jest-launchdarkly-mock

jest-launchdarkly-mock

Easily unit test LaunchDarkly feature flagged components with jest :clap:

This package is only compatible with the react sdk.

Installation

yarn add -D jest-launchdarkly-mock

or

npm install jest-launchdarkly-mock --save-dev

Then in jest.config.js add jest-launchdarkly-mock to setupFiles:

// jest.config.js
module.exports = {
  setupFiles: ['jest-launchdarkly-mock'],
}

Usage

Use the only 3 apis for test cases:

• mockFlags(flags: LDFlagSet): mock flags at the start of each test case. Only mocks flags returned by the useFlags hook.

• ldClientMock: a jest mock of the ldClient. All methods of this object are jest mocks.

• resetLDMocks : resets both mockFlags and ldClientMock.

Example

import { mockFlags, ldClientMock, resetLDMocks } from 'jest-launchdarkly-mock'

describe('button', () => {
  beforeEach(() => {
    // reset before each test case
    resetLDMocks()
  })

  test('flag on', () => {
      // arrange
      // You can use the original unchanged case, kebab-case, camelCase or snake_case keys.
      mockFlags({ devTestFlag: true })
  
      // act
      const { getByTestId } = render(<Button />)

      // assert
      expect(getByTestId('test-button')).toBeTruthy()
    })

  test('identify', () => {
    // arrange
    mockFlags({ 'dev-test-flag': true })
    
    // act
    const { getByTestId } = render(<Button />)
    fireEvent.click(getByTestId('test-button'))

    // assert: identify gets called
    expect(ldClientMock.identify).toBeCalledWith({ key: 'aa0ceb' })
  })
})

Changelog

[2.1.0] - 2023-06-06

Changed:

• useFlags now returns an empty object by default, which matches its actual implementation.