Python code coverage for Lib/test/test_slice.py

#	count	content
1	n/a	# tests for slice objects; in particular the indices method.
2	n/a
3	n/a	import itertools
4	n/a	import operator
5	n/a	import sys
6	n/a	import unittest
7	n/a	import weakref
8	n/a
9	n/a	from pickle import loads, dumps
10	n/a	from test import support
11	n/a
12	n/a
13	n/a	def evaluate_slice_index(arg):
14	n/a	"""
15	n/a	Helper function to convert a slice argument to an integer, and raise
16	n/a	TypeError with a suitable message on failure.
17	n/a
18	n/a	"""
19	n/a	if hasattr(arg, '__index__'):
20	n/a	return operator.index(arg)
21	n/a	else:
22	n/a	raise TypeError(
23	n/a	"slice indices must be integers or "
24	n/a	"None or have an __index__ method")
25	n/a
26	n/a	def slice_indices(slice, length):
27	n/a	"""
28	n/a	Reference implementation for the slice.indices method.
29	n/a
30	n/a	"""
31	n/a	# Compute step and length as integers.
32	n/a	length = operator.index(length)
33	n/a	step = 1 if slice.step is None else evaluate_slice_index(slice.step)
34	n/a
35	n/a	# Raise ValueError for negative length or zero step.
36	n/a	if length < 0:
37	n/a	raise ValueError("length should not be negative")
38	n/a	if step == 0:
39	n/a	raise ValueError("slice step cannot be zero")
40	n/a
41	n/a	# Find lower and upper bounds for start and stop.
42	n/a	lower = -1 if step < 0 else 0
43	n/a	upper = length - 1 if step < 0 else length
44	n/a
45	n/a	# Compute start.
46	n/a	if slice.start is None:
47	n/a	start = upper if step < 0 else lower
48	n/a	else:
49	n/a	start = evaluate_slice_index(slice.start)
50	n/a	start = max(start + length, lower) if start < 0 else min(start, upper)
51	n/a
52	n/a	# Compute stop.
53	n/a	if slice.stop is None:
54	n/a	stop = lower if step < 0 else upper
55	n/a	else:
56	n/a	stop = evaluate_slice_index(slice.stop)
57	n/a	stop = max(stop + length, lower) if stop < 0 else min(stop, upper)
58	n/a
59	n/a	return start, stop, step
60	n/a
61	n/a
62	n/a	# Class providing an __index__ method. Used for testing slice.indices.
63	n/a
64	n/a	class MyIndexable(object):
65	n/a	def __init__(self, value):
66	n/a	self.value = value
67	n/a
68	n/a	def __index__(self):
69	n/a	return self.value
70	n/a
71	n/a
72	n/a	class SliceTest(unittest.TestCase):
73	n/a
74	n/a	def test_constructor(self):
75	n/a	self.assertRaises(TypeError, slice)
76	n/a	self.assertRaises(TypeError, slice, 1, 2, 3, 4)
77	n/a
78	n/a	def test_repr(self):
79	n/a	self.assertEqual(repr(slice(1, 2, 3)), "slice(1, 2, 3)")
80	n/a
81	n/a	def test_hash(self):
82	n/a	# Verify clearing of SF bug #800796
83	n/a	self.assertRaises(TypeError, hash, slice(5))
84	n/a	with self.assertRaises(TypeError):
85	n/a	slice(5).__hash__()
86	n/a
87	n/a	def test_cmp(self):
88	n/a	s1 = slice(1, 2, 3)
89	n/a	s2 = slice(1, 2, 3)
90	n/a	s3 = slice(1, 2, 4)
91	n/a	self.assertEqual(s1, s2)
92	n/a	self.assertNotEqual(s1, s3)
93	n/a	self.assertNotEqual(s1, None)
94	n/a	self.assertNotEqual(s1, (1, 2, 3))
95	n/a	self.assertNotEqual(s1, "")
96	n/a
97	n/a	class Exc(Exception):
98	n/a	pass
99	n/a
100	n/a	class BadCmp(object):
101	n/a	def __eq__(self, other):
102	n/a	raise Exc
103	n/a
104	n/a	s1 = slice(BadCmp())
105	n/a	s2 = slice(BadCmp())
106	n/a	self.assertEqual(s1, s1)
107	n/a	self.assertRaises(Exc, lambda: s1 == s2)
