Python code coverage for Lib/test/test_isinstance.py

#	count	content
1	n/a	# Tests some corner cases with isinstance() and issubclass(). While these
2	n/a	# tests use new style classes and properties, they actually do whitebox
3	n/a	# testing of error conditions uncovered when using extension types.
4	n/a
5	n/a	import unittest
6	n/a	import sys
7	n/a
8	n/a
9	n/a
10	n/a	class TestIsInstanceExceptions(unittest.TestCase):
11	n/a	# Test to make sure that an AttributeError when accessing the instance's
12	n/a	# class's bases is masked. This was actually a bug in Python 2.2 and
13	n/a	# 2.2.1 where the exception wasn't caught but it also wasn't being cleared
14	n/a	# (leading to an "undetected error" in the debug build). Set up is,
15	n/a	# isinstance(inst, cls) where:
16	n/a	#
17	n/a	# - cls isn't a type, or a tuple
18	n/a	# - cls has a __bases__ attribute
19	n/a	# - inst has a __class__ attribute
20	n/a	# - inst.__class__ as no __bases__ attribute
21	n/a	#
22	n/a	# Sounds complicated, I know, but this mimics a situation where an
23	n/a	# extension type raises an AttributeError when its __bases__ attribute is
24	n/a	# gotten. In that case, isinstance() should return False.
25	n/a	def test_class_has_no_bases(self):
26	n/a	class I(object):
27	n/a	def getclass(self):
28	n/a	# This must return an object that has no __bases__ attribute
29	n/a	return None
30	n/a	__class__ = property(getclass)
31	n/a
32	n/a	class C(object):
33	n/a	def getbases(self):
34	n/a	return ()
35	n/a	__bases__ = property(getbases)
36	n/a
37	n/a	self.assertEqual(False, isinstance(I(), C()))
38	n/a
39	n/a	# Like above except that inst.__class__.__bases__ raises an exception
40	n/a	# other than AttributeError
41	n/a	def test_bases_raises_other_than_attribute_error(self):
42	n/a	class E(object):
43	n/a	def getbases(self):
44	n/a	raise RuntimeError
45	n/a	__bases__ = property(getbases)
46	n/a
47	n/a	class I(object):
48	n/a	def getclass(self):
49	n/a	return E()
50	n/a	__class__ = property(getclass)
51	n/a
52	n/a	class C(object):
53	n/a	def getbases(self):
54	n/a	return ()
55	n/a	__bases__ = property(getbases)
56	n/a
57	n/a	self.assertRaises(RuntimeError, isinstance, I(), C())
58	n/a
59	n/a	# Here's a situation where getattr(cls, '__bases__') raises an exception.
60	n/a	# If that exception is not AttributeError, it should not get masked
61	n/a	def test_dont_mask_non_attribute_error(self):
62	n/a	class I: pass
63	n/a
64	n/a	class C(object):
65	n/a	def getbases(self):
66	n/a	raise RuntimeError
67	n/a	__bases__ = property(getbases)
68	n/a
69	n/a	self.assertRaises(RuntimeError, isinstance, I(), C())
70	n/a
71	n/a	# Like above, except that getattr(cls, '__bases__') raises an
72	n/a	# AttributeError, which /should/ get masked as a TypeError
73	n/a	def test_mask_attribute_error(self):
74	n/a	class I: pass
75	n/a
76	n/a	class C(object):
77	n/a	def getbases(self):
78	n/a	raise AttributeError
79	n/a	__bases__ = property(getbases)
80	n/a
81	n/a	self.assertRaises(TypeError, isinstance, I(), C())
82	n/a
83	n/a	# check that we don't mask non AttributeErrors
84	n/a	# see: http://bugs.python.org/issue1574217
85	n/a	def test_isinstance_dont_mask_non_attribute_error(self):
86	n/a	class C(object):
87	n/a	def getclass(self):
88	n/a	raise RuntimeError
89	n/a	__class__ = property(getclass)
90	n/a
91	n/a	c = C()
92	n/a	self.assertRaises(RuntimeError, isinstance, c, bool)
93	n/a
94	n/a	# test another code path
95	n/a	class D: pass
96	n/a	self.assertRaises(RuntimeError, isinstance, c, D)
97	n/a
98	n/a
99	n/a	# These tests are similar to above, but tickle certain code paths in
100	n/a	# issubclass() instead of isinstance() -- really PyObject_IsSubclass()
101	n/a	# vs. PyObject_IsInstance().
