yasu-s / jest-clock-patch

Jest clock patch sample

Overview

• This is a sample extension for using jasmine.clock().mockDate() with Jest.
• This is done using MockDate.
• Values such as Date.now(), new Date(), and moment() are overwritten by MockDate.

System requirements

• Node.js - 10.x
• Yarn - 1.12.x

Used library

• Jest - 24.9.x
• ts-jest - 24.0.x
• TypeScript -3.5.x
• mockdate - 3.5.x

Operation check

1. Download sample

git clone [e-mail]:yasu-s/jest-clock-patch.git

2. Installing packages

cd jest-clock-patch
yarn

3. Launch sample application

yarn test

Sample source

jest.config.js

module.exports = {
  "testEnvironment": "node",
  "verbose": true,
  "moduleFileExtensions": [
    "ts",
    "tsx",
    "js"
  ],
  "transform": {
    "^.+\\.(ts|tsx)$": "ts-jest"
  },
  "globals": {
    "ts-jest": {
      "tsConfig": "tsconfig.json"
    }
  },
  "testMatch": [
    "**/test/*.+(ts|tsx|js)"
  ],
  "resetMocks": true,
  "setupFilesAfterEnv": [
    "./setup-clock-patch.ts"
  ]
};

setup-clock-patch.ts

import * as mockdate from 'mockdate';

// jasmine.clock().mockDate defined
jasmine.clock = () => {
  return {
    mockDate: (date) => {
      mockdate.set(date);
    }
  } as any;
};

beforeEach(() => {
  mockdate.reset();
});

test/data-test.ts

describe('Date', () => {
  it('now', () => {
    // setup
    jasmine.clock().mockDate(new Date(2019, 1, 1));

    // exercise
    const actual = Date.now();

    // verify
    expect(actual).toBe(new Date(2019, 1, 1).valueOf());
  });

  it('new Date()', () => {
    // setup
    jasmine.clock().mockDate(new Date(2019, 2, 1));

    // exercise
    const actual = new Date();

    // verify
    expect(actual.valueOf()).toBe(new Date(2019, 2, 1).valueOf());
  });

  it('mockDate reset check', () => {
    // exercise
    const actual = new Date();

    // verify
    expect(actual.valueOf()).not.toBe(new Date(2019, 2, 1).valueOf());
  });
});

Reference

• Jest - https://jestjs.io/ja/
• MockDate - https://www.npmjs.com/package/mockdate