add tests for torch.testing (#54784)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/54784
* #54769 make torch.testing asserts importable
Test Plan: Imported from OSS
Reviewed By: jbschlosser
Differential Revision: D27717422
Pulled By: mruberry
fbshipit-source-id: 7526af4f17d8ffcc4ea5e5a5d98f07ceac89df40
