I can't make an issue, so I'll ask here: if I follow the link at the end of README.md, I end up in the pull requests. I don't see the issues tab for this project for some reason.

Hi - I'm sorry for the silence on this PR, somehow I missed the notification

• Your code change looks good - nice work! To be honest, I've not looked too deeply into how the test suite for this plugin was set up by shopkeep - I just needed a released version with a couple of PRs merged for my own use - but from a brief look the test seems reasonable
• I think GitHub automatically disabled issues on forks, I'm guessing that this is to push people to open issues in the original repo rather than the fork. I'm going to leave it disabled for now, so that users of the original pytest-black have visibility on issues that affect them, and so that Shopkeep get a better idea of how people are using their code - perhaps they will pick up maintenance again at some point. If this pytest-black-ng drifts far enough away from pytest-black that there are issues that only impact users for -ng, then I'll enabled the issue tracker

As for this PR, although the code looks reasonable I'm a little confused as to why it is required in the first place. The point of Black is that it is applied universally and automatically - typically by a post-save hook in your editor. From the comments on the original PR, it sounds like the intended use for this is to be able to run test over code that hasn't been processed by Black. I can't really think of a situation where you would want this - can you provide an example of the kind of use case that you have for this functionality?

Apologies again for the delay in looking at this.

- Will