Testing

Testing

Jest

Config

Покрытие с одного файла

The solution is to add one small option --collectCoverageFrom
 to collect only for a certain file (i.e. component).

yarn test my-component.test 
	--coverage 
	--collectCoverageFrom=src/components/my-component/my-component.tsx

Падать на упавших тестах

// jest.config.js
module.exports = {  
  // stop after first failing test
  bail: true

  // stop after 3 failed tests
  bail: 3
}

Запуск по названию теста

Использовать флаг --testNamePattern или -t :

jest -t 'fix-order-test'

Mock

Reset mocks

  beforeEach(() => {
    jest.resetAllMocks();
  });

Mock only one function from module

jest.mock('./utilities.js', () => ({
  ...jest.requireActual('./utilities.js'),
  speak: jest.fn(),
}));

jest.mock("react", () => ({
  ...jest.requireActual("react"), // import and retain the original functionalities
  useContext: jest.fn().mockReturnValue({foo: 'bar'}) // overwrite useContext
}))

For packages:

import axios from 'axios';

jest.spyOn(axios, 'get');
axios.get.mockImplementation(() => { /* do thing */ });

Mock default module

import dependency from 'dependency'

jest.mock('dependency', () => ({
  ...jest.requireActual('dependency'),
  __esModule: true,
  default: jest.fn(),
}))

Expect()

Expect async function to throw

it('should test async errors', async () =>  {        
    await expect(failingAsyncTest())
    .rejects
    .toThrow('I should fail');
});

Custom Error Class:

it("should test async errors", async () => {
  await expect(asyncFunctionWithCustomError())
	  .rejects
	  .toBeInstanceOf(CustomError)
})

Ariakit Test Utils

https://twitter.com/ericclemmons/status/1573409650371973120?t=WYDGjaNLIqohX200TGt3Uw&s=19