TestWidgetsFlutterBinding class Null safety

Base class for bindings used by widgets library tests.

The ensureInitialized method creates (if necessary) and returns an instance of the appropriate subclass. (If one is already created, it returns that one, even if it's not the one that it would normally create. This allows tests to force the use of LiveTestWidgetsFlutterBinding even in a normal unit test environment, e.g. to test that binding.)

When using these bindings, certain features are disabled. For example, timeDilation is reset to 1.0 on initialization.

In non-browser tests, the binding overrides HttpClient creation with a fake client that always returns a status code of 400. This is to prevent tests from making network calls, which could introduce flakiness. A test that actually needs to make a network call should provide its own HttpClient to the code making the call, so that it can appropriately mock or fake responses.

Coordinate spaces

TestWidgetsFlutterBinding might be run on devices of different screen sizes, while the testing widget is still told the same size to ensure consistent results. Consequently, code that deals with positions (such as pointer events or painting) must distinguish between two coordinate spaces:

The local coordinate space is the one used by the testing widget (typically an 800 by 600 window, but can be altered by setSurfaceSize).
The global coordinate space is the one used by the device.

Positions can be transformed between coordinate spaces with localToGlobal and globalToLocal.

Inheritance

Object
BindingBase
TestWidgetsFlutterBinding

Mixed in types

Implementers

Constructors

TestWidgetsFlutterBinding(): Constructor for TestWidgetsFlutterBinding.

