Problems faced when downstream testing Python packages

Downstream testing, performed by software redistributors like Linux distributions, serves a different purpose than upstream testing. While upstream testing ensures the current code works in reference environments, downstream testing verifies that a specific package version functions properly in the intended environment. However, downstream testers often encounter issues with test suites that assume a disposable environment, require outdated package versions, have incompatibilities caused by additional packages, rely on internet resources, demand containers for testing, include fragile tests with timeouts, impose unconditional test dependencies, or conduct package quality checks that may not be critical for downstream purposes.