assert.Regexp: Document allowed rx argument values #268

[brackendawson]

Reference: Antonboom/testifylint#81 (comment)

The Regexp and NotRegexp assertions accept interface{} for the rx (expression) argument. This is insane but we can't change it because it would be a breaking change. The documentation for these functions should be changed to explain that the value should be a *regexp.Regexp, but that if any other type is provided then the %v format of the value will be compiled as a new expression.

[dolmen]

The Regexp and NotRegexp assertion accept interface{} for the rx (expression) argument. This is insane but we can't change it because it would be a breaking change.

💯

The documentation for these functions should be changed to explain that the value should be a *regexp.Regexp, but that if any other type is provided then the %v format of the value will be compiled as a new expression.

I disagree. The arguments haven't been strictly checked from the start, but that doesn't mean we should continue that way and accept any sh@t provided by the user. At least, we must not encourage more sh@t by telling users this is ok via documentation.

The example shown in our documentation already shows usage with *regexp.Regexp and string. I think this is enough.

Also I think that user should give a string, rather than *regexp.Regexp for readability. That's what testifylint currently enforces, and I 💯 agree with that: https://github.com/Antonboom/testifylint#regexp

I'm also encouraging the regexp rule of testifylint to be more strict. See Antonboom/testifylint#292.