Test service extensions (#7849)

...and fix bugs that the tests uncovered.

WRITE TEST FIND BUG

dev/automated_tests/flutter_test/test_async_utils_guarded_test.dart

@@ -2,9 +2,16 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 
+class TestTestBinding extends AutomatedTestWidgetsFlutterBinding {
+  @override
+  DebugPrintCallback get debugPrintOverride => testPrint;
+  static void testPrint(String message, { int wrapWidth }) { print(message); }
+}
+
 Future<Null> guardedHelper(WidgetTester tester) {
   return TestAsyncUtils.guard(() async {
     await tester.pumpWidget(new Text('Hello'));
@@ -12,8 +19,8 @@ Future<Null> guardedHelper(WidgetTester tester) {
 }
 
 void main() {
+  new TestTestBinding();
   testWidgets('TestAsyncUtils - custom guarded sections', (WidgetTester tester) async {
-    debugPrint = (String message, { int wrapWidth }) { print(message); };
     await tester.pumpWidget(new Container());
     expect(find.byElementType(Container), isNotNull);
     guardedHelper(tester);

dev/automated_tests/flutter_test/test_async_utils_unguarded_test.dart

@@ -2,16 +2,22 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/widgets.dart';
+import 'package:flutter/foundation.dart';
 import 'package:flutter_test/flutter_test.dart';
 
+class TestTestBinding extends AutomatedTestWidgetsFlutterBinding {
+  @override
+  DebugPrintCallback get debugPrintOverride => testPrint;
+  static void testPrint(String message, { int wrapWidth }) { print(message); }
+}
+
 Future<Null> helperFunction(WidgetTester tester) async {
   await tester.pump();
 }
 
 void main() {
+  new TestTestBinding();
   testWidgets('TestAsyncUtils - handling unguarded async helper functions', (WidgetTester tester) async {
-    debugPrint = (String message, { int wrapWidth }) { print(message); };
     helperFunction(tester);
     helperFunction(tester);
     // this should fail

examples/flutter_gallery/test/example_code_parser_test.dart

@@ -46,7 +46,7 @@ class TestAssetBundle extends AssetBundle {
   }
 
   @override
-  Future<dynamic> loadStructuredData<T>(String key, Future<T> parser(String value)) async {
+  Future<T> loadStructuredData<T>(String key, Future<T> parser(String value)) async {
     return parser(await loadString(key));
   }
 

packages/flutter/lib/foundation.dart

@@ -13,6 +13,7 @@ export 'src/foundation/assertions.dart';
 export 'src/foundation/basic_types.dart';
 export 'src/foundation/binding.dart';
 export 'src/foundation/change_notifier.dart';
+export 'src/foundation/debug.dart';
 export 'src/foundation/licenses.dart';
 export 'src/foundation/observer_list.dart';
 export 'src/foundation/platform.dart';

packages/flutter/lib/src/foundation/binding.dart

@@ -19,7 +19,7 @@ import 'basic_types.dart';
 /// "type" key will be set to the string `_extensionType` to indicate
 /// that this is a return value from a service extension, and the
 /// "method" key will be set to the full name of the method.
-typedef Future<Map<String, dynamic>> ServiceExtensionCallback(Map<String, String> parameters);
+typedef Future<Map<String, String>> ServiceExtensionCallback(Map<String, String> parameters);
 
 /// Base class for mixins that provide singleton services (also known as
 /// "bindings").
@@ -56,7 +56,7 @@ abstract class BindingBase {
     initServiceExtensions();
     assert(_debugServiceExtensionsRegistered);
 
-    developer.postEvent('Flutter.FrameworkInitialization', <String, dynamic>{});
+    developer.postEvent('Flutter.FrameworkInitialization', <String, String>{});
 
