React to internal test improvements

[CaseyCarter]

• Tell the internal test runner to use expected_results.txt instead of skipped_tests.txt as its control file. (The internal runner has learned to translate the expected_results.txt format to what it needs.)
• Move skips for the two XFAIL: msvc tests from skipped_tests into expected_results. (LIT ignores these, but the internal runner needs them.)
• Remove main from compile-only tests in std; the internal test runner understands compile-only tests now.

This is a dual of MSVC-PR-453118.

[StephanTLavavej]

StephanTLavavej on Mar 23, 2020
I am concerned that we now have two lists of skipped tests for libcxx; this seems like it will get desynced easily. Is there some way to rely on a single list, or possibly a main list with a small secondary list of Python-runner-specific skips? Ideally, someone with a libcxx update that passes checks on GitHub should automatically pass on MSVC-internal and vice versa.

😹 😻 📆

[CaseyCarter]

Is there some way to rely on a single list, or possibly a main list with a small secondary list of Python-runner-specific skips?

I had always thought this needed to look like "teach the internal test runner to run LIT", until roughly the 10,000th time I did the "copy from expected_results.txt to skipped_tests.txt, strip std/ prefix, strip any :0 MEOW suffix, and replace / with \" dance and it occurred to me that we could simply have the internal test runner do that. It seems so obvious in hindsight.