summaryrefslogtreecommitdiffstats
path: root/Lib/test/test_contextlib.py
blob: 015a0c51951b9f04efeabc721ca8d5216323bff9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
"""Unit tests for contextlib.py, and other context managers."""


import sys
import os
import decimal
import tempfile
import unittest
import threading
from contextlib import *  # Tests __all__
from test import support
import warnings

class ContextManagerTestCase(unittest.TestCase):

    def test_contextmanager_plain(self):
        state = []
        @contextmanager
        def woohoo():
            state.append(1)
            yield 42
            state.append(999)
        with woohoo() as x:
            self.assertEqual(state, [1])
            self.assertEqual(x, 42)
            state.append(x)
        self.assertEqual(state, [1, 42, 999])

    def test_contextmanager_finally(self):
        state = []
        @contextmanager
        def woohoo():
            state.append(1)
            try:
                yield 42
            finally:
                state.append(999)
        try:
            with woohoo() as x:
                self.assertEqual(state, [1])
                self.assertEqual(x, 42)
                state.append(x)
                raise ZeroDivisionError()
        except ZeroDivisionError:
            pass
        else:
            self.fail("Expected ZeroDivisionError")
        self.assertEqual(state, [1, 42, 999])

    def test_contextmanager_no_reraise(self):
        @contextmanager
        def whee():
            yield
        ctx = whee()
        ctx.__enter__()
        # Calling __exit__ should not result in an exception
        self.assertFalse(ctx.__exit__(TypeError, TypeError("foo"), None))

    def test_contextmanager_trap_yield_after_throw(self):
        @contextmanager
        def whoo():
            try:
                yield
            except:
                yield
        ctx = whoo()
        ctx.__enter__()
        self.assertRaises(
            RuntimeError, ctx.__exit__, TypeError, TypeError("foo"), None
        )

    def test_contextmanager_except(self):
        state = []
        @contextmanager
        def woohoo():
            state.append(1)
            try:
                yield 42
            except ZeroDivisionError as e:
                state.append(e.args[0])
                self.assertEqual(state, [1, 42, 999])
        with woohoo() as x:
            self.assertEqual(state, [1])
            self.assertEqual(x, 42)
            state.append(x)
            raise ZeroDivisionError(999)
        self.assertEqual(state, [1, 42, 999])

    def test_contextmanager_attribs(self):
        def attribs(**kw):
            def decorate(func):
                for k,v in kw.items():
                    setattr(func,k,v)
                return func
            return decorate
        @contextmanager
        @attribs(foo='bar')
        def baz(spam):
            """Whee!"""
        self.assertEqual(baz.__name__,'baz')
        self.assertEqual(baz.foo, 'bar')
        self.assertEqual(baz.__doc__, "Whee!")

class NestedTestCase(unittest.TestCase):

    # XXX This needs more work

    def test_nested(self):
        @contextmanager
        def a():
            yield 1
        @contextmanager
        def b():
            yield 2
        @contextmanager
        def c():
            yield 3
        with nested(a(), b(), c()) as (x, y, z):
            self.assertEqual(x, 1)
            self.assertEqual(y, 2)
            self.assertEqual(z, 3)

    def test_nested_cleanup(self):
        state = []
        @contextmanager
        def a():
            state.append(1)
            try:
                yield 2
            finally:
                state.append(3)
        @contextmanager
        def b():
            state.append(4)
            try:
                yield 5
            finally:
                state.append(6)
        try:
            with nested(a(), b()) as (x, y):
                state.append(x)
                state.append(y)
                1/0
        except ZeroDivisionError:
            self.assertEqual(state, [1, 4, 2, 5, 6, 3])
        else:
            self.fail("Didn't raise ZeroDivisionError")

    def test_nested_right_exception(self):
        state = []
        @contextmanager
        def a():
            yield 1
        class b(object):
            def __enter__(self):
                return 2
            def __exit__(self, *exc_info):
                try:
                    raise Exception()
                except:
                    pass
        try:
            with nested(a(), b()) as (x, y):
                1/0
        except ZeroDivisionError:
            self.assertEqual((x, y), (1, 2))
        except Exception:
            self.fail("Reraised wrong exception")
        else:
            self.fail("Didn't raise ZeroDivisionError")

