Jest Cheat Sheet

JestCheatSheet.js

// package.json
{
  ...
  "scripts": {
    "test": "NODE_ENV=test jest --ci --verbose",
  },
  ...
  "devDependencies": {
    "@types/jest": "^26.0.3",
    "babel-jest": "^26.1.0",
    "moq.ts": "^6.4.0",
    "jest": "^26.1.0",
  },
  ...
}

// jest.config.js
const { defaults } = require('jest-config')

module.exports = {
  collectCoverage: true,
  collectCoverageFrom: [
    'src/*.{js,ts}',
    '!**/node_modules/**'
  ],
  coverageReporters: [
    'text',
    'cobertura',
    'html'
  ],
  moduleFileExtensions: [
    ...defaults.moduleFileExtensions,
    'ts',
    'tsx'
  ],
  moduleNameMapper: {
    '@src/(.*)': '<rootDir>/src/$1',
    '@tests/(.*)': '<rootDir>/tests/$1'
  }
}
    
// example.test.js
import { Mock } from 'moq.ts'

describe('who tests the tests?', () => {
  it('can run a test', async () => {
    expect.hasAssertions()
    const result = // test something
    expect(result.input).toBe('TESTED')
  })
})