There are some tests for the cases generator in Tools/cases_generator/test_generator.py, but several things are wrong with these:

• They are currently broken
• They depend on pytest
• They aren't run in CI
• They are incomplete

Let's fix that (in that order).

Linked PRs

• gh-105540: Fix code generator tests #105707
• gh-105540: Convertpytest tests ofcases_generator to regular tests #106713
• gh-105540: Show source files relative to root #106927
• gh-105540: Improve relative paths ingenerate_cases.py #106942