Version: Next

Mock ES6 class

TypeScript is transpiling your ts file and your module is likely being imported using ES2015s import. const soundPlayer = require('./sound-player'). Therefore creating an instance of the class that was exported as a default will look like this: new soundPlayer.default(). However if you are mocking the class as suggested by the documentation.

JavaScript
TypeScript

jest.mock('./sound-player', () => {
  return jest.fn().mockImplementation(() => {
    return { playSoundFile: mockPlaySoundFile }
  })
})

jest.mock('./sound-player', () => {
  return jest.fn().mockImplementation(() => {
    return { playSoundFile: mockPlaySoundFile }
  })
})

You will get the error

TypeError: sound_player_1.default is not a constructor

because soundPlayer.default does not point to a function. Your mock has to return an object which has a property default that points to a function.

JavaScript
TypeScript

jest.mock('./sound-player', () => {
  return {
    default: jest.fn().mockImplementation(() => {
      return {
        playSoundFile: mockPlaySoundFile,
      }
    }),
  }
})

jest.mock('./sound-player', () => {
  return {
    default: jest.fn().mockImplementation(() => {
      return {
        playSoundFile: mockPlaySoundFile,
      }
    }),
  }
})

For named imports, like import { OAuth2 } from './oauth', replace default with imported module name, OAuth2 in this example:

JavaScript
TypeScript

jest.mock('./oauth', () => {
    return {
        OAuth2: ... // mock here
    }
})

jest.mock('./oauth', () => {
    return {
        OAuth2: ... // mock here
    }
})