Tree Build Status changes the AppBar color

app_flutter/lib/main.dart

@@ -40,9 +40,12 @@ class _BuildDashboardPageState extends State<BuildDashboardPage> {
 
   @override
   Widget build(BuildContext context) {
+    final ThemeData theme = Theme.of(context);
     return Scaffold(
       appBar: AppBar(
         title: Text('Flutter Build Dashboard v2'),
+        backgroundColor:
+            buildState.isTreeBuilding ? theme.primaryColor : theme.errorColor,
       ),
       body: Column(
         children: [

app_flutter/lib/service/appengine_cocoon.dart

@@ -46,6 +46,48 @@ class AppEngineCocoonService implements CocoonService {
     return _commitStatusesFromJson(jsonResponse['Statuses']);
   }
 
+  @override
+  Future<bool> fetchTreeBuildStatus() async {
+    /// This endpoint returns JSON {AnticipatedBuildStatus: [BuildStatus]}
+    http.Response response =
+        await _client.get('$_baseApiUrl/public/build-status');
+
+    if (response.statusCode != HttpStatus.ok) {
+      throw HttpException(
+          '$_baseApiUrl/public/build-status returned ${response.statusCode}');
+    }
+
+    Map<String, Object> jsonResponse = jsonDecode(response.body);
+
+    if (!_isBuildStatusResponseValid(jsonResponse)) {
+      throw HttpException(
+          '$_baseApiUrl/public/build-status had a malformed response');
+    }
+
+    return jsonResponse['AnticipatedBuildStatus'] == "Succeeded";
+  }
+
+  /// Check if [Map<String,Object>] follows the format for build-status.
+  ///
+  /// Template of the response it should receive:
+  /// ```json
+  /// {
+  ///   "AnticipatedBuildStatus": "Succeeded"|"Failed"
+  /// }
+  /// ```
+  bool _isBuildStatusResponseValid(Map<String, Object> response) {
+    if (!response.containsKey('AnticipatedBuildStatus')) {
+      return false;
+    }
+
+    String treeBuildStatus = response['AnticipatedBuildStatus'];
+    if (treeBuildStatus != 'Failed' && treeBuildStatus != 'Succeeded') {
+      return false;
+    }
+
+    return true;
+  }
+
   List<CommitStatus> _commitStatusesFromJson(List<Object> jsonCommitStatuses) {
     assert(jsonCommitStatuses != null);
     // TODO(chillers): Remove adapter code to just use proto fromJson method. https://github.com/flutter/cocoon/issues/441

app_flutter/lib/service/cocoon.dart

@@ -31,4 +31,7 @@ abstract class CocoonService {
   ///
   /// TODO(chillers): Make configurable to get range of commits
   Future<List<CommitStatus>> fetchCommitStatuses();
+
+  /// Gets the current build status of flutter/flutter.
+  Future<bool> fetchTreeBuildStatus();
 }

app_flutter/lib/service/fake_cocoon.dart

@@ -18,6 +18,11 @@ class FakeCocoonService implements CocoonService {
     return Future.value(_createFakeCommitStatuses());
   }
 
+  @override
+  Future<bool> fetchTreeBuildStatus() async {
+    return true;
+  }
+
   List<CommitStatus> _createFakeCommitStatuses() {
     List<CommitStatus> stats = <CommitStatus>[];
 

app_flutter/lib/state/flutter_build.dart

@@ -26,6 +26,10 @@ class FlutterBuildState extends ChangeNotifier {
   /// The current status of the commits loaded.
   List<CommitStatus> statuses = [];
 
+  /// Whether or not flutter/flutter currently passes tests.
+  bool get isTreeBuilding => _isTreeBuilding;
+  bool _isTreeBuilding = true;
+
   /// Creates a new [FlutterBuildState].
   ///
   /// If [CocoonService] is not specified, a new [CocoonService] instance is created.
@@ -39,13 +43,24 @@ class FlutterBuildState extends ChangeNotifier {
       return;
     }
 
+    /// [Timer.periodic] does not necessarily run at the start of the timer.
+    _fetchBuildStatusUpdate();
+
     refreshTimer =
         Timer.periodic(refreshRate, (t) => _fetchBuildStatusUpdate());
   }
 
