Document the default behavior of require-error and fn-pattern

[ian-h-chamberlain]

From reading https://github.com/Antonboom/testifylint#require-error it's not immediately clear to me which calls will be flagged. Initially I assumed there was some default regex for fn-pattern and the user could override it by specifying configuration.

However, it looks like there is actually a hardcoded list of function names, and the regex only serves to filter them down further: https://github.com/Antonboom/testifylint/blob/fc4c8235262c71530c5870869ebe8baa4ad44e6a/internal/checkers/require_error.go#L121C6-L121C7

1. Is my understanding of the configuration accurate?
2. If so, would you consider adding some documentation to the README explaining this?

Thanks!

[Antonboom]

Hi!

the user could override it by specifying configuration

exactly so

and the regex only serves to filter them down further

this is right too

in other words – require-error marks any error assertions (how README said), but you could select the specific assertions by fn-pattern

example here:

    require-error:
      # Regexp for assertions to analyze. If defined then only matched assertions will be reported.
      # Default: ""
      fn-pattern: ^(Errorf?|NoErrorf?)$

^ it means require will be required (sorry for tautology 🙂) only for

assert.NoError(t, err)
assert.NoErrorf(t, err, "msg")
assert.Error(t, err)
assert.Errorf(t, err, "msg")

other errors assertions (from hardcoded list) will be skipped.

You could not specify require-error for assertions like Negative or WithinDuration or any other not-error-assertion fn-pattern, because it doesn't make sense.

---

Please provide an example and goal what you want to reach, thanks

[ian-h-chamberlain]

Got it, thanks for explaining in more detail. I think to make it more clear perhaps I'd suggest a change like this:

Also you can configure functions to analyze via --require-error.fn-pattern flag.

into something like

By default, all *Error*-related functions will be checked (e.g. assert.ErrorContains, assert.NoError, assert.ErrorAs).

You can configure --require-error.fn-pattern to limit the check to certain calls, for example:
--require-error.fn-pattern='^(Errorf?|NoErrorf?)$'
would only check Error, Errorf, NoError, and NoErrorf.

I think that would make it more clear that not every assert.* function call will be checked, but just the Error related ones (i.e. the hardcoded list). It probably doesn't make sense to put the entire list in the README but some examples would be helpful, I think.

Thanks again!