TestWidgetsFlutterBinding class

Base class for bindings used by widgets library tests.

The ensureInitialized method creates (if necessary) and returns an instance of the appropriate subclass.

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

Mixed in types


Constructor for TestWidgetsFlutterBinding. [...]


checkIntrinsicSizes bool
The value to set debugCheckIntrinsicSizes to while tests are running. [...]
@protected, read-only
clock Clock
The current time. [...]
debugPrintOverride DebugPrintCallback
The value to set debugPrint to while tests are running. [...]
@protected, read-only
defaultTestTimeout Timeout
The default maximum test timeout for tests when using this binding. [...]
disableShadows bool
The value to set debugDisableShadows to while tests are running. [...]
@protected, read-only
focusedEditable EditableTextState
The current client of the onscreen keyboard. Callers must pump an additional frame after setting this property to complete the the focus change. [...]
read / write
inTest bool
Whether there is currently a test executing.
microtaskCount int
The number of outstanding microtasks in the queue.
showAppDumpInErrors bool
Whether to include the output of debugDumpApp() when reporting test failures.
read / write
testTextInput TestTextInput
A stub for the system's onscreen keyboard. Callers must set the focusedEditable before using this value.
window TestWindow
The window to which this binding is bound. [...]
read-only, override
accessibilityFeatures AccessibilityFeatures
The currently active set of AccessibilityFeatures.
read-only, inherited
buildOwner BuildOwner
The BuildOwner in charge of executing the build pipeline for the widget tree rooted at this binding.
read-only, inherited
currentFrameTimeStamp Duration
The time stamp for the frame currently being processed.
read-only, inherited
currentSystemFrameTimeStamp Duration
The raw time stamp as provided by the engine to Window.onBeginFrame for the frame currently being processed.
read-only, inherited
debugBuildingDirtyElements bool
Whether we are currently in a frame. This is used to verify that frames are not scheduled redundantly.
@protected, read / write, inherited
debugDidSendFirstFrameEvent bool
Whether the first frame has finished building.
read-only, inherited
defaultBinaryMessenger BinaryMessenger
The default instance of BinaryMessenger.
read-only, inherited
disableAnimations bool
The platform is requesting that animations be disabled or simplified.
read-only, inherited
endOfFrame Future<void>
Returns a Future that completes after the frame completes.
read-only, inherited
firstFrameRasterized bool
Whether the Flutter engine has rasterized the first frame.
read-only, inherited
focusManager FocusManager
The object in charge of the focus tree.
read-only, inherited
framesEnabled bool
Whether frames are currently being scheduled when scheduleFrame is called.
read-only, inherited
gestureArena GestureArenaManager
The gesture arenas used for disambiguating the meaning of sequences of pointer events.
final, inherited
hashCode int
The hash code for this object. [...]
read-only, inherited
hasScheduledFrame bool
Whether this scheduler has requested that handleBeginFrame be called soon.
read-only, inherited
imageCache ImageCache
The singleton that implements the Flutter framework's image cache.
read-only, inherited
isRootWidgetAttached bool
Whether the renderViewElement has been initialized.
read-only, inherited
lifecycleState AppLifecycleState
Whether the application is visible, and if so, whether it is currently interactive.
read-only, inherited
locked bool
Whether lockEvents is currently locking events.
@protected, read-only, inherited
mouseTracker MouseTracker
The object that manages state about currently connected mice, for hover notification.
read-only, inherited
pipelineOwner PipelineOwner
The render tree's owner, which maintains dirty state for layout, composite, paint, and accessibility semantics
read-only, inherited
pointerRouter PointerRouter
A router that routes all pointer events received from the engine.
final, inherited
pointerSignalResolver PointerSignalResolver
The resolver used for determining which widget handles a pointer signal event.
final, inherited
renderView RenderView
The render tree that's attached to the output surface.
read / write, inherited
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-only, inherited
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited
schedulerPhase SchedulerPhase
The phase that the scheduler is currently operating under.
read-only, inherited
schedulingStrategy SchedulingStrategy
The strategy to use when deciding whether to run a task or not.
read / write, inherited
systemFonts Listenable
Listenable that notifies when the available fonts on the system have changed.
read-only, inherited
transientCallbackCount int
The current number of transient frame callbacks scheduled.
read-only, inherited
waitUntilFirstFrameRasterized Future<void>
A future that completes when the Flutter engine has rasterized the first frame.
read-only, inherited