Properties

accessibilityFeatures → AccessibilityFeatures: The currently active set of AccessibilityFeatures.
read-onlyinherited
buildOwner → BuildOwner?: The BuildOwner in charge of executing the build pipeline for the widget tree rooted at this binding.
read-onlyinherited
channelBuffers → ChannelBuffers: The low level buffering and dispatch mechanism for messages sent by plugins on the engine side to their corresponding plugin code on the framework side.
read-onlyinherited
clock → Clock: The current time.
read-only
currentFrameTimeStamp → Duration: The time stamp for the frame currently being processed.
read-onlyinherited
currentSystemFrameTimeStamp → Duration: The raw time stamp as provided by the engine to dart:ui.PlatformDispatcher.onBeginFrame for the frame currently being processed.
read-onlyinherited
debugBuildingDirtyElements ↔ bool: Whether we are currently in a frame. This is used to verify that frames are not scheduled redundantly.
protected">@protectedread / writeinherited
debugDidSendFirstFrameEvent → bool: Whether the first frame has finished building.
read-onlyinherited
debugPrintOverride → DebugPrintCallback: The value to set debugPrint to while tests are running.
read-only
debugSamplingClock → SamplingClock?: Overrides the sampling clock for debugging and testing.
protected">@protectedread-onlyinherited
defaultBinaryMessenger → TestDefaultBinaryMessenger: The default instance of BinaryMessenger.
read-onlyinherited
defaultTestTimeout → Timeout: The default test timeout for tests when using this binding.
read-only
disableAnimations → bool: The platform is requesting that animations be disabled or simplified.
read-onlyinherited
disableShadows → bool: The value to set debugDisableShadows to while tests are running.
protected">@protectedread-only
endOfFrame → Future<void>: Returns a Future that completes after the frame completes.
read-onlyinherited
firstFrameRasterized → bool: Whether the Flutter engine has rasterized the first frame.
read-onlyinherited
focusedEditable ↔ EditableTextState?: The State of the current EditableText client of the onscreen keyboard.
read / write
focusManager → FocusManager: The object in charge of the focus tree.
read-onlyinherited
framesEnabled → bool: Whether frames are currently being scheduled when scheduleFrame is called.
read-onlyinherited
gestureArena → GestureArenaManager: The gesture arenas used for disambiguating the meaning of sequences of pointer events.
finalinherited
hashCode → int: The hash code for this object.
read-onlyinherited
hasScheduledFrame → bool: Whether this scheduler has requested that handleBeginFrame be called soon.
read-onlyinherited
imageCache → ImageCache: The singleton that implements the Flutter framework's image cache.
read-onlyinherited
inTest → bool: Whether there is currently a test executing.
read-only
isRootWidgetAttached → bool: Whether the renderViewElement has been initialized.
read-onlyinherited
keyboard → HardwareKeyboard: The global singleton instance of HardwareKeyboard, which can be used to query keyboard states.
read-onlyinherited
keyEventManager → KeyEventManager: The global singleton instance of KeyEventManager, which is used internally to dispatch key messages.
read-onlyinherited
lifecycleState → AppLifecycleState?: Whether the application is visible, and if so, whether it is currently interactive.
read-onlyinherited
locked → bool: Whether lockEvents is currently locking events.
protected">@protectedread-onlyinherited
microtaskCount → int: The number of outstanding microtasks in the queue.
read-only
mouseTracker → MouseTracker: The object that manages state about currently connected mice, for hover notification.
read-onlyinherited
overrideHttpClient → bool: Determines whether the Dart HttpClient class should be overridden to always return a failure response.
protected">@protectedread-only
pipelineOwner → PipelineOwner: The render tree's owner, which maintains dirty state for layout, composite, paint, and accessibility semantics.
read-onlyinherited
platformDispatcher → TestPlatformDispatcher: The ui.PlatformDispatcher to which this binding is bound.
read-onlyoverride
platformMenuDelegate ↔ PlatformMenuDelegate: A delegate that communicates with a platform plugin for serializing and managing platform-rendered menu bars created by PlatformMenuBar.
read / writeinherited
pointerEventSource → TestBindingEventSource: The source of the current pointer event.
read-only
pointerRouter → PointerRouter: A router that routes all pointer events received from the engine.
finalinherited
pointerSignalResolver → PointerSignalResolver: The resolver used for determining which widget handles a PointerSignalEvent.
finalinherited
registerTestTextInput → bool: Determines whether the binding automatically registers testTextInput as a fake keyboard implementation.
protected">@protectedread-only
renderView ↔ RenderView: The render tree that's attached to the output surface.
read / writeinherited
renderViewElement → Element?: The Element that is at the root of the hierarchy (and which wraps the RenderView object at the root of the rendering hierarchy).
read-onlyinherited
resamplingEnabled ↔ bool: Enable pointer event resampling for touch devices by setting this to true.
read / writeinherited
restorationManager → TestRestorationManager: The RestorationManager synchronizes the restoration data between engine and framework.
read-onlyoverride
runtimeType → Type: A representation of the runtime type of the object.
read-onlyinherited
samplingOffset ↔ Duration: Offset relative to current frame time that should be used for resampling. The samplingOffset is expected to be negative. Non-negative samplingOffset is allowed but will effectively disable resampling.
read / writeinherited
schedulerPhase → SchedulerPhase: The phase that the scheduler is currently operating under.
read-onlyinherited
schedulingStrategy ↔ SchedulingStrategy: The strategy to use when deciding whether to run a task or not.
read / writeinherited
sendFramesToEngine → bool: Whether frames produced by drawFrame are sent to the engine.
read-onlyinherited
showAppDumpInErrors ↔ bool: Whether to include the output of debugDumpApp() when reporting test failures.
read / write
systemFonts → Listenable: Listenable that notifies when the available fonts on the system have changed.
read-onlyinherited
testTextInput → TestTextInput: A stub for the system's onscreen keyboard. Callers must set the focusedEditable before using this value.
read-only
transientCallbackCount → int: The current number of transient frame callbacks scheduled.
read-onlyinherited
waitUntilFirstFrameRasterized → Future<void>: A future that completes when the Flutter engine has rasterized the first frame.
read-onlyinherited
window → TestWindow: The main window to which this binding is bound.
read-onlyoverride

