Fail tests which leak hass instances

[emontnemery]

Proposed change

Fail tests which leak many hass instances

Not at all ready for merge, the PR is opened to gain some understanding about how common the issue is

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[home-assistant]

Hey there @home-assistant/matter, mind taking a look at this pull request as it has been labeled with an integration (matter) you are listed as a code owner for? Thanks!

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[bdraco]

If you are looking for more lrus, profiler.lru_stats action might be useful.

[emontnemery]

Some of the leakage is caused by python/cpython#133543, worked around by removing some cached_property in the tests.

[codecov]

❌ We are unable to process any of the uploaded JUnit XML files. Please ensure your files are in the right format.

[emontnemery]

A lot of memory is leaked (or technically, kept until the test session is finished) because tests are parametrized with mutable objects which end up directly or indirectly referencing hass.

The most common cases are:

• Tests parametrized with Exception instances, which will have a traceback attached to them when raised in the test
• Tests parametrized with pytest.raises instances, which will have a traceback attached to them when used in the test
• Tests paramatrized with Mock instances, which will keep references to hass either directly or via the call history

Parametrizing like this is suggested in the pytest documentation, and I've opened an issue on pytest to get some input on if we should expect pytest to handle this case better or if we should change our tests: pytest-dev/pytest#13410