addTime(Duration duration) → void
Increase the timeout for the current test by the given duration. [...]
asyncBarrier() → void
This is called during test execution before and after the body has been executed. [...]
createBinaryMessenger() BinaryMessenger
Creates a default BinaryMessenger instance that can be used for sending platform messages.
createViewConfiguration() ViewConfiguration
Returns a ViewConfiguration configured for the RenderView based on the current environment. [...]
dispatchEvent(PointerEvent event, HitTestResult hitTestResult, {TestBindingEventSource source: TestBindingEventSource.device}) → void
Dispatch an event to a hit test result's path. [...]
globalToLocal(Offset point) Offset
Convert the given point from the global coordinate system (as used by pointer events from the device) to the coordinate system used by the tests (an 800 by 600 window).
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()". [...]
initLicenses() → void
Adds relevant licenses to the LicenseRegistry. [...]
localToGlobal(Offset point) Offset
Convert the given point from the coordinate system used by the tests (an 800 by 600 window) to the global coordinate system (as used by pointer events from the device).
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. [...]
readTestInitialLifecycleStateFromNativeWindow() → void
Re-attempts the initialization of the lifecycle state after providing test values in TestWindow.initialLifecycleStateTestValue.
reportExceptionNoticed(FlutterErrorDetails exception) → void
Called when the framework catches an exception, even if that exception is being handled by takeException. [...]
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. [...]
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.
setSurfaceSize(Size size) Future<void>
Artificially changes the surface size to size on the Widget binding, then flushes microtasks. [...]
takeException() → dynamic
Returns the exception most recently caught by the Flutter framework. [...]
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.
addPersistentFrameCallback(FrameCallback callback) → void
Adds a persistent frame callback.
addPostFrameCallback(FrameCallback callback) → void
Schedule a callback for the end of this frame.
addTimingsCallback(TimingsCallback callback) → void
Add a TimingsCallback that receives FrameTiming sent from the engine.
allowFirstFrameReport() → void
When called after deferFirstFrameReport: tell the framework to report the frame it is building as a "useful" first frame.
attachRootWidget(Widget rootWidget) → void
Takes a widget and attaches it to the renderViewElement, creating it if necessary.
cancelFrameCallbackWithId(int id) → void
Cancels the transient frame callback with the given id.
cancelPointer(int pointer) → void
Dispatch a PointerCancelEvent for the given pointer soon.
createImageCache() ImageCache
Creates the ImageCache singleton (accessible via imageCache).
@protected, inherited
debugAssertNoTransientCallbacks(String reason) bool
Asserts that there are no registered transient callbacks; if there are, prints their locations and throws an exception.
deferFirstFrameReport() → void
Tell the framework not to report the frame it is building as a "useful" first frame until there is a corresponding call to allowFirstFrameReport.
dispatchAccessibilityFeaturesChanged() → void
Notify all the observers that the active set of AccessibilityFeatures has changed (using WidgetsBindingObserver.didChangeAccessibilityFeatures), giving them the features argument.
@mustCallSuper, @protected, inherited
dispatchLocalesChanged(List<Locale> locales) → void
Notify all the observers that the locale has changed (using WidgetsBindingObserver.didChangeLocales), giving them the locales argument.
@mustCallSuper, @protected, inherited
drawFrame() → void
Pump the build and rendering pipeline to generate a frame.
ensureFrameCallbacksRegistered() → void
@protected, inherited
ensureVisualUpdate() → void
Schedules a new frame using scheduleFrame if this object is not currently producing a frame.
evict(String asset) → void
Called in response to the ext.flutter.evict service extension.
handleAccessibilityFeaturesChanged() → void
Called when the platform accessibility features change.
handleAppLifecycleStateChanged(AppLifecycleState state) → void
Called when the application lifecycle state changes.
handleBeginFrame(Duration rawTimeStamp) → void
Called by the engine to prepare the framework to produce a new frame.
