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import sys
from importlib.metadata import DistributionFinder, PathDistribution
from os import path
from pathlib import Path
class DummyDistributionFinder(DistributionFinder):
"""
Injects a dummy distribution into the meta path finder, so that we can
pretend like it's been pip installed during unit tests (i.e., so that we
can test ``EntryPointsClassRegistry``), without polluting the persistent
virtualenv.
"""
DUMMY_PACKAGE_DIR = 'dummy_package.egg-info'
@classmethod
def install(cls):
for finder in sys.meta_path:
if isinstance(finder, cls):
# If we've already installed an instance of the class, then
# something is probably wrong with our tests.
raise ValueError(f'{cls.__name__} is already installed')
sys.meta_path.append(cls())
@classmethod
def uninstall(cls):
for i, finder in enumerate(sys.meta_path):
if isinstance(finder, cls):
sys.meta_path.pop(i)
return
else:
# If we didn't find an installed instance of the class, then
# something is probably wrong with our tests.
raise ValueError(f'{cls.__name__} was not installed')
def find_distributions(self, context=...) -> list[PathDistribution]:
return [PathDistribution(
Path(path.join(path.dirname(__file__), self.DUMMY_PACKAGE_DIR))
)]
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