Add feature to generate JUnit XML output

[jcoleman]

Background

It's common to use the JUnit plugin on Jenkins to consume machine-readable output about the tests in your CI builds. For example, on our Ruby app tests we use the rspec_junit_formatter to output results from RSpec in a format that Jenkins can consume.

What

This PR adds JUnit style XML output as an option to Spoom so that running Sorbet in CI on Jenkins can output error information that can be displayed natively by Jenkins (and then, in turn, passed along to e.g. Github's interface).

With these changes Sorbet failures on a build look like this:

and a clean Sorbet build looks like this:

TODO

I'm happy to add docs for this feature as well, but I wanted to get initial review of the feature going sooner rather than later.

[Morriar]

Hey @jcoleman,

I think the feature is okay but the code will need to be adjusted.

Thanks!

[jcoleman]

@Morriar I think I've responded to all of your feedback; I usually leave clicking "Resolve" for the reviewer so they can confirm the change first; let me know if you have a different preference.

[jcoleman]

@Morriar Would you be able to trigger workflows and re-review?

[jcoleman]

@Morriar I think all of your feedback is resolved now, and I've rebased on main.

[Morriar]

Tests are failing because we're missing the type signatures.

[jcoleman]

@Morriar Pushed up final changes (weird double commit since I used the Github review "commit suggestions" feature for the first bit, and then had to manually push up another bit separately).

[Morriar]

This looks good, thanks!

[jcoleman]

Some style issues I'll fix in a minute:

Offenses:

lib/spoom/sorbet/errors.rb:209:13: C: [Correctable] Style/TrailingCommaInArrayLiteral: Put a comma after the last item of a multiline array.
            *more
            ^^^^^
spoom.gemspec:40:3: C: [Correctable] Gemspec/OrderedDependencies: Dependencies should be sorted in an alphabetical order within their section of the gemspec. Dependency rexml should appear before thor.
  spec.add_dependency("rexml", ">= 3.2.6")
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
test/spoom/cli/srb/tc_test.rb:383:19: C: [Correctable] Style/RegexpLiteral: Use %r around regular expression.
            .gsub(/^(\s+)https:\/\/github\.com\/sorbet\/sorbet\/tree\/[0-9a-f]+/, '\1<GIT_LINK>')
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[jcoleman]

@Morriar I think you'll have to approve the workflow again for the Rubocop fixes.

[jcoleman]

@Morriar I fixed the generated RBI files now (it's unfortunate that CI doesn't run all the checks but only proceeds if the previous step completes 😞).

[Morriar]

For some reason CI is not triggering, can you try rebasing on main and pushing again?