Question about your remark on mongo-testing. about testing-nestjs HOT 4 CLOSED

@warreee I never said anything about save as a method. I suggested not using new this.model() because that's what becomes difficult to mock. When you create a new instance of the thing you're mocking, it gets messy. It's the difference of using an Active Record approach (where each instance of a model or entity has its own Data Manipulation Methods) vs a Data Mapper approach (where you use a central service and pass entities and models to it so it can talk with the database).

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Alright, thanks for the clarification.
However, do you have an idea of why I can't do:
jest.spyOn(model, 'save').mockResolvedValueOnce({...});
But I can do:
jest.spyOn(model, 'create').mockResolvedValueOnce({...});

The save method seems not to be able to be spied on, however as in your example tests for create, update, findOne ... this works perfectly fine?
I tried this also in your mongo example so that I was sure it was not my project setup messing with this...

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Yes, because when you do new this.model() (which creates the Document instance that has the save method), you no longer are working with this.model, but the returned object of that. If you look at the types, Model has no method called save.

from testing-nestjs.

I see thanks!

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