Allow running specific test with `path/to/test.rb:loc`

[phillipspc]

Sometimes you just want to run a single test. Minitest and RSpec both support this, and I think it would be a good addition to Quickdraw! 🤠

[joeldrapper]

I’m working on a really big change in the design first but I do plan to support this.

[kaspth]

Technically, minitest doesn't support running tests by line number, but it does support filtering tests on name:

   -n, --name PATTERN               Filter run on /regexp/ or string.
   -e, --exclude PATTERN            Exclude /regexp/ or string from run.

I often do bin/rails t -n /some_method/ to run my tests.

Now, Rails supports line filtering out of the box, but it's implemented via the above pattern support in minitest. When minitest loads, it populates the --name filter into a filter: option and calls === on it.

Rails overrides the passed in filter: with a custom CompositeFilter that also responds to ===.
That happens here https://github.com/rails/rails/blob/5813c82bbd3770d15f8b7f22e898727a7587f6df/railties/lib/rails/test_unit/line_filtering.rb#L8

It looks like the code itself has gotten quite a bit more complex since I wrote it, but the essential logic is in CompositeFilter#=== here https://github.com/rails/rails/blob/5813c82bbd3770d15f8b7f22e898727a7587f6df/railties/lib/rails/test_unit/runner.rb#L158
We then defer to each custom filter's === method here, to blend Rails filters by file/line and minitest's regex filters. https://github.com/rails/rails/blob/5813c82bbd3770d15f8b7f22e898727a7587f6df/railties/lib/rails/test_unit/runner.rb#L194-L201

[kaspth]

minitest's rationale for test name based filtering is that the name is less likely to change versus the line number. That's not always the case though, and sometimes line number filtering is handy. I do prefer minitest's -n // regexes almost always.

I'm not saying Quickdraw needs to support this, I just like this kind of code archeology 😄 — even if we may want to revisit things from scratch.