Methods

addObserver(WidgetsBindingObserver observer) → void: Registers the given object as a binding observer. Binding observers are notified when various application events occur, for example when the system locale changes. Generally, one widget in the widget tree registers itself as a binding observer, and converts the system state into inherited widgets.
inherited
addPersistentFrameCallback(FrameCallback callback) → void: Adds a persistent frame callback.
inherited
addPostFrameCallback(FrameCallback callback) → void: Schedule a callback for the end of this frame.
inherited
addTime(Duration duration) → void: This method has no effect.
Deprecated('This method has no effect. ' 'This feature was deprecated after v2.6.0-1.0.pre.')">@Deprecated('This method has no effect. ' 'This feature was deprecated after v2.6.0-1.0.pre.')
addTimingsCallback(TimingsCallback callback) → void: Add a TimingsCallback that receives FrameTiming sent from the engine.
inherited
allowFirstFrame() → void: Called after deferFirstFrame to tell the framework that it is ok to send the first frame to the engine now.
inherited
asyncBarrier() → void: This is called during test execution before and after the body has been executed.
attachRootWidget(Widget rootWidget) → void: Takes a widget and attaches it to the renderViewElement, creating it if necessary.
inherited
cancelFrameCallbackWithId(int id) → void: Cancels the transient frame callback with the given id.
inherited
cancelPointer(int pointer) → void: Dispatch a PointerCancelEvent for the given pointer soon.
inherited
computePlatformResolvedLocale(List<Locale> supportedLocales) → Locale?: Computes the locale the current platform would resolve to.
inherited
createBinaryMessenger() → TestDefaultBinaryMessenger: Creates a default BinaryMessenger instance that can be used for sending platform messages.
inherited
createImageCache() → ImageCache: Creates the ImageCache singleton (accessible via imageCache).
protected">@protectedinherited
createRestorationManager() → TestRestorationManager: Creates the RestorationManager instance available via restorationManager.
override
createSemanticsUpdateBuilder() → SemanticsUpdateBuilder: Creates an empty semantics update builder.
inherited
createViewConfiguration() → ViewConfiguration: Returns a ViewConfiguration configured for the RenderView based on the current environment.
override
debugAssertNoTransientCallbacks(String reason) → bool: Asserts that there are no registered transient callbacks; if there are, prints their locations and throws an exception.
inherited
deferFirstFrame() → void: Tell the framework to not send the first frames to the engine until there is a corresponding call to allowFirstFrame.
inherited
delayed(Duration duration) → Future<void>: Delay for duration of time.
dispatchAccessibilityFeaturesChanged() → void: Notify all the observers that the active set of AccessibilityFeatures has changed (using WidgetsBindingObserver.didChangeAccessibilityFeatures), giving them the features argument.
mustCallSuper">@mustCallSuperprotected">@protectedinherited
dispatchEvent(PointerEvent event, HitTestResult? hitTestResult) → void: Dispatch an event to pointerRouter and the path of a hit test result.
inherited
dispatchLocalesChanged(List<Locale>? locales) → void: Notify all the observers that the locale has changed (using WidgetsBindingObserver.didChangeLocales), giving them the locales argument.
mustCallSuper">@mustCallSuperprotected">@protectedinherited
drawFrame() → void: Pump the build and rendering pipeline to generate a frame.
inherited
ensureFrameCallbacksRegistered() → void: Ensures callbacks for PlatformDispatcher.onBeginFrame and PlatformDispatcher.onDrawFrame are registered.
protected">@protectedinherited
ensureVisualUpdate() → void: Schedules a new frame using scheduleFrame if this object is not currently producing a frame.
inherited
evict(String asset) → void: Called in response to the ext.flutter.evict service extension.
inherited
globalToLocal(Offset point) → Offset: Convert the given point from the global coordinate space to the local one.
handleAccessibilityFeaturesChanged() → void: Called when the platform accessibility features change.
inherited
handleAppLifecycleStateChanged(AppLifecycleState state) → void: Called when the application lifecycle state changes.
inherited
handleBeginFrame(Duration? rawTimeStamp) → void: Called by the engine to prepare the framework to produce a new frame.
inherited
handleDrawFrame() → void: Called by the engine to produce a new frame.
inherited
handleEvent(PointerEvent event, HitTestEntry<HitTestTarget> entry) → void: Override this method to receive events.
inherited
handleEventLoopCallback() → bool: Execute the highest-priority task, if it is of a high enough priority.
visibleForTesting">@visibleForTestinginherited
handleLocaleChanged() → void: Called when the system locale changes.
mustCallSuper">@mustCallSuperprotected">@protectedinherited
handleMemoryPressure() → void: Called when the operating system notifies the application of a memory pressure situation.
inherited