     developer.Timeline.finishSync();
   }
@@ -150,7 +150,7 @@ abstract class BindingBase {
       name: name,
       callback: (Map<String, String> parameters) async {
         await callback();
-        return <String, dynamic>{};
+        return <String, String>{};
       }
     );
   }
@@ -181,7 +181,7 @@ abstract class BindingBase {
       callback: (Map<String, String> parameters) async {
         if (parameters.containsKey('enabled'))
           await setter(parameters['enabled'] == 'true');
-        return <String, dynamic>{ 'enabled': await getter() };
+        return <String, String>{ 'enabled': await getter() ? 'true' : 'false' };
       }
     );
   }
@@ -211,7 +211,7 @@ abstract class BindingBase {
       callback: (Map<String, String> parameters) async {
         if (parameters.containsKey(name))
           await setter(double.parse(parameters[name]));
-        return <String, dynamic>{ name: await getter() };
+        return <String, String>{ name: (await getter()).toString() };
       }
     );
   }
@@ -240,7 +240,7 @@ abstract class BindingBase {
       callback: (Map<String, String> parameters) async {
         if (parameters.containsKey('value'))
           await setter(parameters['value']);
-        return <String, dynamic>{ 'value': await getter() };
+        return <String, String>{ 'value': await getter() };
       }
     );
   }
@@ -267,7 +267,7 @@ abstract class BindingBase {
       assert(method == methodName);
       dynamic caughtException;
       StackTrace caughtStack;
-      Map<String, dynamic> result;
+      Map<String, String> result;
       try {
         result = await callback(parameters);
       } catch (exception, stack) {
@@ -286,10 +286,10 @@ abstract class BindingBase {
         ));
         return new developer.ServiceExtensionResponse.error(
           developer.ServiceExtensionResponse.extensionError,
-          JSON.encode(<String, dynamic>{
+          JSON.encode(<String, String>{
             'exception': caughtException.toString(),
             'stack': caughtStack.toString(),
-            'method': method
+            'method': method,
           })
         );
       }

packages/flutter/lib/src/foundation/debug.dart

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'assertions.dart';
+import 'print.dart';
+
+/// Returns true if none of the foundation library debug variables have been
+/// changed.
+///
+/// This function is used by the test framework to ensure that debug variables
+/// haven't been inadvertently changed.
+///
+/// The `debugPrintOverride` argument can be specified to indicate the expected
+/// value of the [debugPrint] variable. This is useful for test frameworks that
+/// override [debugPrint] themselves and want to check that their own custom
+/// value wasn't overridden by a test.
+///
+/// See [https://docs.flutter.io/flutter/foundation/foundation-library.html] for
+/// a complete list.
+bool debugAssertAllFoundationVarsUnset(String reason, { DebugPrintCallback debugPrintOverride: debugPrintThrottled }) {
+  assert(() {
+    if (debugPrint != debugPrintOverride)
+      throw new FlutterError(reason);
+    return true;
+  });
+  return true;
+}

packages/flutter/lib/src/rendering/binding.dart

@@ -57,8 +57,7 @@ abstract class RendererBinding extends BindingBase implements SchedulerBinding,
           if (debugPaintSizeEnabled == value)
             return new Future<Null>.value();
           debugPaintSizeEnabled = value;
-          _forceRepaint();
-          return endOfFrame;
+          return _forceRepaint();
         }
       );
       return true;
@@ -78,8 +77,8 @@ abstract class RendererBinding extends BindingBase implements SchedulerBinding,
           bool repaint = debugRepaintRainbowEnabled && !value;
           debugRepaintRainbowEnabled = value;
           if (repaint)
-            _forceRepaint();
-          return endOfFrame;
+            return _forceRepaint();
+          return new Future<Null>.value();
         }
       );
       return true;
@@ -249,13 +248,14 @@ abstract class RendererBinding extends BindingBase implements SchedulerBinding,
     super.hitTest(result, position); // ignore: abstract_super_member_reference
   }
 
-  void _forceRepaint() {
+  Future<Null> _forceRepaint() {
     RenderObjectVisitor visitor;
     visitor = (RenderObject child) {
       child.markNeedsPaint();
       child.visitChildren(visitor);
     };
     instance?.renderView?.visitChildren(visitor);
+    return endOfFrame;
   }
 }
 

packages/flutter/lib/src/services/asset_bundle.dart

@@ -66,7 +66,7 @@ abstract class AssetBundle {
   ///
   /// Implementations may cache the result, so a particular key should only be
   /// used with one parser for the lifetime of the asset bundle.
-  Future<dynamic> loadStructuredData<T>(String key, Future<T> parser(String value));
+  Future<T> loadStructuredData<T>(String key, Future<T> parser(String value));
 
