This implementation is pretty simple. I'm going to create a new StatelessWidget that uses an extended FAB with a G logo and text. onPressed will kick off the authentication flow in the future, but for now it just prints that the FAB was tapped.
classSignInFabextendsStatelessWidget{constSignInFab();@overrideWidgetbuild(BuildContextcontext){returnFloatingActionButton.extended(onPressed:()=>print('Tapped on sign in'),icon:Image.asset('assets/google_g_logo.png',height:24.0),label:constText('Sign in with Google'),);}}
The tests for SignInFab simply check that the expected elements are still there.
In addition to adding floatingActionButton to the Scaffold in _MyHomePageState, I'm also adding accentColor to the theme. The accentColor is usually complementary to the primaryColor but I want them both to be white for now. accentColor will be used as the default background of FABs.