Take Python test cases?

[da-woods]

It might be worth taking https://github.com/python/cpython/blob/main/Lib/test/test_string/test_templatelib.py from Python and running it against your own implementation. The linked test is a library-only test so shouldn't require the full t-string syntax.

[NickCrews]

Great idea. When I get to this I will probably just vendor in the whole file into this repo so we continue to have that coverage.