~bzr-pqm/bzr/bzr.dev

1540.3.23 by Martin Pool
Allow urls like http+pycurl://host/ to use a particular impl
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# Copyright (C) 2004, 2005, 2006 by Canonical Ltd
1887.1.1 by Adeodato Simó
Do not separate paragraphs in the copyright statement with blank lines,
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#
907.1.48 by John Arbash Meinel
Updated LocalTransport by passing it through the transport_test suite, and got it to pass.
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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.
1887.1.1 by Adeodato Simó
Do not separate paragraphs in the copyright statement with blank lines,
7
#
907.1.48 by John Arbash Meinel
Updated LocalTransport by passing it through the transport_test suite, and got it to pass.
8
# This program is distributed in the hope that it will be useful,
9
# but WITHOUT ANY WARRANTY; without even the implied warranty of
10
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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# GNU General Public License for more details.
1887.1.1 by Adeodato Simó
Do not separate paragraphs in the copyright statement with blank lines,
12
#
907.1.48 by John Arbash Meinel
Updated LocalTransport by passing it through the transport_test suite, and got it to pass.
13
# You should have received a copy of the GNU General Public License
14
# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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1185.11.22 by John Arbash Meinel
Major refactoring of testtransport.
18
import os
1185.58.2 by John Arbash Meinel
Added mode to the appropriate transport functions, and tests to make sure they work.
19
import sys
1185.58.4 by John Arbash Meinel
Added permission checking to Branch, and propogated that change into the stores.
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import stat
1185.11.22 by John Arbash Meinel
Major refactoring of testtransport.
21
from cStringIO import StringIO
1442.1.44 by Robert Collins
Many transport related tweaks:
22
1558.10.2 by Robert Collins
Refactor the FakeNFS support into a TransportDecorator.
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import bzrlib
1185.50.13 by John Arbash Meinel
Expanded the Transport test suite. Including delete, copy, move, etc. Updated SftpTransport to conform.
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from bzrlib.errors import (NoSuchFile, FileExists,
1540.3.8 by Martin Pool
Some support for falling back between transport implementations.
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                           TransportNotPossible,
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                           ConnectionError,
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                           DependencyNotPresent,
1843.1.1 by John Arbash Meinel
Update get_transport to raise a nicer error which includes dependency info
28
                           UnsupportedProtocol,
1540.3.8 by Martin Pool
Some support for falling back between transport implementations.
29
                           )
1558.10.2 by Robert Collins
Refactor the FakeNFS support into a TransportDecorator.
30
from bzrlib.tests import TestCase, TestCaseInTempDir
1864.5.9 by John Arbash Meinel
Switch to returning an object to make the api more understandable.
31
from bzrlib.transport import (_CoalescedOffset,
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                              _get_protocol_handlers,
1530.1.11 by Robert Collins
Push the transport permutations list into each transport module allowing for automatic testing of new modules that are registered as transports.
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                              _get_transport_modules,
1534.4.9 by Robert Collins
Add a readonly decorator for transports.
34
                              get_transport,
1530.1.11 by Robert Collins
Push the transport permutations list into each transport module allowing for automatic testing of new modules that are registered as transports.
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                              register_lazy_transport,
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                              _set_protocol_handlers,
1540.3.8 by Martin Pool
Some support for falling back between transport implementations.
37
                              Transport,
1530.1.11 by Robert Collins
Push the transport permutations list into each transport module allowing for automatic testing of new modules that are registered as transports.
38
                              )
1540.3.6 by Martin Pool
[merge] update from bzr.dev
39
from bzrlib.transport.memory import MemoryTransport
1540.3.8 by Martin Pool
Some support for falling back between transport implementations.
40
from bzrlib.transport.local import LocalTransport
1185.58.2 by John Arbash Meinel
Added mode to the appropriate transport functions, and tests to make sure they work.
41
42
1185.58.3 by John Arbash Meinel
code cleanup
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class TestTransport(TestCase):
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    """Test the non transport-concrete class functionality."""
45
1530.1.11 by Robert Collins
Push the transport permutations list into each transport module allowing for automatic testing of new modules that are registered as transports.
