A comprehensive test suite would be a valuable tool to have, especially when evaluating all of the variant parsers out there. Does such a beast exist?
In a perfect world, I imagine it would have different sections for different versions of the YAML spec...
There is currently one in the making, see here.
We also generate a result matrix for YAML implementations which
Full disclosure: I am the author of NimYAML and some of the test cases and adapters.