Testing

[harpocrates]

Here are some approaches to testing correctness of parsing and pretty printing

• Hand written unit test
• Use the unstable nightly -Z option for outputting a JSON of the AST, parse that JSON into our AST and diff them against the AST we get from regular parsing.
• Parse, pretty print, re-parse it, and check that the two ASTs match.
• Re-parse spanned sub-elements from the substring of the input, and check that the two ASTs match.