Jest helper for Redux component testing

__mocks__\react-redux.js

const mockDispatch = () => {};

function mapEverything(mapStateToProps, mapDispatchToProps, mergeProps, state, ownProps) {
  const stateProps = mapStateToProps
    ? mapStateToProps(state, ownProps)
    : {};

  const dispatchProps = mapDispatchToProps
    ? mapDispatchToProps(mockDispatch, ownProps)
    : {
      dispatch: mockDispatch,
    };

  const mergedProps = mergeProps
    ? mergeProps(stateProps, dispatchProps, ownProps)
    : {
      ...stateProps,
      ...dispatchProps,
      ...ownProps,
    };

  return mergedProps;
}

module.exports = {

  Provider: ({ children }) => children,

  /**
   * Returns a modified redux connector which adds a
   * new method `getMappedProps` to the component for testing purposes.
   */
  connect: (mapStateToProps, mapDispatchToProps, mergeProps) => (component) => {
    // Provide access to the mapped props from the component.
    // eslint-disable-next-line no-param-reassign
    component.getMappedProps = (state = {}, ownProps = {}) =>
      mapEverything(mapStateToProps, mapDispatchToProps, mergeProps, state, ownProps);

    return component;
  },

};

src\mockData\defaultState.js

import * as R from 'ramda';

// This is the same object you pass to `combineReducers`.
import { reducersMap } from '../reducers.index';

// Execute each reducer, passing an undefined state to get back their initial state.
const defaultState = R.map((reducer) => reducer(undefined, {}), reducersMap);

export { defaultState };

src\MyComponent\component.test.js

import React from 'react';
import renderer from 'react-test-renderer';

import { defaultState } from '../mockData';

import MyComponent from './component';

// Pass in the default Redux state, along with any specific props you want to mock.
const mockProps = DevPanel.getMappedProps(defaultState, {
  someProp: 'foo',
});

it('renders as expected', () => {
  const component = renderer.create(<MyComponent {...mockProps} />);
  expect(component.toJSON()).toMatchSnapshot();
});