Comparison-test C and Python versions of various modules

[pganssle]

The datetime module has an implementation both in C and in Python, and PEP 399 says that the tests must pass for both versions.

In CPython, some tricksy import magic is done to run the tests with and without the C extension. I don't really love it and I think it might actually be a bit fragile. We can always copy that solution, but I'm opening this ticket to brainstorm or just to put "we should consider other ways to accomplish this" on the to-do list.

[pschanely]

I cannot say how happy I am that you pointed this out to me. Datetime support is in the works!

[Zac-HD]

@pganssle points out here that

If test.support.import_fresh_module were less touchy, I'd be all over this for datetime, and this whole class of tests is super useful for anything with both a C and Python implementation, for PEP 399 compliance. That includes, I believe, heapq, json and warnings, plus any new modules that have a C extension.

So fixing that and then writing the relevant tests seems like a useful thing to have on an issue tracker 😉