Merge pull request #2126 from yjbanov/sample-driver-test-waits

wait for text to change in the sample driver test

packages/flutter_driver/lib/src/retry.dart

@@ -19,7 +19,7 @@ Future<dynamic> retry(Action action, Duration timeout,
   assert(timeout != null);
   assert(pauseBetweenRetries != null);
 
-  Stopwatch sw = new Stopwatch()..start();
+  Stopwatch sw = stopwatchFactory()..start();
   dynamic result = null;
   dynamic lastError = null;
   dynamic lastStackTrace = null;
@@ -43,3 +43,14 @@ Future<dynamic> retry(Action action, Duration timeout,
   else
     return new Future.error(lastError, lastStackTrace);
 }
+
+/// A function that produces a [Stopwatch].
+typedef Stopwatch StopwatchFactory();
+
+/// Restores [stopwatchFactory] to the default implementation.
+void restoreStopwatchFactory() {
+  stopwatchFactory = () => new Stopwatch();
+}
+
+/// Used by [retry] as a source of [Stopwatch] implementation.
+StopwatchFactory stopwatchFactory = () => new Stopwatch();

packages/flutter_driver/test/retry_test.dart

@@ -3,14 +3,29 @@
 // found in the LICENSE file.
 
 import 'package:test/test.dart';
+import 'package:quiver/time.dart';
 import 'package:quiver/testing/async.dart';
+import 'package:quiver/testing/time.dart';
 
 import 'package:flutter_driver/src/retry.dart';
 
 main() {
   group('retry', () {
+    FakeAsync fakeAsync;
+
+    setUp(() {
+      fakeAsync = new FakeAsync();
+      Clock fakeClock = fakeAsync.getClock(new DateTime.now());
+      stopwatchFactory = () {
+        return new FakeStopwatch(
+          () => fakeClock.now().millisecondsSinceEpoch,
+          1000
+        );
+      };
+    });
+
     test('retries until succeeds', () {
-      new FakeAsync().run((FakeAsync fakeAsync) {
+      fakeAsync.run((_) {
         int retryCount = 0;
 
         expect(
@@ -37,17 +52,18 @@ main() {
     });
 
     test('times out returning last error', () async {
+      fakeAsync.run((_) {
         bool timedOut = false;
         int retryCount = 0;
         dynamic lastError;
         dynamic lastStackTrace;
 
-      await retry(
+        retry(
           () {
             retryCount++;
             throw 'error';
           },
-        new Duration(milliseconds: 9),
+          new Duration(milliseconds: 7),
           new Duration(milliseconds: 2)
         ).catchError((error, stackTrace) {
           timedOut = true;
@@ -55,10 +71,15 @@ main() {
           lastStackTrace = stackTrace;
         });
 
+        print('before elapse');
+        fakeAsync.elapse(new Duration(milliseconds: 10));
+        print('after elapse');
+
         expect(timedOut, isTrue);
         expect(lastError, 'error');
         expect(lastStackTrace, isNotNull);
         expect(retryCount, 4);
-    }, skip: "Flaky. See https://github.com/flutter/flutter/issues/2133");
+      });
+    });
   });
 }

packages/flutter_tools/templates/driver/e2e_test.dart.tmpl

@@ -32,13 +32,18 @@ main() {
     });
 
     test('tap on the floating action button; verify counter', () async {
+      // Find floating action button (fab) to tap on
       ObjectRef fab = await driver.findByValueKey('fab');
       expect(fab, isNotNull);
+
+      // Tap on the fab
       await driver.tap(fab);
+
+      // Wait for text to change to the desired value
+      await driver.waitFor(() async {
         ObjectRef counter = await driver.findByValueKey('counter');
-      expect(counter, isNotNull);
-      String text = await driver.getText(counter);
-      expect(text, contains("Button tapped 1 times."));
+        return await driver.getText(counter);
+      }, contains("Button tapped 1 times."));
     });
   });
 }