this is a hacky to make ioredis-mock work well with pubsub - related to https://github.com/stipsan/ioredis-mock/issues/773

ioredis-mock-pubsub.ts

jest.mock('ioredis', () => {
  const Redis = require('ioredis-mock');

  if (typeof Redis === 'object') {
    // the first mock is an ioredis shim because ioredis-mock depends on it
    // https://github.com/stipsan/ioredis-mock/blob/master/src/index.js#L101-L111
    return {
      Command: { _transformer: { argument: {}, reply: {} } },
    };
  }

  let instance = null;

  // second mock for our code
  return function (...args) {
    if (instance) {
      return instance.createConnectedClient();
    }

    instance = new Redis(args);

    return instance;
  };
});