102	n/a	class TestIsSubclassExceptions(unittest.TestCase):
103	n/a	def test_dont_mask_non_attribute_error(self):
104	n/a	class C(object):
105	n/a	def getbases(self):
106	n/a	raise RuntimeError
107	n/a	__bases__ = property(getbases)
108	n/a
109	n/a	class S(C): pass
110	n/a
111	n/a	self.assertRaises(RuntimeError, issubclass, C(), S())
112	n/a
113	n/a	def test_mask_attribute_error(self):
114	n/a	class C(object):
115	n/a	def getbases(self):
116	n/a	raise AttributeError
117	n/a	__bases__ = property(getbases)
118	n/a
119	n/a	class S(C): pass
120	n/a
121	n/a	self.assertRaises(TypeError, issubclass, C(), S())
122	n/a
123	n/a	# Like above, but test the second branch, where the __bases__ of the
124	n/a	# second arg (the cls arg) is tested. This means the first arg must
125	n/a	# return a valid __bases__, and it's okay for it to be a normal --
126	n/a	# unrelated by inheritance -- class.
127	n/a	def test_dont_mask_non_attribute_error_in_cls_arg(self):
128	n/a	class B: pass
129	n/a
130	n/a	class C(object):
131	n/a	def getbases(self):
132	n/a	raise RuntimeError
133	n/a	__bases__ = property(getbases)
134	n/a
135	n/a	self.assertRaises(RuntimeError, issubclass, B, C())
136	n/a
137	n/a	def test_mask_attribute_error_in_cls_arg(self):
138	n/a	class B: pass
139	n/a
140	n/a	class C(object):
141	n/a	def getbases(self):
142	n/a	raise AttributeError
143	n/a	__bases__ = property(getbases)
144	n/a
145	n/a	self.assertRaises(TypeError, issubclass, B, C())
146	n/a
147	n/a
148	n/a
149	n/a	# meta classes for creating abstract classes and instances
150	n/a	class AbstractClass(object):
151	n/a	def __init__(self, bases):
152	n/a	self.bases = bases
153	n/a
154	n/a	def getbases(self):
155	n/a	return self.bases
156	n/a	__bases__ = property(getbases)
157	n/a
158	n/a	def __call__(self):
159	n/a	return AbstractInstance(self)
160	n/a
161	n/a	class AbstractInstance(object):
162	n/a	def __init__(self, klass):
163	n/a	self.klass = klass
164	n/a
165	n/a	def getclass(self):
166	n/a	return self.klass
167	n/a	__class__ = property(getclass)
168	n/a
169	n/a	# abstract classes
170	n/a	AbstractSuper = AbstractClass(bases=())
171	n/a
172	n/a	AbstractChild = AbstractClass(bases=(AbstractSuper,))
173	n/a
174	n/a	# normal classes
175	n/a	class Super:
176	n/a	pass
177	n/a
178	n/a	class Child(Super):
179	n/a	pass
180	n/a
181	n/a	# new-style classes
182	n/a	class NewSuper(object):
183	n/a	pass
184	n/a
185	n/a	class NewChild(NewSuper):
186	n/a	pass
187	n/a
188	n/a
189	n/a
190	n/a	class TestIsInstanceIsSubclass(unittest.TestCase):
191	n/a	# Tests to ensure that isinstance and issubclass work on abstract
192	n/a	# classes and instances. Before the 2.2 release, TypeErrors were
193	n/a	# raised when boolean values should have been returned. The bug was
194	n/a	# triggered by mixing 'normal' classes and instances were with
195	n/a	# 'abstract' classes and instances. This case tries to test all
196	n/a	# combinations.
