How to use GitHubStarButton method in Jest

The Problem is the setImmediate function.

I just added the polyfill.js in my test class : import 'core-js'; after that setImmediate was defined again and works now as intended.

The problem on your expression relies on the first expectation which is

toEqual()

the expectation should use toMatchObject like:

expect(insertedData).toMatchObject({...

I struggled with this for hours/days and only this worked for me:

1) In your test:

Date.now = jest.fn(() => new Date(Date.UTC(2017, 7, 9, 8)).valueOf())

2) Then change the TZ env var before running your tests. So the script in my package.json:

• (Mac & Linux only)

  "test": "TZ=America/New_York react-scripts test --env=jsdom",
  

• (Windows)

  "test": "set TZ=America/New_York && react-scripts test --env=jsdom",
  

I found out that the problem was the rewire lib. For some reason, it was messing with the window's events. I remove it and change my code to be able to mock data variable without rewire

Jest parallelizes test runs and it doesn't know upfront which tests it should run and which it shouldn't run. This means when you use "fit", it will only run one test in that file. But it still runs all other test files in your project.

fit, fdescribe and it.only, describe.only have the same purpose: skip other tests and run only me.

Source: https://github.com/facebook/jest/issues/698#issuecomment-177673281

Use the Jest filtering mechanism. When you run your tests like,

jest --config=jest.config.json --watch

you can filter tests by a testname or filename. Just follow the instructions in the terminal.

Press p, and then type a filename.

Then you can use describe.only and it.only which will skip all other tests from the filtered, tested file.

The problem is not really related to Node caching modules - it's express who stores a reference to a middleware function when a server is initially created. After isAdmin method of required module is stubbed, it's the cached version who gets stubbed, so using a tool like proxyquire would only allow you to require a fresh version of the module (without stubbed method) if you need it for some reason.

If what you're looking for is adjusting behavior of a particular middleware for already created express server, you'd need a way to alter middleware function's behavior by its reference. Hopefully, sinon stubs (and others too, e.g. ones jest provides) are capable of that. However, you still need to stub the module before creating an express server so it stores a reference to the stubbed function.

Sample implementation might look as follows:

const request = require("supertest");
const { expect } = require("chai");
const sinon = require('sinon');
const auth = require ("../utils/auth-middleware");

// store reference to original function in case you need it:
const originalIsAdmin = auth.isAdmin

// replace isAdmin method with a stubbed, but don't specify implementation yet
const adminStub = sinon.stub(auth, "isAdmin");

// init express server that relies on stubbed `auth.isAdmin` reference
const app = require("../app.js");

it('this test is using auth.isAdmin that just calls .next()', () => {
  // make middleware just pass
  auth.isAdmin.callsFake((req, res, next) => next());

  // ...
});

it('this test is using real auth.isAdmin implementation', () => {
  // make middleware call real implementation
  auth.isAdmin.callsFake(originalIsAdmin);

  // ...
});

Presets are just plain Javascript objects, so in many circumstances you may simply merge them. For example, that's how I'm enabling ts-jest and jest-puppeteer simultaneously:

const merge = require('merge')
const ts_preset = require('ts-jest/jest-preset')
const puppeteer_preset = require('jest-puppeteer/jest-preset')

module.exports = merge.recursive(ts_preset, puppeteer_preset, {
    globals: {
        test_url: `http://${process.env.HOST || '127.0.0.1'}:${process.env.PORT || 3000}`,
    },
})

If there are certain options that can't be 'merged' like that, just handle these cases manually.

I can't answer your questions on how to do this with jest mocking, but I hope I can give you some insights here nontheless - from the perspective of having written most of RTKQ and how I imagine it to be tested in a stable way:

I wouldn't use jest mocking. I would mock the API.

The reason for this being is that your mocks will assume certain return values from the RTKQ hook - and if your assumptions are wrong, you might have a nice green running test, but in reality your app will still fail.

An example of this would be using skip and not checking for isUninitialized - since that case will not come up if you are not using skip and you might just assume that you will only ever see isLoading, isSuccess and isError cases in your component. It's a perfectly valid assumption in many cases, but not always true. Mocking RTKQ would hide the resulting bug behind green tests.

Instead, I would recommend using something like mock service worker to just mock your api endpoints and let RTKQ do it's work. That is how we are testing RTKQ ourselved in our own tests - you are welcome to take a look there: RTKQ tests.

This example will work if you compile ES6 modules syntax into ES5, because in the end, all module exports belong to the same object, which can be modified.

import { allowThrough } from './allowThrough';
import { ENABLED } from './constants';
import * as constants from './constants';

describe('allowThrough', () => {
    test('success', () => {
        constants.ENABLED = true;

        expect(ENABLED).toBe(true);
        expect(allowThrough({ value: 1 })).toBe(true);
    });

    test('fail, ENABLED === false', () => {
        constants.ENABLED = false;

        expect(ENABLED).toBe(false);
        expect(allowThrough({ value: 1 })).toBe(false);
    });
});

Alternatively, you can switch to raw commonjs require function, and do it like this with the help of jest.mock(...):

const mockTrue = { ENABLED: true };
const mockFalse = { ENABLED: false };

describe('allowThrough', () => {
    beforeEach(() => {
        jest.resetModules();
    });

    test('success', () => {
        jest.mock('./constants', () => mockTrue)
        const { ENABLED } = require('./constants');
        const { allowThrough } = require('./allowThrough');

        expect(ENABLED).toBe(true);
        expect(allowThrough({ value: 1 })).toBe(true);
    });

    test('fail, ENABLED === false', () => {
        jest.mock('./constants', () => mockFalse)
        const { ENABLED } = require('./constants');
        const { allowThrough } = require('./allowThrough');

        expect(ENABLED).toBe(false);
        expect(allowThrough({ value: 1 })).toBe(false);
    });
});