Ndtyjky

I have a component that after being mounted calls a function to get some data from pouchdb. I have a driver/facade that uses the pouchdb api internally to get this data after syncing with a remote database. Now for my test i have provided a manual mock so I can mock the result/response to avoid using pouchdb directly. This is working fine but I now want to test the reject block and since my manual mock always resolves I'm getting stock on how to test this part. Here is my test :

Component Code

 // getData gets called in componentDidMount

 public getData() {

  // The test will use the mock implementation which returns a 

  // resolved promise

  this.driver.getData().then(

    (sessions: Session) => {

      this.setState({

        dataSource: this.state.dataSource.cloneWithRows(sessions),

        didSync: true,

        sessions: sessions

      });

    },

    // How can I force my mock implementation to reject the promise so 

    // I can test this block ?

    error => {

      // Send a log error to a backend API

      this.setState({ didSync: false });

    }

  );

}

Test

// This uses the mock implementation which returns a promise

jest.mock("../../../modules/pouchdb/WebDriver"); 

let wrapper: ShallowWrapper | ReactWrapper;

let instance;

// This is the response my mock driver returns

const data = SessionsQAResponseMock.getSessionsResponse();



describe('My Component Tests', () => {

beforeEach(() => {

  wrapper = shallow(<AttendeesHomeComponent userRole={Roles.Attendee} 

/>);

  instance = wrapper.instance();

  expect(wrapper).toMatchSnapshot();

});



// This tests works (Successful Promise)

it('Tests Resolves Promise', done => {

  const emptyContent = wrapper.find(EmptyContentComponent);

  expect(emptyContent.exists()).toBeTruthy();

  expect(instance.state.didSync).toBeFalsy();

  expect(instance.state.sessions).toEqual();

  setTimeout(() => {

    // Webdriver resolves

    expect(instance.state.didSync).toBeTruthy();

    expect(instance.state.sessions).toEqual(data);

    // After we got data our component should display a ListView

    const listView = wrapper.find(ListView);

    expect(listView.exists()).toBeTruthy();

    // We're done testing

    done();

   }, 0);

});



// This test fails. The mock is still resolving the promise. and the 

// states updates to {dydSync: true}

it("Test Error Block", done => {

  // driver is an instance variable    

  instance.driver.getSessions = jest.fn()

  .mockReturnValue(Promise.reject({ error: "Failed" }));

  setTimeout(() => {

    // expect(instance.state.sessions).toEqual();

    expect(instance.state.didSync).toBeFalsy();

    done();

  }, 0);

});

})