[jbrown9513]

perch coverage on Python runs a pytest plugin, the mutant server, that finds the functions a mutant replaces. It asked every object in memory for __code__, and every module in sys.modules for __file__. A lazy module (one with a PEP 562 __getattr__) or a lazy proxy object imports what it stands for when asked for a name it lacks. On PrefectHQ/prefect at acc006a, in an image without Tk, that import raised ImportError: libtk8.6.so and the server stopped with exit 3.

The server now reads __code__ only from objects whose type is a function, and reads __file__ from a module's own __dict__. Neither lookup runs any code the project defines.

A new test in test/runners.test.js starts the real server on a project whose conftest.py puts a lazy module in sys.modules and a lazy object in memory, both raising ImportError. Before the first change the server stopped; with only the first change every mutant came back invalid. With both, the mutant runs and its test fails.

npm run check passes, with pytest installed. perch scan --since origin/main reports nothing.

[perchcode-bot]

Perch Scan: no issues in 1 method at ea60f82.

See the scan