Switch over to GitHub Actions and fix various issues with the test suite

[judofyr]

This is in order to prepare a new release.

@ntkme: Could you have a look at this and see if it makes sense?

Pending work to make all tests work:

• Workaround this JRuby bug: Line number is incorrect for interpolation inside heredoc jruby/jruby#7272
• Figure out why RDiscount doesn't support smart settings in the CI: https://github.com/rtomayko/tilt/runs/7396767676?check_suite_focus=true. This passes locally on my Mac.

[ntkme]

LGTM except the two issues you already found. I will do some test for RDiscount in my environment and see if I can reproduce it.

[ntkme]

@judofyr Seems like there is a weird conflict between loading bluecloth and rdiscount. - If you try to add a require 'rdiscount' anywhere before require 'bluecloth', the rdiscount test will pass and the bluecloth test now fails. At quick test shows, whoever gets loads first between the two wins, but I haven't got a chance to look at exactly why.

[ntkme]

The issue is that both bluecloth and rdiscount are bundling a native extension for discount. bluecloth bundles 2.0.6 but rdiscount bundles 2.2.0. I think the best way to deal with it is to isolate the two from being tested together.

[judofyr]

@judofyr Seems like there is a weird conflict between loading bluecloth and rdiscount. - If you try to add a require 'rdiscount' anywhere before require 'bluecloth', the rdiscount test will pass and the bluecloth test now fails. At quick test shows, whoever gets loads first between the two wins, but I haven't got a chance to look at exactly why.

Oh wow! What a great find. I've seen this errors for years and never understood the reason for it. I think the most sensible thing is to not test for BlueCloth. It's a very old package anyway and not actively maintained.

[judofyr]

Alrighty, @ntkme, I think I've fixed all the problems now! Looks good?

[ntkme]

LGTM!