Python code coverage for Lib/test/test_importlib/import_/test_caching.py

#	count	content
1	n/a	"""Test that sys.modules is used properly by import."""
2	n/a	from .. import util
3	n/a	import sys
4	n/a	from types import MethodType
5	n/a	import unittest
6	n/a
7	n/a
8	n/a	class UseCache:
9	n/a
10	n/a	"""When it comes to sys.modules, import prefers it over anything else.
11	n/a
12	n/a	Once a name has been resolved, sys.modules is checked to see if it contains
13	n/a	the module desired. If so, then it is returned [use cache]. If it is not
14	n/a	found, then the proper steps are taken to perform the import, but
15	n/a	sys.modules is still used to return the imported module (e.g., not what a
16	n/a	loader returns) [from cache on return]. This also applies to imports of
17	n/a	things contained within a package and thus get assigned as an attribute
18	n/a	[from cache to attribute] or pulled in thanks to a fromlist import
19	n/a	[from cache for fromlist]. But if sys.modules contains None then
20	n/a	ImportError is raised [None in cache].
21	n/a
22	n/a	"""
23	n/a
24	n/a	def test_using_cache(self):
25	n/a	# [use cache]
26	n/a	module_to_use = "some module found!"
27	n/a	with util.uncache('some_module'):
28	n/a	sys.modules['some_module'] = module_to_use
29	n/a	module = self.__import__('some_module')
30	n/a	self.assertEqual(id(module_to_use), id(module))
31	n/a
32	n/a	def test_None_in_cache(self):
33	n/a	#[None in cache]
34	n/a	name = 'using_None'
35	n/a	with util.uncache(name):
36	n/a	sys.modules[name] = None
37	n/a	with self.assertRaises(ImportError) as cm:
38	n/a	self.__import__(name)
39	n/a	self.assertEqual(cm.exception.name, name)
40	n/a
41	n/a
42	n/a	(Frozen_UseCache,
43	n/a	Source_UseCache
44	n/a	) = util.test_both(UseCache, __import__=util.__import__)
45	n/a
46	n/a
47	n/a	class ImportlibUseCache(UseCache, unittest.TestCase):
48	n/a
49	n/a	# Pertinent only to PEP 302; exec_module() doesn't return a module.
50	n/a
51	n/a	__import__ = util.__import__['Source']
52	n/a
53	n/a	def create_mock(self, *names, return_=None):
54	n/a	mock = util.mock_modules(*names)
55	n/a	original_load = mock.load_module
56	n/a	def load_module(self, fullname):
57	n/a	original_load(fullname)
58	n/a	return return_
59	n/a	mock.load_module = MethodType(load_module, mock)
60	n/a	return mock
61	n/a
62	n/a	# __import__ inconsistent between loaders and built-in import when it comes
63	n/a	# to when to use the module in sys.modules and when not to.
64	n/a	def test_using_cache_after_loader(self):
65	n/a	# [from cache on return]
66	n/a	with self.create_mock('module') as mock:
67	n/a	with util.import_state(meta_path=[mock]):
68	n/a	module = self.__import__('module')
69	n/a	self.assertEqual(id(module), id(sys.modules['module']))
70	n/a
71	n/a	# See test_using_cache_after_loader() for reasoning.
72	n/a	def test_using_cache_for_assigning_to_attribute(self):
73	n/a	# [from cache to attribute]
74	n/a	with self.create_mock('pkg.__init__', 'pkg.module') as importer:
75	n/a	with util.import_state(meta_path=[importer]):
76	n/a	module = self.__import__('pkg.module')
77	n/a	self.assertTrue(hasattr(module, 'module'))
78	n/a	self.assertEqual(id(module.module),
79	n/a	id(sys.modules['pkg.module']))
80	n/a
81	n/a	# See test_using_cache_after_loader() for reasoning.
82	n/a	def test_using_cache_for_fromlist(self):
83	n/a	# [from cache for fromlist]
84	n/a	with self.create_mock('pkg.__init__', 'pkg.module') as importer:
85	n/a	with util.import_state(meta_path=[importer]):
86	n/a	module = self.__import__('pkg', fromlist=['module'])
87	n/a	self.assertTrue(hasattr(module, 'module'))
88	n/a	self.assertEqual(id(module.module),
89	n/a	id(sys.modules['pkg.module']))
90	n/a
91	n/a
92	n/a	if __name__ == '__main__':
93	n/a	unittest.main()