   /// Request the latest [statuses] from [CocoonService].
   void _fetchBuildStatusUpdate() async {
-    statuses = await _cocoonService.fetchCommitStatuses();
+    await Future.wait([
+      _cocoonService
+          .fetchCommitStatuses()
+          .then((commitStatuses) => statuses = commitStatuses),
+      _cocoonService
+          .fetchTreeBuildStatus()
+          .then((treeStatus) => _isTreeBuilding = treeStatus),
+    ]);
+
     notifyListeners();
   }
 

app_flutter/test/service/appengine_cocoon_test.dart

@@ -63,8 +63,20 @@ const String jsonGetStatsResponse = """
       }
 """;
 
+const String jsonBuildStatusTrueResponse = """
+  {
+    "AnticipatedBuildStatus": "Succeeded"
+  }
+""";
+
+const String jsonBuildStatusFalseResponse = """
+  {
+    "AnticipatedBuildStatus": "Failed"
+  }
+""";
+
 void main() {
-  group('AppEngine CocoonService', () {
+  group('AppEngine CocoonService fetchCommitStatus ', () {
     AppEngineCocoonService service;
 
     setUp(() async {
@@ -123,4 +135,48 @@ void main() {
       expect(service.fetchCommitStatuses(), throwsException);
     });
   });
+
+  group('AppEngine CocoonService fetchTreeBuildStatus ', () {
+    AppEngineCocoonService service;
+
+    setUp(() async {
+      service = AppEngineCocoonService(client: MockClient((request) async {
+        return Response(jsonBuildStatusTrueResponse, 200);
+      }));
+    });
+
+    test('should return bool', () {
+      expect(service.fetchTreeBuildStatus(), TypeMatcher<Future<bool>>());
+    });
+
+    test('should return true when given Succeeded', () async {
+      bool treeBuildStatus = await service.fetchTreeBuildStatus();
+
+      expect(treeBuildStatus, true);
+    });
+
+    test('should return false when given Failed', () async {
+      service = AppEngineCocoonService(client: MockClient((request) async {
+        return Response(jsonBuildStatusFalseResponse, 200);
+      }));
+
+      bool treeBuildStatus = await service.fetchTreeBuildStatus();
+
+      expect(treeBuildStatus, false);
+    });
+
+    test('should throw exception if given non-200 response', () {
+      service = AppEngineCocoonService(
+          client: MockClient((request) async => Response('', 404)));
+
+      expect(service.fetchTreeBuildStatus(), throwsException);
+    });
+
+    test('should throw exception if given bad response', () {
+      service = AppEngineCocoonService(
+          client: MockClient((request) async => Response('bad', 200)));
+
+      expect(service.fetchTreeBuildStatus(), throwsException);
+    });
+  });
 }

app_flutter/test/state/flutter_build_test.dart

@@ -18,27 +18,31 @@ void main() {
     setUp(() {
       mockService = MockCocoonService();
       buildState = FlutterBuildState(cocoonService: mockService);
+
+      when(mockService.fetchCommitStatuses())
+          .thenAnswer((_) => Future.value([]));
+      when(mockService.fetchTreeBuildStatus())
+          .thenAnswer((_) => Future.value(true));
     });
 
     testWidgets('timer should periodically fetch updates',
         (WidgetTester tester) async {
       buildState.startFetchingBuildStateUpdates();
-      verifyZeroInteractions(mockService);
+
+      // startFetching immediately starts fetching results
+      verify(mockService.fetchCommitStatuses()).called(1);
 
       // Periodic timers don't necessarily run at the same time in each interval.
       // We double the refreshRate to gurantee a call would have been made.
       await tester.pump(buildState.refreshRate * 2);
-      verify(mockService.fetchCommitStatuses()).called(greaterThan(0));
-
-      await tester.pump(buildState.refreshRate * 2);
-      // Now we check to see if another call had been made
       verify(mockService.fetchCommitStatuses()).called(greaterThan(1));
 
       // Tear down fails to cancel the timer before the test is over
       buildState.dispose();
     });
 
-    test('multiple start updates should not change the timer', () {
+    testWidgets('multiple start updates should not change the timer',
+        (WidgetTester tester) async {
       buildState.startFetchingBuildStateUpdates();
       Timer refreshTimer = buildState.refreshTimer;
 
@@ -47,6 +51,10 @@ void main() {
 
       expect(refreshTimer, equals(buildState.refreshTimer));
 
+      // Since startFetching sends out requests on start, we need to wait
+      // for them to finish before disposing of the state.
+      await tester.pumpAndSettle();
+
       // Tear down fails to cancel the timer before the test is over
       buildState.dispose();
     });