How can I do this in Flutter Testing

Question

I'm new to Flutter testing and was hoping If you could help me. I've a class called AddShimmer that looks like this ->

AddShimmer(
          child: ListTile(
            title: buildLoadingAnimation(context),
          ),
        ),

Now, I'm trying to write a flutter test just to check if a child widget is being passed to the AddShimmer class. To do that, I'm writing something like this ->

testWidgets('Shimmer has a child widget', (WidgetTester tester) async {
    const childWidget = ListTile(
      title: Text('Loading'),
    );
    await tester.pumpWidget(
     const AddShimmer(child: childWidget)
    );
    expect(find.byWidget(childWidget), findsOneWidget);
  });

While I'm executing the test, I'm getting an exception which says ->

The following assertion was thrown building ListTile(dirty):
No Directionality widget found.
ListTile widgets require a Directionality widget ancestor.
The specific widget that could not find a Directionality ancestor was:
  ListTile

What does it mean and how to test this out ??

mmcdon20 · Accepted Answer · 2021-12-20 04:45:37Z

2

Basically flutter needs some additional context in order to render the widget. I usually just wrap it in a Scaffold inside a MaterialApp.

await tester.pumpWidget(
  const MaterialApp(
    home: Scaffold(
      body: AddShimmer(child: childWidget),
    ),
  ),
);

answered Dec 20, 2021 at 4:45

mmcdon20

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4 Comments

Divyam Dhadwal Over a year ago

Got it! DO i need to do this for every test case that I write ?? I mean for all the widgets out there ? All wrapped within the Scaffold and material app?

mmcdon20 Over a year ago

Some basic widgets like await tester.pumpWidget(Container()); don't seem to need the additional context. Also, if the widget already has a MaterialApp and Scaffold inside it, it would not need to be wrapped inside another MaterialApp and Scaffold. So it depends.

Divyam Dhadwal Over a year ago

Alright. Thanks for the help :) Really appreciate it.

mmcdon20 Over a year ago

I should note that you could instead wrap AddShimmer(child: childWidget) in a Directionality widget, as the error message suggests, but then you will get another error saying it needs to be inside a Material widget, and then inside a MediaQuery and so on. Wrapping in a MaterialApp and Scaffold just happens to be easier in my experience.

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