Add HeroesComponent example with mocked service provider (#110) #188
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This was causing the linter to complain about existing imports (e.g. in hero service)
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Honestly I'm against this kind of testing. You mock the service, so whenever you break it, test won't catch it 🤷♂️. I usually advice to mock request library/API itself, because that's what your code doesn't have control over – you can however mock request to return anything and check whether your service reacts properly. |
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Yeah for sure, this type of mocking can be dangerous if the service itself is not also tested. This is under the assumption that the service itself is also properly tested (i.e. via HTTP mocks). Ideally the component should not know or care where the service is getting its data from or what format it comes in. By mocking the low-level HTTP responses in the component spec the tests become tightly coupled with dependencies that the component itself does not know exist. This can be especially problematic for services that are used in many places. For example, a small change to an external API could require updates to every spec with the service in its dependency chain. However, if the contract between the app and the external API is solely owned by the respective service then only that single spec would need to be updated and the developers can go fast forever. Another advantage of this style (especially with angular stuff) is that other distant dependencies can be omitted from the spec, which can minimize the required resources and speed up run time. |
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Actually what @ParkerM did is from Angular guide for unit test. I also do the same with my work. What @thymikee suggested wasn't wrong but it's more about integration test between the component and the real service without mocking. So if in the situation of unit test, I'd say mocking like this is ok. But in practical, ofc we need one test to cover the service itself and one more integration test for the component and the service. |
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Yea, I'm a fan of testing integrations not units :D But I don't see a reason we shouldn't merge that, it's just an example :) |
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Can you update this same example to work by automocking a service class ? |
Related to Issue #110
An example of how to mock a service provider's return values using
jest.fn()and rxjs'Subjectwithout having to bother with mocking low-level HTTP responses.I placed the component in its own
heroesfolder which is kind of awkward since the Hero model and service are in the more genericservicefolder, but I didn't want to take too many liberties in moving stuff around.Other small changes:
'rxjs'from the import-blacklist as it was causing linter warnings on existing code.