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    def test__get_set_protocol_handlers(self):
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        handlers = _get_protocol_handlers()
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        self.assertNotEqual({}, handlers)
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        try:
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            _set_protocol_handlers({})
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            self.assertEqual({}, _get_protocol_handlers())
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        finally:
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            _set_protocol_handlers(handlers)
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55
    def test_get_transport_modules(self):
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        handlers = _get_protocol_handlers()
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        class SampleHandler(object):
58
            """I exist, isnt that enough?"""
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        try:
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            my_handlers = {}
61
            _set_protocol_handlers(my_handlers)
62
            register_lazy_transport('foo', 'bzrlib.tests.test_transport', 'TestTransport.SampleHandler')
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            register_lazy_transport('bar', 'bzrlib.tests.test_transport', 'TestTransport.SampleHandler')
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            self.assertEqual([SampleHandler.__module__],
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                             _get_transport_modules())
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        finally:
67
            _set_protocol_handlers(handlers)
1540.3.8 by Martin Pool
Some support for falling back between transport implementations.
68
69
    def test_transport_dependency(self):
70
        """Transport with missing dependency causes no error"""
71
        saved_handlers = _get_protocol_handlers()
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        try:
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            register_lazy_transport('foo', 'bzrlib.tests.test_transport',
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                    'BadTransportHandler')
1843.1.1 by John Arbash Meinel
Update get_transport to raise a nicer error which includes dependency info
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            try:
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                get_transport('foo://fooserver/foo')
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            except UnsupportedProtocol, e:
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                e_str = str(e)
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                self.assertEquals('Unsupported protocol'
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                                  ' for url "foo://fooserver/foo":'
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                                  ' Unable to import library "some_lib":'
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                                  ' testing missing dependency', str(e))
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            else:
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                self.fail('Did not raise UnsupportedProtocol')
1540.3.8 by Martin Pool
Some support for falling back between transport implementations.
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        finally:
1540.3.10 by Martin Pool
[broken] keep hooking pycurl into test framework
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            # restore original values
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            _set_protocol_handlers(saved_handlers)
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    def test_transport_fallback(self):
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        """Transport with missing dependency causes no error"""
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        saved_handlers = _get_protocol_handlers()
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        try:
1540.3.12 by Martin Pool
Multiple transports can be registered for any protocol, and they are
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            _set_protocol_handlers({})
1540.3.10 by Martin Pool
[broken] keep hooking pycurl into test framework
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            register_lazy_transport('foo', 'bzrlib.tests.test_transport',
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                    'BackupTransportHandler')
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            register_lazy_transport('foo', 'bzrlib.tests.test_transport',
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                    'BadTransportHandler')
98
            t = get_transport('foo://fooserver/foo')
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            self.assertTrue(isinstance(t, BackupTransportHandler))
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        finally:
1540.3.8 by Martin Pool
Some support for falling back between transport implementations.
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            _set_protocol_handlers(saved_handlers)
1864.5.1 by John Arbash Meinel
Change the readv combining algorithm for one that is easier to test.
102
103
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class TestCoalesceOffsets(TestCase):
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1864.5.3 by John Arbash Meinel
Allow collapsing ranges even if they are just 'close'
106
    def check(self, expected, offsets, limit=0, fudge=0):
1864.5.1 by John Arbash Meinel
Change the readv combining algorithm for one that is easier to test.
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        coalesce = Transport._coalesce_offsets
1864.5.9 by John Arbash Meinel
Switch to returning an object to make the api more understandable.
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        exp = [_CoalescedOffset(*x) for x in expected]
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        out = list(coalesce(offsets, limit=limit, fudge_factor=fudge))
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        self.assertEqual(exp, out)
1864.5.1 by John Arbash Meinel
Change the readv combining algorithm for one that is easier to test.
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    def test_coalesce_empty(self):
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        self.check([], [])
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    def test_coalesce_simple(self):
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        self.check([(0, 10, [(0, 10)])], [(0, 10)])
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    def test_coalesce_unrelated(self):
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        self.check([(0, 10, [(0, 10)]),
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                    (20, 10, [(0, 10)]),
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                   ], [(0, 10), (20, 10)])
1530.1.11 by Robert Collins
Push the transport permutations list into each transport module allowing for automatic testing of new modules that are registered as transports.
