Flutter: testing widgets

Question

what I'm trying to test is: the user taps a button and the snackbar is shown for five second.

Here is the scaffold with its key:

final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>(debugLabel: "scaffoldState");

...

builder: (context, viewModel) => Scaffold(
              key: _scaffoldKey,

Then the code for the button and the snackBar:

child: FlatButton(key: Key('loginButton'), onPressed: () { 
 validate();

...

  validate() {
    // FormState object can be used to save, reset, and validate
    // every FormField that is a descendant of the associated Form.

    final FormState form = _formKey.currentState;

    if (form.validate()) {
      form.save();
      form.reset();

      //implementation of the snackBar:
      _scaffoldKey.currentState.showSnackBar(new SnackBar(
        duration: new Duration(seconds: 5)

...

And I am trying to test this behaviour in this way (I'm using also Flutter redux):

void main(){

  final store = Store<AppState>(reducer, initialState: AppState.initialState());
  testWidgets("MaterialApp local", (WidgetTester tester) async{
    await tester.pumpWidget(new StoreProvider(
        store: store,
        child: MaterialApp(
          home: LoginView(),
        )));
    await tester.pumpAndSettle();
    await tester.press(find.byKey(Key("loginButton")));
    expect();

I don't know what to put inside expect. I was trying to take the GlobalKey using find.ByKey(Key)) and to search for the debugLabel, but it doesn't seem to work. I'm trying since 2 days, but I can't find a way out.

Schnodderbalken · Accepted Answer · 2020-10-02 12:42:34Z

2

It might be a little late to answer this, but since it was the second result on Google when typing "Flutter test Snackbar", I will just give my two cents:

It's actually pretty simple. Don't think of the Snackbar as being something completely different only because it only resides at the bottom for a few seconds. Lastly, the Snackbar is just another Widget.

Keeping this in mind you can test it as follows:

testWidgets("MaterialApp local", (WidgetTester tester) async{
  ...
  // Test if the Snackbar appears
  expect(find.byType(SnackBar), findsOneWidget);
  // Test if it contains your text
  expect(find.text('TAPS!'), findsOneWidget);
});

answered Oct 2, 2020 at 12:42

Schnodderbalken

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Comments

Angga Dwi · Accepted Answer · 2018-10-05 04:24:11Z

0

i actually met the same condition as you did, and all i did is put a text as the content of the snackbar.

for showing the snackbar, the code i use is

scaffoldKey.currentState.showSnackBar(SnackBar(content: Text("TAPS!"),));
          }, "SEE ALL", backgroundColor: Colors.red, textColor: Colors.blue)

and i expect to find a text with the same content as i put in, and add findsOneWidget.

expect(find.text("TAPS!"), findsOneWidget);

answered Oct 5, 2018 at 4:24

Angga Dwi

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