Consider using the commonmark test suite

[kikito]

I don't know how maintained this project is, or if it's even desirable, but I think it would be cool if the test suite used was the commonmark test suite:

https://github.com/commonmark/CommonMark/blob/master/spec.txt

The spec itself is a test suite, and it can be run by doing a simple parsing:

https://github.com/commonmark/CommonMark/blob/master/test/spec_tests.py#L90-L119

I know that there are some other projects that just provide Lua bindings for the Commonmark C library, but I think a pure-Lua implementation has its own benefits.