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Viewing changes to bzrlib/tests/test_counted_lock.py

Turn completion assertions into separate methods.

Many common assertions used to be expressed as arguments to the complete
method.  This makes the checks more explicit, and the code easier to read.

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bzrlib/tests/test_counted_lock.py
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# Copyright (C) 2007, 2008, 2009 Canonical Ltd
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
16
 
 
17
 
"""Tests for bzrlib.counted_lock"""
18
 
 
19
 
from bzrlib.counted_lock import CountedLock
20
 
from bzrlib.errors import (
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    LockError,
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    LockNotHeld,
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    ReadOnlyError,
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    TokenMismatch,
25
 
    )
26
 
from bzrlib.tests import TestCase
27
 
 
28
 
 
29
 
class DummyLock(object):
30
 
    """Lock that just records what's been done to it."""
31
 
 
32
 
    def __init__(self):
33
 
        self._calls = []
34
 
        self._lock_mode = None
35
 
 
36
 
    def is_locked(self):
37
 
        return self._lock_mode is not None
38
 
 
39
 
    def lock_read(self):
40
 
        self._assert_not_locked()
41
 
        self._lock_mode = 'r'
42
 
        self._calls.append('lock_read')
43
 
 
44
 
    def lock_write(self, token=None):
45
 
        if token is not None:
46
 
            if token == 'token':
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                # already held by this caller
48
 
                return 'token'
49
 
            else:
50
 
                raise TokenMismatch()
51
 
        self._assert_not_locked()
52
 
        self._lock_mode = 'w'
53
 
        self._calls.append('lock_write')
54
 
        return 'token'
55
 
 
56
 
    def unlock(self):
57
 
        self._assert_locked()
58
 
        self._lock_mode = None
59
 
        self._calls.append('unlock')
60
 
 
61
 
    def break_lock(self):
62
 
        self._lock_mode = None
63
 
        self._calls.append('break')
64
 
 
65
 
    def _assert_locked(self):
66
 
        if not self._lock_mode:
67
 
            raise LockError("%s is not locked" % (self,))
68
 
 
69
 
    def _assert_not_locked(self):
70
 
        if self._lock_mode:
71
 
            raise LockError("%s is already locked in mode %r" %
72
 
                (self, self._lock_mode))
73
 
 
74
 
    def validate_token(self, token):
75
 
        if token == 'token':
76
 
            # already held by this caller
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            return 'token'
78
 
        elif token is None:
79
 
            return
80
 
        else:
81
 
            raise TokenMismatch(token, 'token')
82
 
 
83
 
 
84
 
class TestDummyLock(TestCase):
85
 
 
86
 
    def test_lock_initially_not_held(self):
87
 
        l = DummyLock()
88
 
        self.assertFalse(l.is_locked())
89
 
 
90
 
    def test_lock_not_reentrant(self):
91
 
        # can't take the underlying lock twice
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        l = DummyLock()
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        l.lock_read()
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        self.assertRaises(LockError, l.lock_read)
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96
 
    def test_detect_underlock(self):
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        l = DummyLock()
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        self.assertRaises(LockError, l.unlock)
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100
 
    def test_basic_locking(self):
101
 
        # dummy lock works like a basic non reentrant lock
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        real_lock = DummyLock()
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        self.assertFalse(real_lock.is_locked())
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        # lock read and unlock
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        real_lock.lock_read()
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        self.assertTrue(real_lock.is_locked())
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        real_lock.unlock()
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        self.assertFalse(real_lock.is_locked())
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        # lock write and unlock
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        result = real_lock.lock_write()
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        self.assertEqual('token', result)
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        self.assertTrue(real_lock.is_locked())
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        real_lock.unlock()
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        self.assertFalse(real_lock.is_locked())
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        # check calls
116
 
        self.assertEqual(
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            ['lock_read', 'unlock', 'lock_write', 'unlock'],
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            real_lock._calls)
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120
 
    def test_break_lock(self):
121
 
        l = DummyLock()
122
 
        l.lock_write()
123
 
        l.break_lock()
124
 
        self.assertFalse(l.is_locked())
125
 
        self.assertEqual(
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            ['lock_write', 'break'],
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            l._calls)
128
 
