RxBlocking.swift

let disposeBag = DisposeBag()
Observable.of(.signIn(email: self.invalidEmail, password: self.defaultPassword))
    .delay(1, scheduler: MainScheduler.instance)
    .bind(to: self.signInReactor.action)
    .disposed(by: disposeBag)

guard let state = try? self.signInReactor.state.skip(1).take(1).toBlocking(timeout: 5).first(), let errorMessage = state?.errorMessage else {
    fail("It should emit error state")
    return
}
expect(errorMessage).to(equal(SignInReactor.ErrorMessage.invalidEmail), description: "It should show the correct error message")