StatefulWidget Unit test 작성 방법

Flutter 에서 inheritedWidget으로 state 구현 시, 

StatefulWidget의 State안에 있는 method의 unit test 구현

핵심은 아래 구문을 통해 State객체를 얻어올 수 있다는 것이다.

void main() {
  group('AppStateContainer', () {
    testWidgets('Test ranking', (WidgetTester tester) async {
      await tester.pumpWidget(AppStateContainer(
          child: new AppRootWidget('/'), state: new AppState()));

      final AppStateContainerState appStateContainerState =
          tester.state(find.byType(AppStateContainer));
      appStateContainerState.state.singlePlayRecords = [];
      for (int i = 1; i <= 10; i++) {
        appStateContainerState.state.singlePlayRecords.add(new Record(
            record: i * 0.001,
            timeStamp: DateTime.now().millisecondsSinceEpoch));
      }
      expect(
          appStateContainerState.getRankFromRecord(new Record(
              record: 0.001, timeStamp: DateTime.now().millisecondsSinceEpoch)),
          2);
      expect(
          appStateContainerState.getRankFromRecord(new Record(
              record: 0.0001, timeStamp: DateTime.now().millisecondsSinceEpoch)),
          1);
    });
  });
}

<참고> https://github.com/flutter/flutter/blob/master/packages/flutter/test/widgets/stateful_components_test.dart