Mock dependency in jest with typescript

Question

When testing a module that has a dependency in a different file. When assigning that module to be jest.Mock typescript gives an error that the method mock

Answer 1

Here's what I did with jest@24.8.0 and ts-jest@24.0.2:

source:

class OAuth {

  static isLogIn() {
    // return true/false;
  }

  static getOAuthService() {
    // ...
  }
}

test:

import { OAuth } from '../src/to/the/OAuth'

jest.mock('../src/utils/OAuth', () => ({
  OAuth: class {
    public static getOAuthService() {
      return {
        getAuthorizationUrl() {
          return '';
        }
      };
    }
  }
}));

describe('createMeeting', () => {
  test('should call conferenceLoginBuild when not login', () => {
    OAuth.isLogIn = jest.fn().mockImplementationOnce(() => {
      return false;
    });

    // Other tests
  });
});

This is how to mock a non-default class and it's static methods:

jest.mock('../src/to/the/OAuth', () => ({
  OAuth: class {
    public static getOAuthService() {
      return {
        getAuthorizationUrl() {
          return '';
        }
      };
    }
  }
}));

Here should be some type conversion from the type of your class to jest.MockedClass or something like that. But it always ends up with errors. So I just used it directly, and it worked.

test('Some test', () => {
  OAuth.isLogIn = jest.fn().mockImplementationOnce(() => {
    return false;
  });
});

But, if it's a function, you can mock it and do the type conversation.

jest.mock('../src/to/the/Conference', () => ({
  conferenceSuccessDataBuild: jest.fn(),
  conferenceLoginBuild: jest.fn()
}));
const mockedConferenceLoginBuild = conferenceLoginBuild as 
jest.MockedFunction<
  typeof conferenceLoginBuild
>;
const mockedConferenceSuccessDataBuild = conferenceSuccessDataBuild as 
jest.MockedFunction<
  typeof conferenceSuccessDataBuild
>;