Supress pytest rewrite warnings for plugins

[chmp]

When running ipytest multiple times, the rewrite warnings for plugins in pytest are triggered.

I raised the issue upstream: pytest-dev/pytest#5432

Depending on the repsonse, try to work around locally. My current ideas:

1. Can't filter rewrite warnings pytest-dev/pytest#4439
2. try restoring self._rewritten_names before each run

[chmp]

Re Option 2, this would work:

import sys
from _pytest import assertion
from _pytest.assertion import rewrite, AssertionState


def custom_install_importhook(config):
    """Try to install the rewrite hook, raise SystemError if it fails."""
    config._assertstate = AssertionState(config, "rewrite")
    
    installed = any(
        isinstance(hook, rewrite.AssertionRewritingHook) for hook in sys.meta_path
    )
    
    if not installed:
        config._assertstate.hook = hook = rewrite.AssertionRewritingHook(config)
        sys.meta_path.insert(0, hook)
        config._assertstate.trace("installed rewrite import hook")
    
    else:
        hook, = [hook for hook in sys.meta_path if isinstance(hook, rewrite.AssertionRewritingHook)]
    
    config._assertstate.hook = hook
    
    return hook

assertion.install_importhook = custom_install_importhook

[chmp]

Fixed up stream with the new pytest release.