Using the queue manager in external TypeScript projects

Using the queue manager in external TypeScript projects is slightly difficult as TypeScript does not know of the type for the global variable queueManager. Additionally, using the interface functions will make the tests fail as the global is not defined.

Solving the first issue is relatively straight forward as we need to declare the variable so TypeScript knows of it. First install the package @keneanung/nexus-queue-manager (i.e. through a terminal):

npm install @keneanung/nexus-queue-manager

Then add the following to the top of the src/index.ts file:

import { IQueueManager } from "@keneanung/nexus-queue-manager";

declare global {
  // eslint-disable-next-line no-var
  var queueManager: IQueueManager
};

The eslint-disable-next-line is there to prevent the ESLint rule no-var from complaining about the global variable. But we need to declare it as var to be able to assign it in tests.

To make the tests work, the easiest way would be to install the npm package jest-mock-extended as a development dependency and use it like this:

import { mock } from 'jest-mock-extended';
import { IQueueManager } from '@keneanung/nexus-queue-manager';

globalThis.queueManager = mock<IQueueManager>();

Now, the object exists with all functions implemented as jest.fn()s. Please refer to the Jest documentation on how to test interactions.