| 1 | n/a | """Test that sys.modules is used properly by import.""" |
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| 2 | n/a | from .. import util |
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| 3 | n/a | from . import util as import_util |
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| 4 | n/a | import sys |
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| 5 | n/a | from types import MethodType |
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| 6 | n/a | import unittest |
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| 7 | n/a | |
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| 8 | n/a | |
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| 9 | n/a | class UseCache(unittest.TestCase): |
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| 10 | n/a | |
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| 11 | n/a | """When it comes to sys.modules, import prefers it over anything else. |
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| 12 | n/a | |
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| 13 | n/a | Once a name has been resolved, sys.modules is checked to see if it contains |
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| 14 | n/a | the module desired. If so, then it is returned [use cache]. If it is not |
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| 15 | n/a | found, then the proper steps are taken to perform the import, but |
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| 16 | n/a | sys.modules is still used to return the imported module (e.g., not what a |
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| 17 | n/a | loader returns) [from cache on return]. This also applies to imports of |
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| 18 | n/a | things contained within a package and thus get assigned as an attribute |
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| 19 | n/a | [from cache to attribute] or pulled in thanks to a fromlist import |
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| 20 | n/a | [from cache for fromlist]. But if sys.modules contains None then |
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| 21 | n/a | ImportError is raised [None in cache]. |
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| 22 | n/a | |
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| 23 | n/a | """ |
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| 24 | n/a | def test_using_cache(self): |
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| 25 | n/a | # [use cache] |
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| 26 | n/a | module_to_use = "some module found!" |
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| 27 | n/a | with util.uncache(module_to_use): |
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| 28 | n/a | sys.modules['some_module'] = module_to_use |
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| 29 | n/a | module = import_util.import_('some_module') |
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| 30 | n/a | self.assertEqual(id(module_to_use), id(module)) |
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| 31 | n/a | |
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| 32 | n/a | def test_None_in_cache(self): |
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| 33 | n/a | #[None in cache] |
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| 34 | n/a | name = 'using_None' |
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| 35 | n/a | with util.uncache(name): |
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| 36 | n/a | sys.modules[name] = None |
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| 37 | n/a | with self.assertRaises(ImportError) as cm: |
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| 38 | n/a | import_util.import_(name) |
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| 39 | n/a | self.assertEqual(cm.exception.name, name) |
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| 40 | n/a | |
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| 41 | n/a | def create_mock(self, *names, return_=None): |
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| 42 | n/a | mock = util.mock_modules(*names) |
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| 43 | n/a | original_load = mock.load_module |
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| 44 | n/a | def load_module(self, fullname): |
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| 45 | n/a | original_load(fullname) |
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| 46 | n/a | return return_ |
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| 47 | n/a | mock.load_module = MethodType(load_module, mock) |
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| 48 | n/a | return mock |
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| 49 | n/a | |
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| 50 | n/a | # __import__ inconsistent between loaders and built-in import when it comes |
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| 51 | n/a | # to when to use the module in sys.modules and when not to. |
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| 52 | n/a | @import_util.importlib_only |
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| 53 | n/a | def test_using_cache_after_loader(self): |
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| 54 | n/a | # [from cache on return] |
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| 55 | n/a | with self.create_mock('module') as mock: |
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| 56 | n/a | with util.import_state(meta_path=[mock]): |
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| 57 | n/a | module = import_util.import_('module') |
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| 58 | n/a | self.assertEqual(id(module), id(sys.modules['module'])) |
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| 59 | n/a | |
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| 60 | n/a | # See test_using_cache_after_loader() for reasoning. |
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| 61 | n/a | @import_util.importlib_only |
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| 62 | n/a | def test_using_cache_for_assigning_to_attribute(self): |
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| 63 | n/a | # [from cache to attribute] |
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| 64 | n/a | with self.create_mock('pkg.__init__', 'pkg.module') as importer: |
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| 65 | n/a | with util.import_state(meta_path=[importer]): |
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| 66 | n/a | module = import_util.import_('pkg.module') |
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| 67 | n/a | self.assertTrue(hasattr(module, 'module')) |
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| 68 | n/a | self.assertEqual(id(module.module), |
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| 69 | n/a | id(sys.modules['pkg.module'])) |
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| 70 | n/a | |
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| 71 | n/a | # See test_using_cache_after_loader() for reasoning. |
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| 72 | n/a | @import_util.importlib_only |
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| 73 | n/a | def test_using_cache_for_fromlist(self): |
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| 74 | n/a | # [from cache for fromlist] |
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| 75 | n/a | with self.create_mock('pkg.__init__', 'pkg.module') as importer: |
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| 76 | n/a | with util.import_state(meta_path=[importer]): |
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| 77 | n/a | module = import_util.import_('pkg', fromlist=['module']) |
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| 78 | n/a | self.assertTrue(hasattr(module, 'module')) |
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| 79 | n/a | self.assertEqual(id(module.module), |
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| 80 | n/a | id(sys.modules['pkg.module'])) |
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| 81 | n/a | |
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| 82 | n/a | |
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| 83 | n/a | def test_main(): |
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| 84 | n/a | from test.support import run_unittest |
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| 85 | n/a | run_unittest(UseCache) |
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| 86 | n/a | |
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| 87 | n/a | if __name__ == '__main__': |
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| 88 | n/a | test_main() |
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