133 lines
4.2 KiB
Python
133 lines
4.2 KiB
Python
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import importlib
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from importlib import abc
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from importlib import util
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import unittest
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from . import util as test_util
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class CollectInit:
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def __init__(self, *args, **kwargs):
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self.args = args
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self.kwargs = kwargs
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def exec_module(self, module):
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return self
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class LazyLoaderFactoryTests(unittest.TestCase):
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def test_init(self):
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factory = util.LazyLoader.factory(CollectInit)
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# E.g. what importlib.machinery.FileFinder instantiates loaders with
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# plus keyword arguments.
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lazy_loader = factory('module name', 'module path', kw='kw')
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loader = lazy_loader.loader
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self.assertEqual(('module name', 'module path'), loader.args)
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self.assertEqual({'kw': 'kw'}, loader.kwargs)
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def test_validation(self):
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# No exec_module(), no lazy loading.
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with self.assertRaises(TypeError):
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util.LazyLoader.factory(object)
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class TestingImporter(abc.MetaPathFinder, abc.Loader):
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module_name = 'lazy_loader_test'
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mutated_name = 'changed'
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loaded = None
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source_code = 'attr = 42; __name__ = {!r}'.format(mutated_name)
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def find_spec(self, name, path, target=None):
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if name != self.module_name:
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return None
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return util.spec_from_loader(name, util.LazyLoader(self))
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def exec_module(self, module):
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exec(self.source_code, module.__dict__)
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self.loaded = module
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class LazyLoaderTests(unittest.TestCase):
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def test_init(self):
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with self.assertRaises(TypeError):
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util.LazyLoader(object)
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def new_module(self, source_code=None):
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loader = TestingImporter()
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if source_code is not None:
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loader.source_code = source_code
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spec = util.spec_from_loader(TestingImporter.module_name,
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util.LazyLoader(loader))
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module = spec.loader.create_module(spec)
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module.__spec__ = spec
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module.__loader__ = spec.loader
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spec.loader.exec_module(module)
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# Module is now lazy.
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self.assertIsNone(loader.loaded)
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return module
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def test_e2e(self):
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# End-to-end test to verify the load is in fact lazy.
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importer = TestingImporter()
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assert importer.loaded is None
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with test_util.uncache(importer.module_name):
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with test_util.import_state(meta_path=[importer]):
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module = importlib.import_module(importer.module_name)
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self.assertIsNone(importer.loaded)
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# Trigger load.
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self.assertEqual(module.__loader__, importer)
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self.assertIsNotNone(importer.loaded)
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self.assertEqual(module, importer.loaded)
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def test_attr_unchanged(self):
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# An attribute only mutated as a side-effect of import should not be
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# changed needlessly.
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module = self.new_module()
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self.assertEqual(TestingImporter.mutated_name, module.__name__)
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def test_new_attr(self):
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# A new attribute should persist.
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module = self.new_module()
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module.new_attr = 42
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self.assertEqual(42, module.new_attr)
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def test_mutated_preexisting_attr(self):
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# Changing an attribute that already existed on the module --
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# e.g. __name__ -- should persist.
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module = self.new_module()
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module.__name__ = 'bogus'
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self.assertEqual('bogus', module.__name__)
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def test_mutated_attr(self):
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# Changing an attribute that comes into existence after an import
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# should persist.
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module = self.new_module()
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module.attr = 6
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self.assertEqual(6, module.attr)
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def test_delete_eventual_attr(self):
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# Deleting an attribute should stay deleted.
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module = self.new_module()
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del module.attr
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self.assertFalse(hasattr(module, 'attr'))
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def test_delete_preexisting_attr(self):
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module = self.new_module()
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del module.__name__
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self.assertFalse(hasattr(module, '__name__'))
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def test_module_substitution_error(self):
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source_code = 'import sys; sys.modules[__name__] = 42'
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module = self.new_module(source_code)
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with test_util.uncache(TestingImporter.module_name):
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with self.assertRaises(ValueError):
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module.__name__
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if __name__ == '__main__':
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unittest.main()
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