197	n/a
198	n/a	def test_isinstance_normal(self):
199	n/a	# normal instances
200	n/a	self.assertEqual(True, isinstance(Super(), Super))
201	n/a	self.assertEqual(False, isinstance(Super(), Child))
202	n/a	self.assertEqual(False, isinstance(Super(), AbstractSuper))
203	n/a	self.assertEqual(False, isinstance(Super(), AbstractChild))
204	n/a
205	n/a	self.assertEqual(True, isinstance(Child(), Super))
206	n/a	self.assertEqual(False, isinstance(Child(), AbstractSuper))
207	n/a
208	n/a	def test_isinstance_abstract(self):
209	n/a	# abstract instances
210	n/a	self.assertEqual(True, isinstance(AbstractSuper(), AbstractSuper))
211	n/a	self.assertEqual(False, isinstance(AbstractSuper(), AbstractChild))
212	n/a	self.assertEqual(False, isinstance(AbstractSuper(), Super))
213	n/a	self.assertEqual(False, isinstance(AbstractSuper(), Child))
214	n/a
215	n/a	self.assertEqual(True, isinstance(AbstractChild(), AbstractChild))
216	n/a	self.assertEqual(True, isinstance(AbstractChild(), AbstractSuper))
217	n/a	self.assertEqual(False, isinstance(AbstractChild(), Super))
218	n/a	self.assertEqual(False, isinstance(AbstractChild(), Child))
219	n/a
220	n/a	def test_subclass_normal(self):
221	n/a	# normal classes
222	n/a	self.assertEqual(True, issubclass(Super, Super))
223	n/a	self.assertEqual(False, issubclass(Super, AbstractSuper))
224	n/a	self.assertEqual(False, issubclass(Super, Child))
225	n/a
226	n/a	self.assertEqual(True, issubclass(Child, Child))
227	n/a	self.assertEqual(True, issubclass(Child, Super))
228	n/a	self.assertEqual(False, issubclass(Child, AbstractSuper))
229	n/a
230	n/a	def test_subclass_abstract(self):
231	n/a	# abstract classes
232	n/a	self.assertEqual(True, issubclass(AbstractSuper, AbstractSuper))
233	n/a	self.assertEqual(False, issubclass(AbstractSuper, AbstractChild))
234	n/a	self.assertEqual(False, issubclass(AbstractSuper, Child))
235	n/a
236	n/a	self.assertEqual(True, issubclass(AbstractChild, AbstractChild))
237	n/a	self.assertEqual(True, issubclass(AbstractChild, AbstractSuper))
238	n/a	self.assertEqual(False, issubclass(AbstractChild, Super))
239	n/a	self.assertEqual(False, issubclass(AbstractChild, Child))
240	n/a
241	n/a	def test_subclass_tuple(self):
242	n/a	# test with a tuple as the second argument classes
243	n/a	self.assertEqual(True, issubclass(Child, (Child,)))
244	n/a	self.assertEqual(True, issubclass(Child, (Super,)))
245	n/a	self.assertEqual(False, issubclass(Super, (Child,)))
246	n/a	self.assertEqual(True, issubclass(Super, (Child, Super)))
247	n/a	self.assertEqual(False, issubclass(Child, ()))
248	n/a	self.assertEqual(True, issubclass(Super, (Child, (Super,))))
249	n/a
250	n/a	self.assertEqual(True, issubclass(NewChild, (NewChild,)))
251	n/a	self.assertEqual(True, issubclass(NewChild, (NewSuper,)))
252	n/a	self.assertEqual(False, issubclass(NewSuper, (NewChild,)))
253	n/a	self.assertEqual(True, issubclass(NewSuper, (NewChild, NewSuper)))
254	n/a	self.assertEqual(False, issubclass(NewChild, ()))
255	n/a	self.assertEqual(True, issubclass(NewSuper, (NewChild, (NewSuper,))))
256	n/a
257	n/a	self.assertEqual(True, issubclass(int, (int, (float, int))))
258	n/a	self.assertEqual(True, issubclass(str, (str, (Child, NewChild, str))))
259	n/a
260	n/a	def test_subclass_recursion_limit(self):
261	n/a	# make sure that issubclass raises RecursionError before the C stack is
262	n/a	# blown
263	n/a	self.assertRaises(RecursionError, blowstack, issubclass, str, str)
264	n/a
265	n/a	def test_isinstance_recursion_limit(self):
266	n/a	# make sure that issubclass raises RecursionError before the C stack is
267	n/a	# blown
268	n/a	self.assertRaises(RecursionError, blowstack, isinstance, '', str)
269	n/a
270	n/a	def blowstack(fxn, arg, compare_to):
271	n/a	# Make sure that calling isinstance with a deeply nested tuple for its
272	n/a	# argument will raise RecursionError eventually.
273	n/a	tuple_arg = (compare_to,)
274	n/a	for cnt in range(sys.getrecursionlimit()+5):
275	n/a	tuple_arg = (tuple_arg,)
276	n/a	fxn(arg, tuple_arg)
277	n/a
278	n/a
279	n/a	if __name__ == '__main__':
280	n/a	unittest.main()