testing: not clear whether parallel tests can run in parallel with themselves #18914
Description
https://golang.org/pkg/testing/#T.Parallel says:
Parallel signals that this test is to be run in parallel with (and only with) other parallel tests.
Is the test itself included in other parallel tests? You could understand that other means it's not included, but the wording isn't clear to me or a couple of people I've asked.
This is important because people (including myself) often write parallel tests in a way that they don't break other parallel tests, but not themselves. For example, it might use t.Name() as a unique identifier/key in a database.
I ran some quick tests and it does seem like a parallel test never runs in parallel with itself. Will post a doc CL soon.