Adam Johnson

This needs some research into which function inside numpy reads the clock. If it’s something completely custom, it may be unfeasible to patch it.

I didn’t add a changelog note yet because that would conflict with #384.

Tests are passing but codecov is failing, as noted on #384.

Rebased. > @adamchainz - can you add unit tests to achieve required code coverage? Done. The flagged code paths weren't actually tested before, either 😅 .

Sure, we could add mocking for `perf_counter` and `perf_counter_ns`. They fit in the same family as `time.monotonic`. The `time.monotonic` patch seems to have broken asyncio tests: #387. I’m thinking of...

Given the problems reported with monotonic mocking in #387, I’m considering rolling it back. I definitely don’t feel confident expanding to `perf_counter` now, since it may break more stuff, and...