122
            
1864.5.1 by John Arbash Meinel
Change the readv combining algorithm for one that is easier to test.
123
    def test_coalesce_unsorted(self):
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        self.check([(20, 10, [(0, 10)]),
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                    (0, 10, [(0, 10)]),
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                   ], [(20, 10), (0, 10)])
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    def test_coalesce_nearby(self):
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        self.check([(0, 20, [(0, 10), (10, 10)])],
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                   [(0, 10), (10, 10)])
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    def test_coalesce_overlapped(self):
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        self.check([(0, 15, [(0, 10), (5, 10)])],
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                   [(0, 10), (5, 10)])
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    def test_coalesce_limit(self):
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        self.check([(10, 50, [(0, 10), (10, 10), (20, 10),
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                              (30, 10), (40, 10)]),
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                    (60, 50, [(0, 10), (10, 10), (20, 10),
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                              (30, 10), (40, 10)]),
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                   ], [(10, 10), (20, 10), (30, 10), (40, 10),
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                       (50, 10), (60, 10), (70, 10), (80, 10),
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                       (90, 10), (100, 10)],
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                    limit=5)
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    def test_coalesce_no_limit(self):
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        self.check([(10, 100, [(0, 10), (10, 10), (20, 10),
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                               (30, 10), (40, 10), (50, 10),
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                               (60, 10), (70, 10), (80, 10),
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                               (90, 10)]),
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                   ], [(10, 10), (20, 10), (30, 10), (40, 10),
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                       (50, 10), (60, 10), (70, 10), (80, 10),
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                       (90, 10), (100, 10)])
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1864.5.3 by John Arbash Meinel
Allow collapsing ranges even if they are just 'close'
155
    def test_coalesce_fudge(self):
156
        self.check([(10, 30, [(0, 10), (20, 10)]),
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                    (100, 10, [(0, 10),]),
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                   ], [(10, 10), (30, 10), (100, 10)],
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                   fudge=10
160
                  )
161
1540.3.3 by Martin Pool
Review updates of pycurl transport
162
1442.1.44 by Robert Collins
Many transport related tweaks:
163
class TestMemoryTransport(TestCase):
164
165
    def test_get_transport(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
166
        MemoryTransport()
1442.1.44 by Robert Collins
Many transport related tweaks:
167
168
    def test_clone(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
169
        transport = MemoryTransport()
170
        self.assertTrue(isinstance(transport, MemoryTransport))
1910.15.3 by Andrew Bennetts
Make memory transport pass tests.
171
        self.assertEqual("memory:///", transport.clone("/").base)
1442.1.44 by Robert Collins
Many transport related tweaks:
172
173
    def test_abspath(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
174
        transport = MemoryTransport()
1685.1.42 by John Arbash Meinel
A couple more fixes to make sure memory:/// works correctly.
