Add --format github option

[r7kamura]

How about adding reek --format github CLI option, like rubocop --format github or brakeman --format github?

This would make it very convenient for users in GitHub Actions, as they would be able to see violations on pull request diff page and GitHub Checks page.

[mvz]

@r7kamura I'm not familiar with this GitHub feature. Do you have any background info?

[r7kamura]

In GitHub Actions, when a message of the following form is written to standard output, GitHub will recognize it as a single warning annotation. (some parameters are optional; I chose warning this time, but maybe error would be better)

::warning file={name},line={line},endLine={endLine},title={title}::{message}

Detailed documentation can be found at:

• https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/workflow-commands-for-github-actions

The presence of this annotation will automatically annotate the diff page of the associated pull request; in the case of reek, this means that when the offending code is added, the details of the violation will be annotated there.

Here is an example of this in action:

• https://github.com/r7kamura/reek_github_format_example/pull/1/files
• https://github.com/r7kamura/reek_github_format_example/actions/runs/11551416639

Screenshots:

[mvz]

Thanks @r7kamura, that looks really useful! @troessner WDYT?

[troessner]

Pretty cool, didn't know about this as well, PR looks good to me! LGTM @mvz ?

[mvz]