Extend gemspec pattern matching

[jonabc]

Found a few issues with parsing the license field out of a gemspec.

1. The gem specification allows for a licenses array field that wasn't found and captured.
2. The pattern didn't match on frozen strings, e.g. "mit".freeze

Ruby allows regex's to be interpolated inside other regex's which makes the array regex much easier to understand and work with. It also made it simpler to ensure values were treated equally among all of the regular expressions.

The only captured group in these regex's is the license text. All other groups are non-capturing with (?: ...). Meaning in an array like ["mit", "bsd-3-clause"], match[1] == "mit" and match[2] == "bsd-3-clause"

Only the first array value is used, to match current functionality.

[mlinksva]

If there are multiple values in a licenses array I suspect the best match for current functionality would be to return other. That's what licensee does when it encounters multiple licenses, whether from different (eg README and license file) or the same matchers, eg when it finds a license expression in npm packages (though it doesn't attempt to parse out the multiple licenses).

[benbalter]

Ideally, we'd abstract things such that a project file could have multiple licenses, but for now, I agree with @mlinksva that "other" would be the consistent response here (but I'd leave the other logic intact to allow for that). Perhaps expose a matches method for now (in addition to match)?

[jonabc]

I avoided adding any new fields at a broad scope because I wasn't sure how they would be used. It definitely seems worth thinking about for the future.

[jonabc]

@benbalter @mlinksva thanks for taking a look! I've updated per feedback, though I'm not sure why the dependency-ci job failed 🙁

[benbalter]

I'm not sure why the dependency-ci job failed

Probably just added that to test the service. No idea. Safe to ignore.

[benbalter]

👾