Problem

In the Scaling Up Testing Using Build Matrices step of episode 2.3, the CI is set to install dependencies from requirements.txt, where dependencies are frozen earlier. The tests are then run on a matrix of Python versions that includes 3.10.

One of the dependencies is contourpy, which dropped support for Python 3.10 as of version 1.3.3.

-> If requirements.txt was frozen using a Python >= 3.11, this results in the dependency installation step failing for Python 3.10, as no valid release is available on PyPI.

Example

Solutions

Assuming we want this initial matrix run to completely succeed, the quick fix would be to update the Python versions in the CI matrix to avoid Python 3.10.