testing: be more specific in Parallel error

[rsc]

panic: testing: test using t.Setenv, t.Chdir, or cryptotest.SetGlobalRandom can not use t.Parallel [recovered, repanicked]

This error should say which one is being called at that moment.
And if t.Parallel is what is being called, the error should say which one was called.

(It's confusing to see an error about cryptotest.SetGlobalRandom in one of my tests that has nothing to do with crypto at all!)

[gabyhelp]

Related Issues

• proposal: testing: expose denyParallel #78614
• proposal: testing: ability to tell if test is running in parallel #70017
• testing: stack unavailable when a parallel test times out #18042 (closed)

Related Code Changes

• testing: fail if T.Setenv is called via T.Run in a parallel test

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[gopherbot]

Change https://go.dev/cl/798641 mentions this issue: testing: name the conflicting operation in t.Parallel panics

[gopherbot]

Change https://go.dev/cl/799860 mentions this issue: testing: be more specific in Parallel error

[prattmic]

cc @adonovan @neild