diff --git a/packages/flutter_driver/test/flutter_driver_test.dart b/packages/flutter_driver/test/flutter_driver_test.dart
index 9e2eb40b20b..dcb08dad415 100644
--- a/packages/flutter_driver/test/flutter_driver_test.dart
+++ b/packages/flutter_driver/test/flutter_driver_test.dart
@@ -29,7 +29,7 @@ void main() {
     void expectLogContains(String message) {
       expect(log.map((LogRecord r) => '$r'), anyElement(contains(message)));
     }
-
+    
     setUp(() {
       log = <LogRecord>[];
       logSub = flutterDriverLog.listen(log.add);
@@ -37,9 +37,9 @@ void main() {
       mockVM = new MockVM();
       mockIsolate = new MockIsolate();
       mockPeer = new MockPeer();
-      when(mockClient.getVM()).thenAnswer((_) => new Future<MockVM>.value(mockVM));
+      when(mockClient.getVM()).thenReturn(new Future<MockVM>.value(mockVM));
       when(mockVM.isolates).thenReturn(<VMRunnableIsolate>[mockIsolate]);
-      when(mockIsolate.loadRunnable()).thenAnswer((_) => new Future<MockIsolate>.value(mockIsolate));
+      when(mockIsolate.loadRunnable()).thenReturn(new Future<MockIsolate>.value(mockIsolate));
       when(mockIsolate.invokeExtension(typed(any), typed(any))).thenAnswer(
           (Invocation invocation) => makeMockResponse(<String, dynamic>{'status': 'ok'}));
       vmServiceConnectFunction = (String url) {
diff --git a/packages/fuchsia_remote_debug_protocol/test/fuchsia_remote_connection_test.dart b/packages/fuchsia_remote_debug_protocol/test/fuchsia_remote_connection_test.dart
index b3f9cd79a98..df85bc2ec1a 100644
--- a/packages/fuchsia_remote_debug_protocol/test/fuchsia_remote_connection_test.dart
+++ b/packages/fuchsia_remote_debug_protocol/test/fuchsia_remote_connection_test.dart
@@ -31,7 +31,7 @@ void main() {
       const String interface = 'eno1';
       // Adds some extra junk to make sure the strings will be cleaned up.
       when(mockRunner.run(typed(any)))
-      .thenAnswer((_) => new Future<List<String>>.value(
+      .thenReturn(new Future<List<String>>.value(
           <String>['123\n\n\n', '456  ', '789']));
       when(mockRunner.address).thenReturn(address);
       when(mockRunner.interface).thenReturn(interface);
diff --git a/packages/fuchsia_remote_debug_protocol/test/src/runners/ssh_command_runner_test.dart b/packages/fuchsia_remote_debug_protocol/test/src/runners/ssh_command_runner_test.dart
index 6488018434d..83f7fbc56b5 100644
--- a/packages/fuchsia_remote_debug_protocol/test/src/runners/ssh_command_runner_test.dart
+++ b/packages/fuchsia_remote_debug_protocol/test/src/runners/ssh_command_runner_test.dart
@@ -40,8 +40,8 @@ void main() {
     setUp(() {
       mockProcessManager = new MockProcessManager();
       mockProcessResult = new MockProcessResult();
-      when(mockProcessManager.run(typed(any))).thenAnswer(
-          (_) => new Future<MockProcessResult>.value(mockProcessResult));
+      when(mockProcessManager.run(typed(any))).thenReturn(
+          new Future<MockProcessResult>.value(mockProcessResult));
     });
 
     test('verify interface is appended to ipv6 address', () async {