How to mock the time for Later.JS

Question

I am using Later.JS for a automatic function call every first day of the month. For testing I need to mock the time to check if Later.JS and my code does the right things. Can some one help me how I can mock this past time.

Thank you

Answer 1

What library do you use for unit testing? I like Jest because is very intuitive. It has function mock documented here .

jest.mock(path, moduleFactory) takes a module factory argument. A module factory is a function that returns the mock.

And usage:

jest.mock('laterJS', () => () => ({format: () => '2018–01–30T12:34:56+00:00'}));

Check also jest.spyOn documented here .

Last, but not least, there is sinonJS and its stubs , great tool for mocking functions and libraries and using your own implementation of function for testing purpose like returning hard-coded timestamp. Here it is .

EDIT: After editing question I understood what OP want to achieve

Alright, by unclear question I thought you were interesting in testing your code, now I'm aware you want to test both: laterJS schedule and your code.

Basically, all crones / schedulers are created for running code / tasks every some period of time. Under the hood, in very simplified way, scheduler is all the time checking if any of schedule conditions are met. If yes - do something. To achieve it you have mock clock to make laterJS to think that's a time to run his job.

I have no experience with laterJS, I have some with node-cron, but the idea is exactly the same. Check some of their test suites to realise what approach is proper one.