@jetshop/core/experiments/ExperimentsProvider.test.js

import React, { useContext } from 'react';
import { render, cleanup } from '@testing-library/react';
import { StaticRouter } from 'react-router';
import { CookiesProvider } from 'react-cookie';
import Cookies from 'universal-cookie';
import ExperimentsProvider, { ExperimentsContext } from './ExperimentsProvider';
import AnalyticsProvider from '../analytics/AnalyticsProvider';
import { ConfigProvider } from '../components/ConfigProvider';
import { ChannelProvider } from '../components/ChannelContext';
import { ChannelHandler } from '../ChannelHandler/ChannelHandler';
import { selectedChannel, channels } from '../test-utils/variables';
import { HelmetProvider } from 'react-helmet-async';

afterEach(cleanup);

const Collector = ({ fn }) => {
  const value = useContext(ExperimentsContext);
  fn(value);
  return null;
};

const setup = ({ cookies, shopConfig = {} }) => {
  let data;
  const channelHandler = new ChannelHandler({
    selectedChannel,
    channels
  });

  render(
    <StaticRouter>
      <CookiesProvider cookies={cookies}>
        <HelmetProvider context={{}}>
          <ChannelProvider channelHandler={channelHandler}>
            <ConfigProvider config={shopConfig}>
              <AnalyticsProvider config={{}}>
                <ExperimentsProvider>
                  <Collector fn={value => (data = value)} />
                </ExperimentsProvider>
              </AnalyticsProvider>
            </ConfigProvider>
          </ChannelProvider>
        </HelmetProvider>
      </CookiesProvider>
    </StaticRouter>
  );

  return {
    data
  };
};

describe('ExperimentsProvider', () => {
  it('reads the current experiment and value from the optimizeExperiment cookie', () => {
    const cookies = new Cookies({
      optimizeExperiment: 'test.0'
    });

    const { data } = setup({ cookies });

    expect(data.experiment).toBe('test');
    expect(data.variant).toBe(0);
  });

  it('defaults the values to null if no cookie was set', () => {
    const { data } = setup({ cookies: new Cookies({}) });
    expect(data.experiment).toBe(null);
    expect(data.variant).toBe(null);
  });

  it('runs the trackExperiment function when mounting', () => {
    const trackExperiment = jest.fn();

    const cookies = new Cookies({
      optimizeExperiment: 'test.0'
    });

    const shopConfig = {
      trackers: [
        {
          name: 'test',
          trackExperiment
        }
      ]
    };

    setup({ cookies, shopConfig });

    expect(trackExperiment).toHaveBeenCalledTimes(1);
    expect(trackExperiment).toHaveBeenCalledWith(
      {
        id: 'test',
        variant: 0
      },
      expect.anything()
    );
  });
});