175
        self.assertEqual("memory:///relpath", transport.abspath('relpath'))
1442.1.44 by Robert Collins
Many transport related tweaks:
176
1910.15.1 by Andrew Bennetts
More tests for abspath and clone behaviour
177
    def test_abspath_of_root(self):
178
        transport = MemoryTransport()
179
        self.assertEqual("memory:///", transport.base)
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        self.assertEqual("memory:///", transport.abspath('/'))
181
1442.1.44 by Robert Collins
Many transport related tweaks:
182
    def test_relpath(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
183
        transport = MemoryTransport()
1442.1.44 by Robert Collins
Many transport related tweaks:
184
185
    def test_append_and_get(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
186
        transport = MemoryTransport()
1955.3.16 by John Arbash Meinel
Switch over to Transport.append_bytes or append_files
187
        transport.append_bytes('path', 'content')
1442.1.44 by Robert Collins
Many transport related tweaks:
188
        self.assertEqual(transport.get('path').read(), 'content')
1955.3.16 by John Arbash Meinel
Switch over to Transport.append_bytes or append_files
189
        transport.append_file('path', StringIO('content'))
1442.1.44 by Robert Collins
Many transport related tweaks:
190
        self.assertEqual(transport.get('path').read(), 'contentcontent')
191
192
    def test_put_and_get(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
193
        transport = MemoryTransport()
1955.3.7 by John Arbash Meinel
Fix the deprecation warnings in the transport tests themselves
194
        transport.put_file('path', StringIO('content'))
1442.1.44 by Robert Collins
Many transport related tweaks:
195
        self.assertEqual(transport.get('path').read(), 'content')
1955.3.7 by John Arbash Meinel
Fix the deprecation warnings in the transport tests themselves
196
        transport.put_bytes('path', 'content')
1442.1.44 by Robert Collins
Many transport related tweaks:
197
        self.assertEqual(transport.get('path').read(), 'content')
198
199
    def test_append_without_dir_fails(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
200
        transport = MemoryTransport()
1442.1.44 by Robert Collins
Many transport related tweaks:
201
        self.assertRaises(NoSuchFile,
1955.3.16 by John Arbash Meinel
Switch over to Transport.append_bytes or append_files
202
                          transport.append_bytes, 'dir/path', 'content')
1442.1.44 by Robert Collins
Many transport related tweaks:
203
204
    def test_put_without_dir_fails(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
205
        transport = MemoryTransport()
1442.1.44 by Robert Collins
Many transport related tweaks:
206
        self.assertRaises(NoSuchFile,
1955.3.7 by John Arbash Meinel
Fix the deprecation warnings in the transport tests themselves
207
                          transport.put_file, 'dir/path', StringIO('content'))
1442.1.44 by Robert Collins
Many transport related tweaks:
208
209
    def test_get_missing(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
210
        transport = MemoryTransport()
1442.1.44 by Robert Collins
Many transport related tweaks:
211
        self.assertRaises(NoSuchFile, transport.get, 'foo')
212
213
    def test_has_missing(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
214
        transport = MemoryTransport()
1442.1.44 by Robert Collins
Many transport related tweaks:
215
        self.assertEquals(False, transport.has('foo'))
216
217
    def test_has_present(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
218
        transport = MemoryTransport()
1955.3.16 by John Arbash Meinel
Switch over to Transport.append_bytes or append_files
219
        transport.append_bytes('foo', 'content')
1442.1.44 by Robert Collins
Many transport related tweaks:
220
        self.assertEquals(True, transport.has('foo'))
221
222
    def test_mkdir(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
223
        transport = MemoryTransport()
1442.1.44 by Robert Collins
Many transport related tweaks:
224
        transport.mkdir('dir')
1955.3.16 by John Arbash Meinel
Switch over to Transport.append_bytes or append_files
225
        transport.append_bytes('dir/path', 'content')
1442.1.44 by Robert Collins
Many transport related tweaks:
226
        self.assertEqual(transport.get('dir/path').read(), 'content')
227
228
    def test_mkdir_missing_parent(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
229
        transport = MemoryTransport()
1442.1.44 by Robert Collins
Many transport related tweaks:
230
        self.assertRaises(NoSuchFile,
231
                          transport.mkdir, 'dir/dir')
232
233
    def test_mkdir_twice(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
234
        transport = MemoryTransport()
1442.1.44 by Robert Collins
Many transport related tweaks:
235
        transport.mkdir('dir')
236
        self.assertRaises(FileExists, transport.mkdir, 'dir')
1530.1.5 by Robert Collins
Reinstate Memory parameter tests.
237
238
    def test_parameters(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
239
        transport = MemoryTransport()
1530.1.5 by Robert Collins
Reinstate Memory parameter tests.
