Flutter's blocTest is calling expect too early

I'm writing a test using flutter_bloc and the bloc_test libraries, which looks something like this:

blocTest(
    'description',
    build: () => myBloc,
    act: (bloc) {
        bloc.add(SomeEvent(stuff));
    },
    expect: [firstState, secondState],
)

Unfortunately, when myBloc calls out to the repository, the repository awaits on a gRPC call (to a fake gRPC service), and the expect call runs before myBloc has a chance to emit any states. How should I handle this?

Ideas I've considered:

• Set blocTest.wait to some Duration. This works, but it's hacky! and slow!
• Mock my repository. I tend to dislike this approach, because the repository outputs multiple values for each update. The interactions are pretty verbose to mock in every test. Instead, I opted to mock the data sources the repository talks to, by writing a fake gRPC service.
• Write something so I can change the act callback to look something like this:

act: (bloc) async {
    // I don't know what this could be yet. Some setup for later.
    bloc.onEvent(doSomethingSmart);
    bloc.add(SomeEvent(stuff));
    // Block until we have some set of states, but this is basically what expect does.
    await somethingSmart.expect([firstState, secondState]);
    // or alternatively, just wait for N events
    await somethingSmart.expectNumEvents(2);
},

Is there something like this already? Are there other suggestions for how to handle this?