handleMetricsChanged() → void: Called when the system metrics change.
inherited
handlePlatformBrightnessChanged() → void: Called when the platform brightness changes.
inherited
handlePointerEvent(PointerEvent event) → void: Dispatch an event to the targets found by a hit test on its position.
inherited
handlePointerEventForSource(PointerEvent event, {TestBindingEventSource source = TestBindingEventSource.device}) → void: Dispatch an event to the targets found by a hit test on its position, and remember its source as pointerEventSource.
handlePopRoute() → Future<void>: Called when the system pops the current route.
protected">@protectedinherited
handlePushRoute(String route) → Future<void>: Called when the host tells the app to push a new route onto the navigator.
mustCallSuper">@mustCallSuperprotected">@protectedinherited
handleSystemMessage(Object systemMessage) → Future<void>: Handler called for messages received on the SystemChannels.system message channel.
inherited
handleTextScaleFactorChanged() → void: Called when the platform text scale factor changes.
inherited
hitTest(HitTestResult result, Offset position) → void: Determine which HitTestTarget objects are located at a given position.
inherited
idle() → Future<void>: Acts as if the application went idle.
initInstances() → void: The initialization method. Subclasses override this method to hook into the platform and otherwise configure their services. Subclasses must call "super.initInstances()".
override
initLicenses() → void: Adds relevant licenses to the LicenseRegistry.
override
initMouseTracker([MouseTracker? tracker]) → void: Creates a MouseTracker which manages state about currently connected mice, for hover notification.
visibleForTesting">@visibleForTestinginherited
initRenderView() → void: Creates a RenderView object to be the root of the RenderObject rendering tree, and initializes it so that it will be rendered when the next frame is requested.
inherited
initServiceExtensions() → void: Called when the binding is initialized, to register service extensions.
inherited
instantiateImageCodec(Uint8List bytes, {int? cacheWidth, int? cacheHeight, bool allowUpscaling = false}) → Future<Codec>: Calls through to dart:ui.instantiateImageCodec from ImageCache.
Deprecated('Use instantiateImageCodecFromBuffer with an ImmutableBuffer instance instead. ' 'This feature was deprecated after v2.13.0-1.0.pre.')">@Deprecated('Use instantiateImageCodecFromBuffer with an ImmutableBuffer instance instead. ' 'This feature was deprecated after v2.13.0-1.0.pre.')inherited
instantiateImageCodecFromBuffer(ImmutableBuffer buffer, {int? cacheWidth, int? cacheHeight, bool allowUpscaling = false}) → Future<Codec>: Calls through to dart:ui.instantiateImageCodecFromBuffer from ImageCache.
inherited
localToGlobal(Offset point) → Offset: Convert the given point from the local coordinate space to the global one.
lockEvents(Future<void> callback()) → Future<void>: Locks the dispatching of asynchronous events and callbacks until the callback's future completes.
protected">@protectedinherited
noSuchMethod(Invocation invocation) → dynamic: Invoked when a non-existent method or property is accessed.
inherited
performReassemble() → Future<void>: This method is called by reassembleApplication to actually cause the application to reassemble, e.g. after a hot reload.
inherited
postEvent(String eventKind, Map<String, dynamic> eventData) → void: All events dispatched by a BindingBase use this method instead of calling developer.postEvent directly so that tests for BindingBase can track which events were dispatched by overriding this method.
protected">@protectedinherited
postTest() → void: Called by the testWidgets function after a test is executed.
pump([Duration? duration, EnginePhase newPhase = EnginePhase.sendSemanticsUpdate]) → Future<void>: Triggers a frame sequence (build/layout/paint/etc), then flushes microtasks.
readInitialLifecycleStateFromNativeWindow() → void: Initializes the lifecycleState with the dart:ui.PlatformDispatcher.initialLifecycleState.
protected">@protectedinherited
readTestInitialLifecycleStateFromNativeWindow() → void: Re-attempts the initialization of the lifecycle state after providing test values in TestWindow.initialLifecycleStateTestValue.
reassembleApplication() → Future<void>: Cause the entire application to redraw, e.g. after a hot reload.
inherited
registerBoolServiceExtension({required String name, required AsyncValueGetter<bool> getter, required AsyncValueSetter<bool> setter}) → void: Registers a service extension method with the given name (full name "ext.flutter.name"), which takes a single argument "enabled" which can have the value "true" or the value "false" or can be omitted to read the current value. (Any value other than "true" is considered equivalent to "false". Other arguments are ignored.)
protected">@protectedinherited
registerNumericServiceExtension({required String name, required AsyncValueGetter<double> getter, required AsyncValueSetter<double> setter}) → void: Registers a service extension method with the given name (full name "ext.flutter.name"), which takes a single argument with the same name as the method which, if present, must have a value that can be parsed by double.parse, and can be omitted to read the current value. (Other arguments are ignored.)
