Mocking a Database in Node with Jest 

Agreed

Also, is that your campus??

Yes it is. Completely empty right now so not bad for filming 🤗

Exactly, this seems to only work if all logic; routes, controllers, services/business logic are in one file and Db calls all happen directly inside the createApp function. Would be useful to know how to mock the data access layer for a layered architecture.

bit of a late reply but if you have separate router files, turn them into static classes that get exported. that way, app.js can send your database into the classes via a static function in each class to get the router and set the database, the classes save them as static properties, and now you got routers in separate files all using the database passed into app.js. Hope that helps.

It isn't connected to the database. Jest.fn() can 'mock' a database call. For example, if your database query returned `{username: "chilly21"}` when a request was sent to it with `{userId: 1}`, then you could simulate this with Jest.fn(({userId})=> return {username:"chilly21"}). The idea is that you completely remove the connection to your database so that it speeds up your testing and so that your database is preserved. The Jest.fn() function allows you to simulate a database call and also gives you lots of other features, such as allowing you to test number of times called (eg `expect(mockCallback.mock.calls.length).toBe(2);`).

You’re welcome 😊

I agree, I don't do that anymore

Toby Tranter - Memories Don't Lie