Test Reordering: Run previously failing tests first (#101123)
Makes the CI prioritize running any test files that had a failing test in a previous iteration of the given PR.
A follow up to https://github.com/pytorch/pytorch/pull/100522 which makes the `.pytest_cache` available to use here
A concrete example:
1. Person A pushes a new commit and creates a PR.
2. 2 hours later, test_im_now_broken.py fails
3. Person A attempts to fix the test, but the test is actually still broken
4. The CI, seeing that test_im_now_broken.py had failed on a previous run, will now prioritize running that test first. Instead of waiting another 2 hours to get a signal, Person A only needs to wait ~15 minutes (which is how long it takes for tests to start running)
# Testing
I modified a file to make the tests invoking it fail and triggered CI twice with this failure.
First run: https://github.com/pytorch/pytorch/actions/runs/4963943209/jobs/8883800811
Test step took 1h 9m to run
Second run: https://github.com/pytorch/pytorch/actions/runs/4965016776/jobs/8885657992
Test step failed within 2m 27s
Pull Request resolved: https://github.com/pytorch/pytorch/pull/101123
Approved by: https://github.com/malfet, https://github.com/huydhn