protected">@protectedinherited
registerServiceExtension({required String name, required ServiceExtensionCallback callback}) → void: Registers a service extension method with the given name (full name "ext.flutter.name").
protected">@protectedinherited
registerSignalServiceExtension({required String name, required AsyncCallback callback}) → void: Registers a service extension method with the given name (full name "ext.flutter.name"), which takes no arguments and returns no value.
protected">@protectedinherited
registerStringServiceExtension({required String name, required AsyncValueGetter<String> getter, required AsyncValueSetter<String> setter}) → void: Registers a service extension method with the given name (full name "ext.flutter.name"), which optionally takes a single argument with the name "value". If the argument is omitted, the value is to be read, otherwise it is to be set. Returns the current value.
protected">@protectedinherited
removeObserver(WidgetsBindingObserver observer) → bool: Unregisters the given observer. This should be used sparingly as it is relatively expensive (O(N) in the number of registered observers).
inherited
removeTimingsCallback(TimingsCallback callback) → void: Removes a callback that was earlier added by addTimingsCallback.
inherited
reportExceptionNoticed(FlutterErrorDetails exception) → void: Called when the framework catches an exception, even if that exception is being handled by takeException.
protected">@protected
reset() → void: Called by the test framework at the beginning of a widget test to prepare the binding for the next test.
resetEpoch() → void: Prepares the scheduler for a non-monotonic change to how time stamps are calculated.
inherited
resetFirstFrameSent() → void: Call this to pretend that no frames have been sent to the engine yet.
inherited
resetGestureBinding() → void: Reset states of GestureBinding.
protected">@protectedinherited
runAsync<T>(Future<T> callback(), {Duration additionalTime = const Duration(milliseconds: 1000)}) → Future<T?>: Runs a callback that performs real asynchronous work.
runTest(Future<void> testBody(), VoidCallback invariantTester, {String description = '', Duration? timeout}) → Future<void>: Call the testBody inside a FakeAsync scope on which pump can advance time.
scheduleAttachRootWidget(Widget rootWidget) → void: Schedules a Timer for attaching the root widget.
protected">@protectedinherited
scheduleForcedFrame() → void: Schedules a new frame by calling dart:ui.PlatformDispatcher.scheduleFrame.
inherited
scheduleFrame() → void: If necessary, schedules a new frame by calling dart:ui.PlatformDispatcher.scheduleFrame.
inherited
scheduleFrameCallback(FrameCallback callback, {bool rescheduling = false}) → int: Schedules the given transient frame callback.
inherited
scheduleTask<T>(TaskCallback<T> task, Priority priority, {String? debugLabel, Flow? flow}) → Future<T>: Schedules the given task with the given priority and returns a Future that completes to the task's eventual return value.
inherited
scheduleWarmUpFrame() → void: Schedule a frame to run as soon as possible, rather than waiting for the engine to request a frame in response to a system "Vsync" signal.
inherited
setLocale(String languageCode, String countryCode) → Future<void>: Artificially calls dispatchLocalesChanged on the Widget binding, then flushes microtasks.
setLocales(List<Locale> locales) → Future<void>: Artificially calls dispatchLocalesChanged on the Widget binding, then flushes microtasks.
setSemanticsEnabled(bool enabled) → void: Whether the render tree associated with this binding should produce a tree of SemanticsNode objects.
inherited
setSurfaceSize(Size? size) → Future<void>: Artificially changes the surface size to size on the Widget binding, then flushes microtasks.
setSystemUiChangeCallback(SystemUiChangeCallback? callback) → void: Sets the callback for the SystemChrome.systemUIChange method call received on the SystemChannels.platform channel.
inherited
takeException() → dynamic: Returns the exception most recently caught by the Flutter framework.
toString() → String: A string representation of this object.
inherited
unlocked() → void: Called by lockEvents when events get unlocked.
inherited
withPointerEventSource(TestBindingEventSource source, VoidCallback task) → void: Sets pointerEventSource to source, runs task, then resets source to the previous value.
protected">@protected

Operators

operator ==(Object other) → bool: The equality operator.
inherited

Static Properties

instance → TestWidgetsFlutterBinding: The current TestWidgetsFlutterBinding, if one has been created.
read-onlyoverride

Static Methods

ensureInitialized([Map<String, String>? environment]) → TestWidgetsFlutterBinding: Creates and initializes the binding. This function is idempotent; calling it a second time will just return the previously-created instance.