Claude wrote the harness and pretty much all of these tests, eg:

https://github.com/williamcotton/search-input-query/blob/mai...

It is a good test suite and it saved me quite a bit of typing!

In fact, Claude did most of the typing for the entire project:

https://github.com/williamcotton/search-input-query

BTW, I obviously didn't just type "make a lexer and multi-pass parser that returns multiple errors and then make a single-line instance of a Monaco editor with error reporting, type checking, syntax highlighting and tab completion".

I put it together piece-by-piece and with detailed architectural guidance.