replace timer test with a mocked variant (#45173)
Summary:
I noticed that the recently introduced adaptive_autorange tests occasionally timeout CI, and I've been meaning to improve the Timer tests for a while. This PR allows unit tests to swap the measurement portion of `Timer` with a deterministic mock so we can thoroughly test behavior without having to worry about flaky CI measurements. It also means that the tests can be much more detailed and still finish very quickly.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/45173
Test Plan: You're lookin' at it.
Reviewed By: ezyang
Differential Revision: D23873548
Pulled By: robieta
fbshipit-source-id: 26113e5cea0cbf46909b9bf5e90c878c29e87e88
