Watch query test harness - Unit testing Flutter GraphQL

helpers.dart

MockQueryResult<T> generateMockWatchQuery<T>(MockGraphQLClient graphQLClient) {
  registerFallbackValue(_FakeWatchQueryOptions<T>());

  final query = MockObservableQuery<T>();
  final result = MockQueryResult<T>();

  when(query.close).thenReturn(QueryLifecycle.closed);
  when(() => query.stream).thenAnswer((_) => Stream.value(result));
  when(() => query.latestResult).thenReturn(result);
  when(
    () => query.onData(
      any(),
      removeAfterInvocation: any(named: 'removeAfterInvocation'),
    ),
  ).thenReturn(() {});
  when(() => graphQLClient.watchQuery<T>(any())).thenReturn(query);

  final queryManager = graphQLClient.queryManager;
  when(() => queryManager.watchQuery<T>(any())).thenReturn(query);

  return result;
}

class MockQueryResult<T> extends Mock implements QueryResult<T> {}

class _FakeWatchQueryOptions<T> extends Fake implements WatchQueryOptions<T> {}

class MockObservableQuery<T> extends Mock implements ObservableQuery<T> {}