Mocking Date.Now jest toHaveBeenCalledWith in nestJs - node.js

Question

I am trying to figure out how to mock a call to Date.now with jest in my nestjs application.
I have a repository method that soft deletes a resource
async destroy(uuid: string): Promise<boolean> {
await this.userRepository.update({ userUUID: uuid }, { deletedDate: Date.now() });
return true;
}
to soft delete we just add a timestamp of when it was requested to be deleted
Following some discussions on here and other sites I came up with this test.
describe('destroy', () => {
it('should delete a user schemas in the user data store', async () => {
const getNow = () => Date.now();
jest
.spyOn(global.Date, 'now')
.mockImplementationOnce(() =>
Date.now().valueOf()
);
const targetResource = 'some-uuid';
const result = await service.destroy(targetResource);
expect(result).toBeTruthy();
expect(userRepositoryMock.update).toHaveBeenCalledWith({ userUUID: targetResource }, { deletedDate: getNow() });
});
});
I assumed that .spyOn(global.Date) mocked the entire global dat function , but the Date.now() in my repository is still returning the actual date rather than the mock.
My question is, is there a way to provide the mock return value of Date.now called in the repository from the test or should I just DI inject a DateProvider to the repository class which I can then mock from my test?

Answer 1

jest.spyOn(Date, 'now') should work.
E.g.
userService.ts:
import UserRepository from './userRepository';
class UserService {
private userRepository: UserRepository;
constructor(userRepository: UserRepository) {
this.userRepository = userRepository;
}
public async destroy(uuid: string): Promise<boolean> {
await this.userRepository.update({ userUUID: uuid }, { deletedDate: Date.now() });
return true;
}
}
export default UserService;
userRepository.ts:
class UserRepository {
public async update(where, updater) {
return 'real update';
}
}
export default UserRepository;
userService.test.ts:
import UserService from './userService';
describe('60204284', () => {
describe('#UserService', () => {
describe('#destroy', () => {
it('should soft delete user', async () => {
const mUserRepository = { update: jest.fn() };
const userService = new UserService(mUserRepository);
jest.spyOn(Date, 'now').mockReturnValueOnce(1000);
const actual = await userService.destroy('uuid-xxx');
expect(actual).toBeTruthy();
expect(mUserRepository.update).toBeCalledWith({ userUUID: 'uuid-xxx' }, { deletedDate: 1000 });
});
});
});
});
Unit test results with 100% coverage:
PASS stackoverflow/60204284/userService.test.ts
60204284
#UserService
#destroy
✓ should soft delete user (9ms)
----------------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------------|---------|----------|---------|---------|-------------------
All files | 100 | 100 | 100 | 100 |
userService.ts | 100 | 100 | 100 | 100 |
----------------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 5.572s, estimated 11s
source code: https://github.com/mrdulin/react-apollo-graphql-starter-kit/tree/master/stackoverflow/60204284