The pytest-xdist plugin extends pytest with some unique test execution modes:

- test run parallelization: if you have multiple CPUs or hosts you can use
those for a combined test run. This allows to speed up development or to use
special resources of remote machines.
- --looponfail: run your tests repeatedly in a subprocess. After each run
pytest waits until a file in your project changes and then re-runs the
previously failing tests. This is repeated until all tests pass after which
again a full run is performed.
- Multi-Platform coverage: you can specify different Python interpreters or
different platforms and run tests in parallel on all of them.