unregister method
Removes this object as a mock handler for SystemChannels.textInput.
After calling this method, the channel will exchange messages with the Flutter engine instead of the stub.
Called by the binding at the end of a (successful) test when TestWidgetsFlutterBinding.registerTestTextInput is true.
Implementation
void unregister() => TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.textInput, null);