   /// If this is a caching asset bundle, and the given key describes a cached
   /// asset, then evict the asset from the cache so that the next time it is
@@ -110,7 +110,7 @@ class NetworkAssetBundle extends AssetBundle {
   /// The result is not cached. The parser is run each time the resource is
   /// fetched.
   @override
-  Future<dynamic> loadStructuredData<T>(String key, Future<T> parser(String value)) async {
+  Future<T> loadStructuredData<T>(String key, Future<T> parser(String value)) async {
     assert(key != null);
     assert(parser != null);
     return parser(await loadString(key));
@@ -159,7 +159,7 @@ abstract class CachingAssetBundle extends AssetBundle {
   /// subsequent calls will be a [SynchronousFuture], which resolves its
   /// callback synchronously.
   @override
-  Future<dynamic> loadStructuredData<T>(String key, Future<T> parser(String value)) {
+  Future<T> loadStructuredData<T>(String key, Future<T> parser(String value)) {
     assert(key != null);
     assert(parser != null);
     if (_structuredDataCache.containsKey(key))

packages/flutter/lib/src/widgets/binding.dart

@@ -86,8 +86,7 @@ abstract class WidgetsBinding extends BindingBase implements GestureBinding, Ren
         if (WidgetsApp.showPerformanceOverlayOverride == value)
           return new Future<Null>.value();
         WidgetsApp.showPerformanceOverlayOverride = value;
-        buildOwner.reassemble(renderViewElement);
-        return endOfFrame;
+        return _forceRebuild();
       }
     );
 
@@ -98,12 +97,19 @@ abstract class WidgetsBinding extends BindingBase implements GestureBinding, Ren
         if (WidgetsApp.debugAllowBannerOverride == value)
           return new Future<Null>.value();
         WidgetsApp.debugAllowBannerOverride = value;
-        buildOwner.reassemble(renderViewElement);
-        return endOfFrame;
+        return _forceRebuild();
       }
     );
   }
 
+  Future<Null> _forceRebuild() {
+    if (renderViewElement != null) {
+      buildOwner.reassemble(renderViewElement);
+      return endOfFrame;
+    }
+    return new Future<Null>.value();
+  }
+
   /// The [BuildOwner] in charge of executing the build pipeline for the
   /// widget tree rooted at this binding.
   BuildOwner get buildOwner => _buildOwner;

packages/flutter_test/lib/src/binding.dart

@@ -86,6 +86,14 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
        RendererBinding,
        // Services binding omitted to avoid dragging in the licenses code.
        WidgetsBinding {
+
+  TestWidgetsFlutterBinding() {
+    debugPrint = debugPrintOverride;
+  }
+
+  @protected
+  DebugPrintCallback get debugPrintOverride => debugPrint;
+
   /// Creates and initializes the binding. This function is
   /// idempotent; calling it a second time will just return the
   /// previously-created instance.
@@ -399,6 +407,10 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
     assert(debugAssertNoTransientCallbacks(
       'An animation is still running even after the widget tree was disposed.'
     ));
+    assert(debugAssertAllFoundationVarsUnset(
+      'The value of a foundation debug variable was changed by the test.',
+      debugPrintOverride: debugPrintOverride,
+    ));
     assert(debugAssertAllRenderVarsUnset(
       'The value of a rendering debug variable was changed by the test.'
     ));
@@ -431,7 +443,6 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
 class AutomatedTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
   @override
   void initInstances() {
-    debugPrint = debugPrintSynchronously;
     super.initInstances();
     ui.window.onBeginFrame = null;
   }
@@ -439,6 +450,9 @@ class AutomatedTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
   FakeAsync _fakeAsync;
   Clock _clock;
 
+  @override
+  DebugPrintCallback get debugPrintOverride => debugPrintSynchronously;
+
   @override
   test_package.Timeout get defaultTestTimeout => const test_package.Timeout(const Duration(seconds: 5));
 

packages/flutter_tools/test/test_test.dart

@@ -82,7 +82,7 @@ Future<Null> _testFile(String testName, int wantedExitCode, String workingDirect
       expect(haveSeenStdErrMarker, isFalse);
       haveSeenStdErrMarker = true;
     }
-    expect(outputLine, matches(expectationLine));
+    expect(outputLine, matches(expectationLine), verbose: true, reason: 'Full output:\n- - - -----8<----- - - -\n${output.join("\n")}\n- - - -----8<----- - - -');
     expectationLineNumber += 1;
     outputLineNumber += 1;
   }