Testing fireAndForget effect

[maxkazakov]

Hey! I use version 0.39.1 with the Effects on Publishers.

I have a reducer which is responsible for saviging data to file:

let workoutPlansListSaveReducer = Reducer<WorkoutPlansList, WorkoutPlansListAction, WorkoutPlansListEnvironment> {  state, action, env in
    enum SaveToken {}
    return env.workoutPlansStorage.store(state.workoutPlans.elements)
        .debounce(id: SaveToken.self, for: 0.5, scheduler: env.mainQueue)
        .fireAndForget()
}

This reducer reacts on every action and it is combined with main logic reducer.

I want to test only main logic reducer without taking into account workoutPlansListSaveReducer's Effect, and I obviously receive "An effect returned for this action is still running." error. So, I have to append self.mainQueue.advance(by: .0.5) to the end of every test case.

Is there a smarter way to make test passed (without just advancing scheduler) ?
Is there a way to test workoutPlansListSaveReducer's Effect?

[Alex293]

Just pass you main reducer to the test store instead of passing the merged reducers

[maxkazakov]

Thanks! This is one of the option. But I'm still looking for a way to test combined reducer and to make sure that fireAndForget effect was called.

[mbrandonw]

Have you tried using an immediate scheduler for there mainQueue during tests? For example, this test passes:

func testImmediateDebounce() async {
  enum Action { case tap }
  let store = TestStore(
    initialState: 0,
    reducer: Reducer<Int, Action, Void> { state, action, _ in
      return .fireAndForget {
      }
      .debounce(id: 1, for: 1, scheduler: DispatchQueue.immediate)

    },
    environment: ()
  )

  await store.send(.tap)
}

[maxkazakov]

This test passes even if I just return .none from the reducer. Is there a way to make sure that .fireAndForget effect was invoked?

[mbrandonw]

Oh yes, you would mock the env.workoutPlansStorage.store endpoint to mutate a bit of local state in your test, and then assert on it after.

In my example above this would look roughly like the following:

func testImmediateDebounce() async {
  enum Action { case tap }
  let store = TestStore(
    initialState: 0,
    reducer: Reducer<Int, Action, Environment> { state, action, environment in
      return .fireAndForget {
        environment.save()
      }
      .debounce(id: 1, for: 1, scheduler: DispatchQueue.immediate)

    },
    environment: ()
  )

  var saveCount = 0
  store.environment.save = { _ in saveCount += 1 }

  await store.send(.tap)
  XCTAssertEqual(saveCount, 1)
}

[maxkazakov]

Thank you!