108	n/a
109	n/a	s1 = slice(1, BadCmp())
110	n/a	s2 = slice(1, BadCmp())
111	n/a	self.assertEqual(s1, s1)
112	n/a	self.assertRaises(Exc, lambda: s1 == s2)
113	n/a
114	n/a	s1 = slice(1, 2, BadCmp())
115	n/a	s2 = slice(1, 2, BadCmp())
116	n/a	self.assertEqual(s1, s1)
117	n/a	self.assertRaises(Exc, lambda: s1 == s2)
118	n/a
119	n/a	def test_members(self):
120	n/a	s = slice(1)
121	n/a	self.assertEqual(s.start, None)
122	n/a	self.assertEqual(s.stop, 1)
123	n/a	self.assertEqual(s.step, None)
124	n/a
125	n/a	s = slice(1, 2)
126	n/a	self.assertEqual(s.start, 1)
127	n/a	self.assertEqual(s.stop, 2)
128	n/a	self.assertEqual(s.step, None)
129	n/a
130	n/a	s = slice(1, 2, 3)
131	n/a	self.assertEqual(s.start, 1)
132	n/a	self.assertEqual(s.stop, 2)
133	n/a	self.assertEqual(s.step, 3)
134	n/a
135	n/a	class AnyClass:
136	n/a	pass
137	n/a
138	n/a	obj = AnyClass()
139	n/a	s = slice(obj)
140	n/a	self.assertTrue(s.stop is obj)
141	n/a
142	n/a	def check_indices(self, slice, length):
143	n/a	try:
144	n/a	actual = slice.indices(length)
145	n/a	except ValueError:
146	n/a	actual = "valueerror"
147	n/a	try:
148	n/a	expected = slice_indices(slice, length)
149	n/a	except ValueError:
150	n/a	expected = "valueerror"
151	n/a	self.assertEqual(actual, expected)
152	n/a
153	n/a	if length >= 0 and slice.step != 0:
154	n/a	actual = range(*slice.indices(length))
155	n/a	expected = range(length)[slice]
156	n/a	self.assertEqual(actual, expected)
157	n/a
158	n/a	def test_indices(self):
159	n/a	self.assertEqual(slice(None ).indices(10), (0, 10, 1))
160	n/a	self.assertEqual(slice(None, None, 2).indices(10), (0, 10, 2))
161	n/a	self.assertEqual(slice(1, None, 2).indices(10), (1, 10, 2))
162	n/a	self.assertEqual(slice(None, None, -1).indices(10), (9, -1, -1))
163	n/a	self.assertEqual(slice(None, None, -2).indices(10), (9, -1, -2))
164	n/a	self.assertEqual(slice(3, None, -2).indices(10), (3, -1, -2))
165	n/a	# issue 3004 tests
166	n/a	self.assertEqual(slice(None, -9).indices(10), (0, 1, 1))
167	n/a	self.assertEqual(slice(None, -10).indices(10), (0, 0, 1))
168	n/a	self.assertEqual(slice(None, -11).indices(10), (0, 0, 1))
169	n/a	self.assertEqual(slice(None, -10, -1).indices(10), (9, 0, -1))
170	n/a	self.assertEqual(slice(None, -11, -1).indices(10), (9, -1, -1))
171	n/a	self.assertEqual(slice(None, -12, -1).indices(10), (9, -1, -1))
172	n/a	self.assertEqual(slice(None, 9).indices(10), (0, 9, 1))
173	n/a	self.assertEqual(slice(None, 10).indices(10), (0, 10, 1))
174	n/a	self.assertEqual(slice(None, 11).indices(10), (0, 10, 1))
175	n/a	self.assertEqual(slice(None, 8, -1).indices(10), (9, 8, -1))
176	n/a	self.assertEqual(slice(None, 9, -1).indices(10), (9, 9, -1))
177	n/a	self.assertEqual(slice(None, 10, -1).indices(10), (9, 9, -1))
178	n/a
179	n/a	self.assertEqual(
180	n/a	slice(-100, 100 ).indices(10),
181	n/a	slice(None).indices(10)
182	n/a	)
183	n/a	self.assertEqual(
184	n/a	slice(100, -100, -1).indices(10),
185	n/a	slice(None, None, -1).indices(10)
186	n/a	)
187	n/a	self.assertEqual(slice(-100, 100, 2).indices(10), (0, 10, 2))
188	n/a
189	n/a	self.assertEqual(list(range(10))[::sys.maxsize - 1], [0])
190	n/a
191	n/a	# Check a variety of start, stop, step and length values, including
192	n/a	# values exceeding sys.maxsize (see issue #14794).
