feat(cheatcodes): add vm.expectMockCall to enforce that a mocked function is called with certain arguments

[JasoonS]

Component

Forge

Describe the feature you would like

Currently tests don't break if a mocked function is called with different arguments to what was expected.

Currently for example:

    cheats.mockCall(
      address(mocker),
      abi.encodeWithSelector(
        SomeContract.someFunction.selector,
        5
      ),
      abi.encode(6)
    );

With the above code it will return 6 if the function is called with an argument of 5 or anything else, additionally it won't fail if it isn't called with 5 (which is something you sometimes want to check.

I propose adding a function called something like mockCallStrict to the cheats so that tests can be more strict about this.

Additional context

This is a feature of Smock: https://smock.readthedocs.io/en/latest/fakes.html#asserting-call-arguments

[onbjerg]

You might be interested in expectCall instead. I don't think mockCall should be a superset of expectCall. Sometimes you definitely do want to only mock for a certain parameter, but still retain the ability to get real data for all other cases. If you want a stricter version perhaps this is a good addition to Forge Std instead as a wrapper around expectCall + mockCall

[gakonst]

adding a mock+expect combination in forge-std makes sense to me

[JasoonS]

Thanks, that makes sense to me too.

I won't make any changes to the std lib right now, but I'm working on some code-gen stuff that might be useful for others once it is done to assist with mocking.
Maybe that can be upstreamed at some point if it is useful.

[JasoonS]

Also FYI - my codegen work will allow mocking of internal functions without needing to move the the REVM as mentioned in this PR - #432 .

Like I say, I'll definitely share my work on that in the coming weeks/months 👍

[onbjerg]

@brockelmore Perhaps we should transfer this to Forge Std as well? Or maybe just close it and open up a new issue? Wdyt?

[mds1]

Per #3782, I'm going to move this back to the foundry repo

I'm also not too clear on the exact proposal here, I'd be curious to see sample code of that the cheat/UX would look like