Django Test Parallelization

Parallel test execution is a multiplier after a suite is isolated. Treat failures under parallel execution as evidence of hidden shared state until proven otherwise.

Readiness Workflow

1. Measure serial runtime first.

   • If the suite is already dominated by startup or database creation, parallelism may not help enough on its own.

2. Check isolation before enabling parallelism as the default.

   • Run in reverse order.
   • Run with randomized order when reverse order is not enough.
   • Preserve random seeds so failures can be reproduced.

3. Enable the runner deliberately.

   • Django runner: install tblib, then run python manage.py test --parallel.
   • pytest-django: install pytest-xdist, then run pytest -n auto.