Add more documentation on auto-mocking

[Morikko]

🚀 Feature Proposal

Add more documentation on what auto-mocking do, especially for jest.genMockFromModule.
The purpose is to say how each type is transformed by Jest.

Motivation

You have to test the mocked object to know how each type is transformed by jest.

Example

• Function -> Create a mock function that returns undefined
• Async Function -> Create a mock function (synchronous) that returns undefined
• Object -> Do a deep copy of the object (keep the interface) and mock the sub elements
• Class -> Keep the interface and the type but all the functions are mocked
• Array -> Empty array
• String -> copy
• Number -> copy
• Date -> undefined

I could do the PR, however I would gladly appreciate a review of those assumptions.
Also, if some types are missing, let me know.

[SimenB]

@Morikko sorry about the slow response. Yeah, as far as I know, those assumptions holds true. The logic lives here: https://github.com/facebook/jest/blob/68eb9a232dcbd4ecf85bb1f0bdad5cb850dff81a/packages/jest-mock/src/index.js#L646-L723

A PR adding a test verifying those assertions in addition to the docs would be greatly appreciated 🙂

[mackness]

Hi @Morikko and @SimenB if you guys think this still needs to be worked on I would not mind picking it up.

[jeysal]

@mackness the documentation on this is still not very detailed, so I think some improvements would be great :)

[Morikko]

For sure, you can take it :) Le ven. 8 mars 2019 à 00:31, Tim Seckinger <notifications@github.com> a écrit :

…

@mackness <https://github.com/mackness> the documentation on this <https://jestjs.io/docs/en/jest-object.html#jestgenmockfrommodulemodulename> is still not very detailed, so I think some improvements would be great :) — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#6812 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AHeAFPt2_LvHRyIqPbl8tjWckHkl50vyks5vUaFIgaJpZM4Vx1iV> .

[mackness]

I created a PR and I think I'm on the right track but any feedback is greatly appreciated. Definitely open to making improvements. Thanks!

#8099

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