How to cover lines in mapDispatchToProps with Jest?

Question

My question is how do we cover these lines in jest?

export const mapDispatchToProps = dispatch => {
    return {
        submitClaimsForm: form => {
            dispatch(submitClaimsForm(form));
        }
    };
};

---

In my component this is what the redux connected area looks like:

export function mapStateToProps(state) {
    return {
        formNonMember: state.form,
        submissionSuccess: state.claimSubmission.submissionSuccess
    };
}

export const mapDispatchToProps = dispatch => {
    return {
        submitClaimsForm: form => {
            dispatch(submitClaimsForm(form));
        }
    };
};

let AdditionalDetailsFormConnect = reduxForm({
    form: 'AdditionalDetails',
    destroyOnUnmount: false
})(AdditionalDetailsForm);

export default connect(
    mapStateToProps,
    mapDispatchToProps
)(AdditionalDetailsFormConnect);

And this is how the dispatched action is used:

onSubmit() {
    this.props.submitClaimsForm(this.props.formattedForm);
}

Next this is what the actual action looks like:

import {postClaimsForm} from '../shared/services/api';

export const Actions = {
    SET_SUBMISSION_STATUS: 'SET_SUBMISSION_STATUS'
};

export const submitClaimsForm = form => dispatch => {
    return postClaimsForm(form)
        .then(res => {
            // console.log('promise returned:', res);
            return dispatch({
                type: Actions.SET_SUBMISSION_STATUS,
                submissionSuccess: true
            });
        })
        .catch(error => {
            // console.log('error returned:', error);
            return dispatch({
                type: Actions.SET_SUBMISSION_STATUS,
                submissionSuccess: false
            });
        });
};

What I've tried so far:

it('mapDispatchToProps works as expected', () => {
    const actionProps = mapDispatchToProps({
        submitClaimsForm: jest.fn()
    });
    actionProps.submitClaimsForm();
    expect(submitClaimsForm).toHaveBeenCalled();
});

But this errors and tells me that dispatch is undefined.

I also have this test, which passes, it tells me that submitClaimsForm has been called, but it just covers the lines for onSubmit:

it('onSubmit is called on submit', function() {
    const spyOnSubmit = jest.spyOn(wrapper.instance(), 'onSubmit');
    const mockHandleSubmit = jest.fn(wrapper.instance().onSubmit);
    const submitClaimsForm = jest.fn(wrapper.instance().submitClaimsForm);

    wrapper.setProps({
        handleSubmit: mockHandleSubmit,
        submitClaimsForm
    });

    wrapper.find('MyForm').simulate('submit');

    expect(mockHandleSubmit).toHaveBeenCalled();
    expect(spyOnSubmit).toHaveBeenCalled();
    expect(submitClaimsForm).toHaveBeenCalled();  // <--
});

Answer 1

The reason your mapDispatchToProps works as expected test fails is because mapDispatchToProps expects a dispatch function to be passed in, not the map itself (that's what mapDispatchToProps returns).

This should work:

jest.mock('./actions');
import * as actions from './actions';

it('mapDispatchToProps calls the appropriate action', async () => {
  // mock the 'dispatch' object
  const dispatch = jest.fn();
  const actionProps = mapDispatchToProps(dispatch);
  const formData = { ... };
  actionProps.submitClaimsForm(formData);
  // verify the appropriate action was called
  expect(actions.submitClaimsForm).toHaveBeenCalled(formData);
});