handleDrawFrame() → void
Called by the engine to produce a new frame.
handleEvent(PointerEvent event, HitTestEntry entry) → void
Override this method to receive events.
handleEventLoopCallback() bool
Execute the highest-priority task, if it is of a high enough priority.
@visibleForTesting, inherited
handleLocaleChanged() → void
Called when the system locale changes.
@mustCallSuper, @protected, inherited
handleMemoryPressure() → void
Called when the operating system notifies the application of a memory pressure situation.
handleMetricsChanged() → void
Called when the system metrics change.
handlePlatformBrightnessChanged() → void
Called when the platform brightness changes.
handlePopRoute() Future<void>
Called when the system pops the current route.
@protected, inherited
handlePushRoute(String route) Future<void>
Called when the host tells the app to push a new route onto the navigator.
@mustCallSuper, @protected, inherited
handleSystemMessage(Object systemMessage) Future<void>
Handler called for messages received on the SystemChannels.system message channel.
handleTextScaleFactorChanged() → void
Called when the platform text scale factor changes.
hitTest(HitTestResult result, Offset position) → void
Determine which HitTestTarget objects are located at a given position.
initMouseTracker([MouseTracker tracker]) → void
Creates a MouseTracker which manages state about currently connected mice, for hover notification.
@visibleForTesting, inherited
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.
initServiceExtensions() → void
Called when the binding is initialized, to register service extensions.
instantiateImageCodec(Uint8List bytes, {int cacheWidth, int cacheHeight}) Future<Codec>
Calls through to dart:ui with decodedCacheRatioCap from ImageCache.
lockEvents(Future<void> callback()) Future<void>
Locks the dispatching of asynchronous events and callbacks until the callback's future completes.
@protected, inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed. [...]
performReassemble() Future<void>
This method is called by reassembleApplication to actually cause the application to reassemble, e.g. after a hot reload.
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, inherited
readInitialLifecycleStateFromNativeWindow() → void
Initializes the lifecycleState with the initialLifecycleState from the window.
@protected, inherited
reassembleApplication() Future<void>
Cause the entire application to redraw, e.g. after a hot reload.
registerBoolServiceExtension({String name, AsyncValueGetter<bool> getter, 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, inherited
registerNumericServiceExtension({String name, AsyncValueGetter<double> getter, 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, inherited
registerServiceExtension({String name, ServiceExtensionCallback callback}) → void
Registers a service extension method with the given name (full name "ext.flutter.name").
@protected, inherited
registerSignalServiceExtension({String name, 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, inherited
registerStringServiceExtension({String name, AsyncValueGetter<String> getter, 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, inherited
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).
removeTimingsCallback(TimingsCallback callback) → void
Removes a callback that was earlier added by addTimingsCallback.
resetEpoch() → void
Prepares the scheduler for a non-monotonic change to how time stamps are calculated.
scheduleAttachRootWidget(Widget rootWidget) → void
Schedules a Timer for attaching the root widget.
@protected, inherited
scheduleForcedFrame() → void
Schedules a new frame by calling Window.scheduleFrame.
scheduleFrame() → void
If necessary, schedules a new frame by calling Window.scheduleFrame.
scheduleFrameCallback(FrameCallback callback, {bool rescheduling: false}) int
Schedules the given transient frame callback.
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.
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.
setSemanticsEnabled(bool enabled) → void
Whether the render tree associated with this binding should produce a tree of SemanticsNode objects.
toString() String
Returns a string representation of this object.
unlocked() → void
Called by lockEvents when events get unlocked.


operator ==(dynamic other) bool
The equality operator. [...]

Static Methods

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