How to make a promise to be rejected in a Jest Manual Mock












0















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);
});
})









share|improve this question





























    0















    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);
    });
    })









    share|improve this question



























      0












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      0








      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);
      });
      })









      share|improve this question
















      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);
      });
      })






      reactjs typescript unit-testing jestjs enzyme






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      edited Nov 16 '18 at 7:36









      skyboyer

      3,44111128




      3,44111128










      asked Nov 16 '18 at 1:37









      OscarSOscarS

      13




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