[torchlib] pytest-subtest does not (seem to) support subtest filtering

[BowenBao]

Not sure how to selectively run a single subtest. It would be very helpful in cases like debugging a test failure that contains like 20+ subtest failures. Since otherwise the logs are cluttered.

Maybe it's me not knowing the proper command... Related issue at pytest-dev/pytest-subtests#100

[justinchuby]

I am not aware of this either

[BowenBao]

Probably nothing like -k that we can use, the subtests are not structurally named. Perhaps we can achieve something similar with fixtures.