 'flutter-1.23-candidate.18';
   const String commitSha = 'a4952838bf288a81d8ea11edfd4b4cd649fa94cc';
   const String serviceAccountTokenPath = 'test_account_file';
   const String serviceAccountToken = 'test_token';
@@ -45,18 +44,6 @@ void main() {
       serviceAccountFile.writeAsStringSync(serviceAccountToken);
     });
 
-    test('returns expected commit branch', () {
-      _processResult = ProcessResult(1, 0, commitBranch, '');
-      cocoon = Cocoon(
-        serviceAccountTokenPath: serviceAccountTokenPath,
-        filesystem: fs,
-        httpClient: mockClient,
-        processRunSync: runSyncStub,
-      );
-
-      expect(cocoon.commitBranch, commitBranch);
-    });
-
     test('returns expected commit sha', () {
       _processResult = ProcessResult(1, 0, commitSha, '');
       cocoon = Cocoon(
@@ -78,7 +65,6 @@ void main() {
         processRunSync: runSyncStub,
       );
 
-      expect(() => cocoon.commitBranch, throwsA(isA<CocoonException>()));
       expect(() => cocoon.commitSha, throwsA(isA<CocoonException>()));
     });
 
@@ -93,7 +79,7 @@ void main() {
 
       final TaskResult result = TaskResult.success(<String, dynamic>{});
       // This should not throw an error.
-      await cocoon.sendTaskResult(builderName: 'builderAbc', result: result);
+      await cocoon.sendTaskResult(builderName: 'builderAbc', gitBranch: 'branchAbc', result: result);
     });
 
     test('throws client exception on non-200 responses', () async {
@@ -106,7 +92,20 @@ void main() {
       );
 
       final TaskResult result = TaskResult.success(<String, dynamic>{});
-      expect(() => cocoon.sendTaskResult(builderName: 'builderAbc', result: result), throwsA(isA<ClientException>()));
+      expect(() => cocoon.sendTaskResult(builderName: 'builderAbc', gitBranch: 'branchAbc', result: result), throwsA(isA<ClientException>()));
+    });
+
+    test('null git branch throws error', () async {
+      mockClient = MockClient((Request request) async => Response('', 500));
+
+      cocoon = Cocoon(
+        serviceAccountTokenPath: serviceAccountTokenPath,
+        filesystem: fs,
+        httpClient: mockClient,
+      );
+
+      final TaskResult result = TaskResult.success(<String, dynamic>{});
+      expect(() => cocoon.sendTaskResult(builderName: 'builderAbc', gitBranch: null, result: result), throwsA(isA<AssertionError>()));
     });
   });