How can I test chained promises in a Jest test?

Question

Below I have a test for my login actions. I\'m mocking a Firebase function and want to test if the signIn/signOut functions are called.

The

Answer 1

You have two issues here,

The tests pass however I do not see my 2nd console log. Which is this line console.log('store ==>', store);.

That is because the test is not waiting for the promise to fulfill, so you should return it:

it('signOut should call firebase', () => {
    console.log('signOut should call firebasew');
    return store.dispatch(signOut()).then(() => { // NOTE we return the promise
      expect(mockFirebaseService).toHaveBeenCalled();
      console.log('store ==>', store);
      expect(store.getActions()).toEqual({
        type: USER_ON_LOGGED_OUT
      });
      console.log('END');
    });

  });

You can find examples in the Redux official documentation.

Secondly, your signIn test is failing because you have mocked the wrong firebase:

jest.mock('services/firebase', () => new Promise(resolve => resolve(true)));

That should probably look more like:

jest.mock('services/firebase', () => new Promise(resolve => resolve({
    signInWithEmailAndPassword: () => { return { getIdToken: () => '123'; } }
})));

Answer 2

Login actions › signIn should call firebase

TypeError: auth.signInWithEmailAndPassword is not a function

This tells that your store.dispatch(signIn(user.email, user.password)) fails, thus your second console.log won't go into your then chain, use catch or second callback argument of then instead.