@nklein I don't understand your test. How can [int, string, string] have the same structure as [string, string, int]?

Still is possible to make some shortcuts.

this test is still borked

Yes, I hadn't really anticipated people dumping things to strings. I will update the tests.

You still need to make some updates.

• There's an expectation that an undefined type will return '' from toString, but still parse a value? Nothing about that is in the description.
• Your tests are very frustrating, because you run the example code all at once, but then perform multiple tests at the end. This makes it nearly impossible to debug.
• You are using Test.expect(), which means that there's no way to see what the actual values our code is providing — only the expected result. And, since we can't see the input lined up with the output, it might as well be random data.
• Looking at your "working" code, I have absolutely no idea how to get those results from your description. The part specifically where you are checking the parsed value against the original input is bizarre.

done