193	n/a	vals = [None, -2100, -230, -53, -7, -1, 0, 1, 7, 53, 230, 2100]
194	n/a	lengths = [0, 1, 7, 53, 230, 2100]
195	n/a	for slice_args in itertools.product(vals, repeat=3):
196	n/a	s = slice(*slice_args)
197	n/a	for length in lengths:
198	n/a	self.check_indices(s, length)
199	n/a	self.check_indices(slice(0, 10, 1), -3)
200	n/a
201	n/a	# Negative length should raise ValueError
202	n/a	with self.assertRaises(ValueError):
203	n/a	slice(None).indices(-1)
204	n/a
205	n/a	# Zero step should raise ValueError
206	n/a	with self.assertRaises(ValueError):
207	n/a	slice(0, 10, 0).indices(5)
208	n/a
209	n/a	# Using a start, stop or step or length that can't be interpreted as an
210	n/a	# integer should give a TypeError ...
211	n/a	with self.assertRaises(TypeError):
212	n/a	slice(0.0, 10, 1).indices(5)
213	n/a	with self.assertRaises(TypeError):
214	n/a	slice(0, 10.0, 1).indices(5)
215	n/a	with self.assertRaises(TypeError):
216	n/a	slice(0, 10, 1.0).indices(5)
217	n/a	with self.assertRaises(TypeError):
218	n/a	slice(0, 10, 1).indices(5.0)
219	n/a
220	n/a	# ... but it should be fine to use a custom class that provides index.
221	n/a	self.assertEqual(slice(0, 10, 1).indices(5), (0, 5, 1))
222	n/a	self.assertEqual(slice(MyIndexable(0), 10, 1).indices(5), (0, 5, 1))
223	n/a	self.assertEqual(slice(0, MyIndexable(10), 1).indices(5), (0, 5, 1))
224	n/a	self.assertEqual(slice(0, 10, MyIndexable(1)).indices(5), (0, 5, 1))
225	n/a	self.assertEqual(slice(0, 10, 1).indices(MyIndexable(5)), (0, 5, 1))
226	n/a
227	n/a	def test_setslice_without_getslice(self):
228	n/a	tmp = []
229	n/a	class X(object):
230	n/a	def __setitem__(self, i, k):
231	n/a	tmp.append((i, k))
232	n/a
233	n/a	x = X()
234	n/a	x[1:2] = 42
235	n/a	self.assertEqual(tmp, [(slice(1, 2), 42)])
236	n/a
237	n/a	def test_pickle(self):
238	n/a	s = slice(10, 20, 3)
239	n/a	for protocol in (0,1,2):
240	n/a	t = loads(dumps(s, protocol))
241	n/a	self.assertEqual(s, t)
242	n/a	self.assertEqual(s.indices(15), t.indices(15))
243	n/a	self.assertNotEqual(id(s), id(t))
244	n/a
245	n/a	def test_cycle(self):
246	n/a	class myobj(): pass
247	n/a	o = myobj()
248	n/a	o.s = slice(o)
249	n/a	w = weakref.ref(o)
250	n/a	o = None
251	n/a	support.gc_collect()
252	n/a	self.assertIsNone(w())
253	n/a
254	n/a	if __name__ == "__main__":
255	n/a	unittest.main()