I've been using a 'golden tests' library for testing my parser, and it's just delightful. Rather than writing a verbose assertion about the resulting AST, I can just re-run my tests until the output looks good!
I'm using https://github.com/jfecher/golden-tests currently, which can automatically update the output in the file.
Example commit: https://github.com/Wilfred/garden/commit/cea75238ff9de0b74caf20c64096c2fa46cdc30a