240
        self.assertEqual(True, transport.listable())
241
        self.assertEqual(False, transport.should_cache())
242
        self.assertEqual(False, transport.is_readonly())
1442.1.44 by Robert Collins
Many transport related tweaks:
243
244
    def test_iter_files_recursive(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
245
        transport = MemoryTransport()
1442.1.44 by Robert Collins
Many transport related tweaks:
246
        transport.mkdir('dir')
1955.3.7 by John Arbash Meinel
Fix the deprecation warnings in the transport tests themselves
247
        transport.put_bytes('dir/foo', 'content')
248
        transport.put_bytes('dir/bar', 'content')
249
        transport.put_bytes('bar', 'content')
1442.1.44 by Robert Collins
Many transport related tweaks:
250
        paths = set(transport.iter_files_recursive())
251
        self.assertEqual(set(['dir/foo', 'dir/bar', 'bar']), paths)
252
253
    def test_stat(self):
1540.3.6 by Martin Pool
[merge] update from bzr.dev
254
        transport = MemoryTransport()
1955.3.7 by John Arbash Meinel
Fix the deprecation warnings in the transport tests themselves
255
        transport.put_bytes('foo', 'content')
256
        transport.put_bytes('bar', 'phowar')
1442.1.44 by Robert Collins
Many transport related tweaks:
257
        self.assertEqual(7, transport.stat('foo').st_size)
258
        self.assertEqual(6, transport.stat('bar').st_size)
1185.35.31 by Aaron Bentley
Throw ConnectionError instead of NoSuchFile except when we get a 404
259
1534.4.9 by Robert Collins
Add a readonly decorator for transports.
260
        
261
class ReadonlyDecoratorTransportTest(TestCase):
262
    """Readonly decoration specific tests."""
263
264
    def test_local_parameters(self):
265
        import bzrlib.transport.readonly as readonly
266
        # connect to . in readonly mode
267
        transport = readonly.ReadonlyTransportDecorator('readonly+.')
268
        self.assertEqual(True, transport.listable())
269
        self.assertEqual(False, transport.should_cache())
270
        self.assertEqual(True, transport.is_readonly())
271
272
    def test_http_parameters(self):
273
        import bzrlib.transport.readonly as readonly
274
        from bzrlib.transport.http import HttpServer
275
        # connect to . via http which is not listable
276
        server = HttpServer()
277
        server.setUp()
278
        try:
279
            transport = get_transport('readonly+' + server.get_url())
280
            self.failUnless(isinstance(transport,
281
                                       readonly.ReadonlyTransportDecorator))
282
            self.assertEqual(False, transport.listable())
283
            self.assertEqual(True, transport.should_cache())
284
            self.assertEqual(True, transport.is_readonly())
285
        finally:
286
            server.tearDown()
1540.3.8 by Martin Pool
Some support for falling back between transport implementations.
287
288
1558.10.2 by Robert Collins
Refactor the FakeNFS support into a TransportDecorator.
289
class FakeNFSDecoratorTests(TestCaseInTempDir):
290
    """NFS decorator specific tests."""
291
292
    def get_nfs_transport(self, url):
293
        import bzrlib.transport.fakenfs as fakenfs
294
        # connect to url with nfs decoration
295
        return fakenfs.FakeNFSTransportDecorator('fakenfs+' + url)
296
297
    def test_local_parameters(self):
298
        # the listable, should_cache and is_readonly parameters
299
        # are not changed by the fakenfs decorator
300
        transport = self.get_nfs_transport('.')
301
        self.assertEqual(True, transport.listable())
302
        self.assertEqual(False, transport.should_cache())
303
        self.assertEqual(False, transport.is_readonly())
304
305
    def test_http_parameters(self):
306
        # the listable, should_cache and is_readonly parameters
307
        # are not changed by the fakenfs decorator
308
        from bzrlib.transport.http import HttpServer
309
        # connect to . via http which is not listable
310
        server = HttpServer()
311
        server.setUp()
312
        try:
313
            transport = self.get_nfs_transport(server.get_url())
314
            self.assertIsInstance(
315
                transport, bzrlib.transport.fakenfs.FakeNFSTransportDecorator)
316
            self.assertEqual(False, transport.listable())
317
            self.assertEqual(True, transport.should_cache())
318
            self.assertEqual(True, transport.is_readonly())
319
        finally:
320
            server.tearDown()
321
322
    def test_fakenfs_server_default(self):
323
        # a FakeNFSServer() should bring up a local relpath server for itself
324
        import bzrlib.transport.fakenfs as fakenfs
325
        server = fakenfs.FakeNFSServer()
326
        server.setUp()
327
        try:
328
            # the server should be a relpath localhost server
329
            self.assertEqual(server.get_url(), 'fakenfs+.')
