Add a timeout to pumpAndSettle. (#9195)

packages/flutter_test/lib/src/binding.dart

@@ -141,6 +141,16 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
   /// The default test timeout for tests when using this binding.
   test_package.Timeout get defaultTestTimeout;
 
+  /// The current time.
+  ///
+  /// In the automated test environment (`flutter test`), this is a fake clock
+  /// that begins in January 2015 at the start of the test and advances each
+  /// time [pump] is called with a non-zero duration.
+  ///
+  /// In the live testing environment (`flutter run`), this object shows the
+  /// actual current wall-clock time.
+  Clock get clock;
+
   /// Triggers a frame sequence (build/layout/paint/etc),
   /// then flushes microtasks.
   ///
@@ -466,6 +476,9 @@ class AutomatedTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
   }
 
   FakeAsync _fakeAsync;
+
+  @override
+  Clock get clock => _clock;
   Clock _clock;
 
   @override
@@ -490,7 +503,7 @@ class AutomatedTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
       _phase = newPhase;
       if (hasScheduledFrame) {
         handleBeginFrame(new Duration(
-          milliseconds: _clock.now().millisecondsSinceEpoch
+          milliseconds: _clock.now().millisecondsSinceEpoch,
         ));
       }
       _fakeAsync.flushMicrotasks();
@@ -615,6 +628,9 @@ class LiveTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
   bool get inTest => _inTest;
   bool _inTest = false;
 
+  @override
+  Clock get clock => const Clock();
+
   @override
   int get microtaskCount {
     // Unsupported until we have a wrapper around the real async API

packages/flutter_test/lib/src/widget_tester.dart

@@ -198,9 +198,13 @@ class WidgetTester extends WidgetController implements HitTestDispatcher, Ticker
   ///
   /// This essentially waits for all animations to have completed.
   ///
-  /// This function will never return (and the test will hang and eventually
-  /// time out and fail) if there is an infinite animation in progress (for
-  /// example, if there is an indeterminate progress indicator spinning).
+  /// If it takes longer that the given `timeout` to settle, then the test will
+  /// fail (this method will throw an exception). In particular, this means that
+  /// if there is an infinite animation in progress (for example, if there is an
+  /// indeterminate progress indicator spinning), this method will throw.
+  ///
+  /// The default timeout is ten minutes, which is longer than most reasonable
+  /// finite animations would last.
   ///
   /// If the function returns, it returns the number of pumps that it performed.
   ///
@@ -213,13 +217,19 @@ class WidgetTester extends WidgetController implements HitTestDispatcher, Ticker
   /// matches the expected number of pumps.
   Future<int> pumpAndSettle([
       Duration duration = const Duration(milliseconds: 100),
-      EnginePhase phase = EnginePhase.sendSemanticsTree
+      EnginePhase phase = EnginePhase.sendSemanticsTree,
+      Duration timeout = const Duration(minutes: 10),
     ]) {
     assert(duration != null);
     assert(duration > Duration.ZERO);
+    assert(timeout != null);
+    assert(timeout > Duration.ZERO);
     int count = 0;
     return TestAsyncUtils.guard(() async {
+      final DateTime endTime = binding.clock.fromNowBy(timeout);
       do {
+        if (binding.clock.now().isAfter(endTime))
+          throw new FlutterError('pumpAndSettle timed out');
         await binding.pump(duration, phase);
         count += 1;
       } while (hasRunningAnimations);

packages/flutter_test/test/widget_tester_test.dart

@@ -201,4 +201,24 @@ void main() {
     await tester.pumpAndSettle();
     expect(tester.hasRunningAnimations, isFalse);
   });
+
+  testWidgets('pumpAndSettle control test', (WidgetTester tester) async {
+    final AnimationController controller = new AnimationController(
+      duration: const Duration(minutes: 525600),
+      vsync: const TestVSync()
+    );
+    expect(await tester.pumpAndSettle(), 1);
+    controller.forward();
+    try {
+      await tester.pumpAndSettle();
+      expect(true, isFalse);
+    } catch (e) {
+      expect(e, isFlutterError);
+    }
+    controller.stop();
+    expect(await tester.pumpAndSettle(), 1);
+    controller.duration = const Duration(seconds: 1);
+    controller.forward();
+    expect(await tester.pumpAndSettle(const Duration(milliseconds: 300)), 5); // 0, 300, 600, 900, 1200ms
+  });
 }