    def test_nested_b_swallows(self):
        @contextmanager
        def a():
            yield
        @contextmanager
        def b():
            try:
                yield
            except:
                # Swallow the exception
                pass
        try:
            with nested(a(), b()):
                1/0
        except ZeroDivisionError:
            self.fail("Didn't swallow ZeroDivisionError")

    def test_nested_break(self):
        @contextmanager
        def a():
            yield
        state = 0
        while True:
            state += 1
            with nested(a(), a()):
                break
            state += 10
        self.assertEqual(state, 1)

    def test_nested_continue(self):
        @contextmanager
        def a():
            yield
        state = 0
        while state < 3:
            state += 1
            with nested(a(), a()):
                continue
            state += 10
        self.assertEqual(state, 3)

    def test_nested_return(self):
        @contextmanager
        def a():
            try:
                yield
            except:
                pass
        def foo():
            with nested(a(), a()):
                return 1
            return 10
        self.assertEqual(foo(), 1)

class ClosingTestCase(unittest.TestCase):

    # XXX This needs more work

    def test_closing(self):
        state = []
        class C:
            def close(self):
                state.append(1)
        x = C()
        self.assertEqual(state, [])
        with closing(x) as y:
            self.assertEqual(x, y)
        self.assertEqual(state, [1])

    def test_closing_error(self):
        state = []
        class C:
            def close(self):
                state.append(1)
        x = C()
        self.assertEqual(state, [])
        try:
            with closing(x) as y:
                self.assertEqual(x, y)
                1/0
        except ZeroDivisionError:
            self.assertEqual(state, [1])
        else:
            self.fail("Didn't raise ZeroDivisionError")

class FileContextTestCase(unittest.TestCase):

    def testWithOpen(self):
        tfn = tempfile.mktemp()
        try:
            f = None
            with open(tfn, "w") as f:
                self.assertFalse(f.closed)
                f.write("Booh\n")
            self.assertTrue(f.closed)
            f = None
            try:
                with open(tfn, "r") as f:
                    self.assertFalse(f.closed)
                    self.assertEqual(f.read(), "Booh\n")
                    1/0
            except ZeroDivisionError:
                self.assertTrue(f.closed)
            else:
                self.fail("Didn't raise ZeroDivisionError")
        finally:
            try:
                os.remove(tfn)
            except os.error:
                pass

class LockContextTestCase(unittest.TestCase):

    def boilerPlate(self, lock, locked):
        self.assertFalse(locked())
        with lock:
            self.assertTrue(locked())
        self.assertFalse(locked())
        try:
            with lock:
                self.assertTrue(locked())
                1/0
        except ZeroDivisionError:
            self.assertFalse(locked())
        else:
            self.fail("Didn't raise ZeroDivisionError")

    def testWithLock(self):
        lock = threading.Lock()
        self.boilerPlate(lock, lock.locked)

    def testWithRLock(self):
        lock = threading.RLock()
        self.boilerPlate(lock, lock._is_owned)

    def testWithCondition(self):
        lock = threading.Condition()
        def locked():
            return lock._is_owned()
        self.boilerPlate(lock, locked)

    def testWithSemaphore(self):
        lock = threading.Semaphore()
        def locked():
            if lock.acquire(False):
                lock.release()
                return False
            else:
                return True
        self.boilerPlate(lock, locked)

    def testWithBoundedSemaphore(self):
        lock = threading.BoundedSemaphore()
        def locked():
            if lock.acquire(False):
                lock.release()
                return False
            else:
                return True
        self.boilerPlate(lock, locked)

# This is needed to make the test actually run under regrtest.py!
def test_main():
    with warnings.catch_warnings():
        warnings.simplefilter('ignore')
        support.run_unittest(__name__)

if __name__ == "__main__":
    test_main()