330
            # and we should be able to get a transport for it
331
            transport = get_transport(server.get_url())
332
            # which must be a FakeNFSTransportDecorator instance.
333
            self.assertIsInstance(
334
                transport, fakenfs.FakeNFSTransportDecorator)
335
        finally:
336
            server.tearDown()
337
338
    def test_fakenfs_rename_semantics(self):
339
        # a FakeNFS transport must mangle the way rename errors occur to
340
        # look like NFS problems.
341
        transport = self.get_nfs_transport('.')
342
        self.build_tree(['from/', 'from/foo', 'to/', 'to/bar'],
343
                        transport=transport)
344
        self.assertRaises(bzrlib.errors.ResourceBusy,
345
                          transport.rename, 'from', 'to')
346
347
1608.2.4 by Martin Pool
[broken] Add FakeFVATTransport
348
class FakeVFATDecoratorTests(TestCaseInTempDir):
349
    """Tests for simulation of VFAT restrictions"""
350
351
    def get_vfat_transport(self, url):
352
        """Return vfat-backed transport for test directory"""
353
        from bzrlib.transport.fakevfat import FakeVFATTransportDecorator
354
        return FakeVFATTransportDecorator('vfat+' + url)
355
356
    def test_transport_creation(self):
357
        from bzrlib.transport.fakevfat import FakeVFATTransportDecorator
358
        transport = self.get_vfat_transport('.')
359
        self.assertIsInstance(transport, FakeVFATTransportDecorator)
360
361
    def test_transport_mkdir(self):
362
        transport = self.get_vfat_transport('.')
363
        transport.mkdir('HELLO')
364
        self.assertTrue(transport.has('hello'))
365
        self.assertTrue(transport.has('Hello'))
366
1608.2.11 by Martin Pool
(FakeVFAT) add test for detection of invalid characters
367
    def test_forbidden_chars(self):
368
        transport = self.get_vfat_transport('.')
369
        self.assertRaises(ValueError, transport.has, "<NU>")
370
371
1540.3.8 by Martin Pool
Some support for falling back between transport implementations.
372
class BadTransportHandler(Transport):
373
    def __init__(self, base_url):
374
        raise DependencyNotPresent('some_lib', 'testing missing dependency')
375
376
377
class BackupTransportHandler(Transport):
378
    """Test transport that works as a backup for the BadTransportHandler"""
1540.3.10 by Martin Pool
[broken] keep hooking pycurl into test framework
379
    pass
1871.1.2 by Robert Collins
Reduce code duplication in transport-parameterised tests.
380
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class TestTransportImplementation(TestCaseInTempDir):
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    """Implementation verification for transports.
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    To verify a transport we need a server factory, which is a callable
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    that accepts no parameters and returns an implementation of
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    bzrlib.transport.Server.
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    That Server is then used to construct transport instances and test
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    the transport via loopback activity.
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    Currently this assumes that the Transport object is connected to the 
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    current working directory.  So that whatever is done 
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    through the transport, should show up in the working 
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    directory, and vice-versa. This is a bug, because its possible to have
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    URL schemes which provide access to something that may not be 
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    result in storage on the local disk, i.e. due to file system limits, or 
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    due to it being a database or some other non-filesystem tool.
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    This also tests to make sure that the functions work with both
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    generators and lists (assuming iter(list) is effectively a generator)
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    """
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    def setUp(self):
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        super(TestTransportImplementation, self).setUp()
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        self._server = self.transport_server()
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        self._server.setUp()
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    def tearDown(self):
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        super(TestTransportImplementation, self).tearDown()
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        self._server.tearDown()
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    def get_transport(self):
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        """Return a connected transport to the local directory."""
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        base_url = self._server.get_url()
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        # try getting the transport via the regular interface:
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        t = get_transport(base_url)
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        if not isinstance(t, self.transport_class): 
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            # we did not get the correct transport class type. Override the
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            # regular connection behaviour by direct construction.
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            t = self.transport_class(base_url)
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        return t