 
129
 
 
130
 
class TestCountedLock(TestCase):
131
 
 
132
 
    def test_read_lock(self):
133
 
        # Lock and unlock a counted lock
134
 
        real_lock = DummyLock()
135
 
        l = CountedLock(real_lock)
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        self.assertFalse(l.is_locked())
137
 
        # can lock twice, although this isn't allowed on the underlying lock
138
 
        l.lock_read()
139
 
        l.lock_read()
140
 
        self.assertTrue(l.is_locked())
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        # and release
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        l.unlock()
143
 
        self.assertTrue(l.is_locked())
144
 
        l.unlock()
145
 
        self.assertFalse(l.is_locked())
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        self.assertEquals(
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            ['lock_read', 'unlock'],
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            real_lock._calls)
149
 
 
150
 
    def test_unlock_not_locked(self):
151
 
        real_lock = DummyLock()
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        l = CountedLock(real_lock)
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        self.assertRaises(LockNotHeld, l.unlock)
154
 
 
155
 
    def test_read_lock_while_write_locked(self):
156
 
        real_lock = DummyLock()
157
 
        l = CountedLock(real_lock)
158
 
        l.lock_write()
159
 
        l.lock_read()
160
 
        self.assertEquals('token', l.lock_write())
161
 
        l.unlock()
162
 
        l.unlock()
163
 
        l.unlock()
164
 
        self.assertFalse(l.is_locked())
165
 
        self.assertEquals(
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            ['lock_write', 'unlock'],
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            real_lock._calls)
168
 
 
169
 
    def test_write_lock_while_read_locked(self):
170
 
        real_lock = DummyLock()
171
 
        l = CountedLock(real_lock)
172
 
        l.lock_read()
173
 
        self.assertRaises(ReadOnlyError, l.lock_write)
174
 
        self.assertRaises(ReadOnlyError, l.lock_write)
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        l.unlock()
176
 
        self.assertFalse(l.is_locked())
177
 
        self.assertEquals(
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            ['lock_read', 'unlock'],
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            real_lock._calls)
180
 
 
181
 
    def test_write_lock_reentrant(self):
182
 
        real_lock = DummyLock()
183
 
        l = CountedLock(real_lock)
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        self.assertEqual('token', l.lock_write())
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        self.assertEqual('token', l.lock_write())
186
 
        l.unlock()
187
 
        l.unlock()
188
 
 
189
 
    def test_reenter_with_token(self):
190
 
        real_lock = DummyLock()
191
 
        l1 = CountedLock(real_lock)
192
 
        l2 = CountedLock(real_lock)
193
 
        token = l1.lock_write()
194
 
        self.assertEqual('token', token)
195
 
        # now imagine that we lost that connection, but we still have the
196
 
        # token...
197
 
        del l1
198
 
        # because we can supply the token, we can acquire the lock through
199
 
        # another instance
200
 
        self.assertTrue(real_lock.is_locked())
201
 
        self.assertFalse(l2.is_locked())
202
 
        self.assertEqual(token, l2.lock_write(token=token))
203
 
        self.assertTrue(l2.is_locked())
204
 
        self.assertTrue(real_lock.is_locked())
205
 
        l2.unlock()
206
 
        self.assertFalse(l2.is_locked())
207
 
        self.assertFalse(real_lock.is_locked())
208
 
 
209
 
    def test_break_lock(self):
210
 
        real_lock = DummyLock()
211
 
        l = CountedLock(real_lock)
212
 
        l.lock_write()
213
 
        l.lock_write()
214
 
        self.assertTrue(real_lock.is_locked())
215
 
        l.break_lock()
216
 
        self.assertFalse(l.is_locked())
217
 
        self.assertFalse(real_lock.is_locked())
218
 
 
219
 
    # TODO: test get_physical_lock_status