Multiple calls mocks. - Githubissues

nrxus / faux

Struct mocking library for Rust

https://nrxus.github.io/faux/

MIT License

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Multiple calls mocks. #2

Closed nrxus closed 4 years ago

nrxus commented 4 years ago

Currently when we set up a mock:

unsafe { when!(my_mock.some_method).then(|_| { /* do things */} )

It sets up a one time mock, which means that after the mock is invoked, next time it runs the code will panic saying that no mock was set.

This library should support mocks that are set up once and run multiple times, either a set number of times, or forever.

nrxus commented 4 years ago

Calling a mock multiple times can be achieved by either:

Having the closure implement clone, which means that any captured data must also implement clone.
Moving away from FnOnce and towards FnMut. This means that any captured data could at most be mutably borrowed and not moved.

I am unsure which one of these two approaches is the most limiting to an user.

nrxus commented 4 years ago

Another thing to keep in mind, do we want to keep the FnOnce without clone behavior for the edge cases where the mock needs to move data that cannot be cloned? Or should that just be removed until I come across an scenario that actually needs that kind of mock

TedDriggs commented 4 years ago

Could you add a new method, .always(...) which had the Clone constraint?

nrxus commented 4 years ago

Yes, that's a possibility.

The biggest two things stopping me from implementing this are:

I haven't run into a use case for this yet in my personal projects so I don't know what the API should be like. Also with faux being pretty new there aren't enough users for me to try and get a feel of what users of faux would want.
I am unsure how clone (or FnMut) mocks should interact with the one time mocks. Should one override the other, just do a latest first, should they both co-exist somehow....? All this uncertainty has stopped me from implementing it.

At some point even without feedback I will move on and just do whatever feels right at the moment but for now I am trying to see if something comes up that guides my decision.

TedDriggs commented 4 years ago

I'd suggest that an active when mock overrules a standing always mock.

audunhalland commented 4 years ago

+1 for multiple calls. Currently cannot switch to faux exclusively because of this.

nrxus commented 4 years ago

I am prioritizing this as my next thing to tackle after https://github.com/nrxus/faux/issues/10

nrxus commented 4 years ago

fixed in: https://github.com/nrxus/faux/commit/a2fc133fa0a2079feef8a42cc4bbea564a51c0b0

I will close this after doing a new release... which should be soon.

nrxus commented 4 years ago

v0.0.4 is released with this feature :tada: