/brz/remove-bazaar

# Copyright (C) 2006, 2007, 2008 Canonical Ltd

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""Tests for the Repository facility that are not interface tests.

For interface tests see tests/repository_implementations/*.py.

For concrete class tests see this file, and for storage formats tests

also see this file.

"""

import md5

from stat import S_ISDIR

from StringIO import StringIO

import bzrlib

from bzrlib.errors import (NotBranchError,

                           NoSuchFile,

                           UnknownFormatError,

                           UnsupportedFormatError,

                           )

from bzrlib import graph

from bzrlib.index import GraphIndex, InMemoryGraphIndex

from bzrlib.repository import RepositoryFormat

from bzrlib.smart import server

from bzrlib.tests import (

    TestCase,

    TestCaseWithTransport,

    TestSkipped,

    test_knit,

    )

from bzrlib.transport import (

    fakenfs,

    get_transport,

    )

from bzrlib.transport.memory import MemoryServer

from bzrlib.util import bencode

from bzrlib import (

    bzrdir,

    errors,

    inventory,

    progress,

    repository,

    revision as _mod_revision,

    symbol_versioning,

    upgrade,

    workingtree,

    )

from bzrlib.repofmt import knitrepo, weaverepo, pack_repo

class TestDefaultFormat(TestCase):

    def test_get_set_default_format(self):

        old_default = bzrdir.format_registry.get('default')

        private_default = old_default().repository_format.__class__

        old_format = repository.RepositoryFormat.get_default_format()

        self.assertTrue(isinstance(old_format, private_default))

        def make_sample_bzrdir():

            my_bzrdir = bzrdir.BzrDirMetaFormat1()

            my_bzrdir.repository_format = SampleRepositoryFormat()

            return my_bzrdir

        bzrdir.format_registry.remove('default')

        bzrdir.format_registry.register('sample', make_sample_bzrdir, '')

        bzrdir.format_registry.set_default('sample')

        # creating a repository should now create an instrumented dir.

        try:

            # the default branch format is used by the meta dir format

            # which is not the default bzrdir format at this point

            dir = bzrdir.BzrDirMetaFormat1().initialize('memory:///')

            result = dir.create_repository()

            self.assertEqual(result, 'A bzr repository dir')

        finally:

            bzrdir.format_registry.remove('default')

            bzrdir.format_registry.remove('sample')

            bzrdir.format_registry.register('default', old_default, '')

        self.assertIsInstance(repository.RepositoryFormat.get_default_format(),

                              old_format.__class__)

class SampleRepositoryFormat(repository.RepositoryFormat):

    """A sample format

    this format is initializable, unsupported to aid in testing the 

    open and open(unsupported=True) routines.

    """

    def get_format_string(self):

        """See RepositoryFormat.get_format_string()."""

        return "Sample .bzr repository format."

    def initialize(self, a_bzrdir, shared=False):

        """Initialize a repository in a BzrDir"""

        t = a_bzrdir.get_repository_transport(self)

        t.put_bytes('format', self.get_format_string())

        return 'A bzr repository dir'

    def is_supported(self):

        return False

    def open(self, a_bzrdir, _found=False):

        return "opened repository."

class TestRepositoryFormat(TestCaseWithTransport):

    """Tests for the Repository format detection used by the bzr meta dir facility.BzrBranchFormat facility."""

    def test_find_format(self):

        # is the right format object found for a repository?

        # create a branch with a few known format objects.

        # this is not quite the same as 

        self.build_tree(["foo/", "bar/"])

        def check_format(format, url):

            dir = format._matchingbzrdir.initialize(url)

            format.initialize(dir)

            t = get_transport(url)

            found_format = repository.RepositoryFormat.find_format(dir)

            self.failUnless(isinstance(found_format, format.__class__))

        check_format(weaverepo.RepositoryFormat7(), "bar")

    def test_find_format_no_repository(self):

        dir = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        self.assertRaises(errors.NoRepositoryPresent,

                          repository.RepositoryFormat.find_format,

                          dir)

    def test_find_format_unknown_format(self):

        dir = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        SampleRepositoryFormat().initialize(dir)

        self.assertRaises(UnknownFormatError,

                          repository.RepositoryFormat.find_format,

                          dir)

    def test_register_unregister_format(self):

        format = SampleRepositoryFormat()

        # make a control dir

        dir = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        # make a repo

        format.initialize(dir)

        # register a format for it.

        repository.RepositoryFormat.register_format(format)

        # which repository.Open will refuse (not supported)

        self.assertRaises(UnsupportedFormatError, repository.Repository.open, self.get_url())

        # but open(unsupported) will work

        self.assertEqual(format.open(dir), "opened repository.")

        # unregister the format

        repository.RepositoryFormat.unregister_format(format)

class TestFormat6(TestCaseWithTransport):

    def test_attribute__fetch_order(self):

        """Weaves need topological data insertion."""

        control = bzrdir.BzrDirFormat6().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat6().initialize(control)

        self.assertEqual('topological', repo._fetch_order)

    def test_attribute__fetch_uses_deltas(self):

        """Weaves do not reuse deltas."""

        control = bzrdir.BzrDirFormat6().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat6().initialize(control)

        self.assertEqual(False, repo._fetch_uses_deltas)

    def test_attribute__fetch_reconcile(self):

        """Weave repositories need a reconcile after fetch."""

        control = bzrdir.BzrDirFormat6().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat6().initialize(control)

        self.assertEqual(True, repo._fetch_reconcile)

    def test_no_ancestry_weave(self):

        control = bzrdir.BzrDirFormat6().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat6().initialize(control)

        # We no longer need to create the ancestry.weave file

        # since it is *never* used.

        self.assertRaises(NoSuchFile,

                          control.transport.get,

                          'ancestry.weave')

    def test_supports_external_lookups(self):

        control = bzrdir.BzrDirFormat6().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat6().initialize(control)

        self.assertFalse(repo._format.supports_external_lookups)

class TestFormat7(TestCaseWithTransport):

    def test_attribute__fetch_order(self):

        """Weaves need topological data insertion."""

        control = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat7().initialize(control)

        self.assertEqual('topological', repo._fetch_order)

    def test_attribute__fetch_uses_deltas(self):

        """Weaves do not reuse deltas."""

        control = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat7().initialize(control)

        self.assertEqual(False, repo._fetch_uses_deltas)

    def test_attribute__fetch_reconcile(self):

        """Weave repositories need a reconcile after fetch."""

        control = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat7().initialize(control)

        self.assertEqual(True, repo._fetch_reconcile)

    def test_disk_layout(self):

        control = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat7().initialize(control)

        # in case of side effects of locking.

        repo.lock_write()

        repo.unlock()

        # we want:

        # format 'Bazaar-NG Repository format 7'

        # lock ''

        # inventory.weave == empty_weave

        # empty revision-store directory

        # empty weaves directory

        t = control.get_repository_transport(None)

        self.assertEqualDiff('Bazaar-NG Repository format 7',

                             t.get('format').read())

        self.assertTrue(S_ISDIR(t.stat('revision-store').st_mode))

        self.assertTrue(S_ISDIR(t.stat('weaves').st_mode))

        self.assertEqualDiff('# bzr weave file v5\n'

                             'w\n'

                             'W\n',

                             t.get('inventory.weave').read())

        # Creating a file with id Foo:Bar results in a non-escaped file name on

        # disk.

        control.create_branch()

        tree = control.create_workingtree()

        tree.add(['foo'], ['Foo:Bar'], ['file'])

        tree.put_file_bytes_non_atomic('Foo:Bar', 'content\n')

        tree.commit('first post', rev_id='first')

        self.assertEqualDiff(

            '# bzr weave file v5\n'

            'i\n'

            '1 7fe70820e08a1aac0ef224d9c66ab66831cc4ab1\n'

            'n first\n'

            '\n'

            'w\n'

            '{ 0\n'

            '. content\n'

            '}\n'

            'W\n',

            t.get('weaves/74/Foo%3ABar.weave').read())

    def test_shared_disk_layout(self):

        control = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat7().initialize(control, shared=True)

        # we want:

        # format 'Bazaar-NG Repository format 7'

        # inventory.weave == empty_weave

        # empty revision-store directory

        # empty weaves directory

        # a 'shared-storage' marker file.

        # lock is not present when unlocked

        t = control.get_repository_transport(None)

        self.assertEqualDiff('Bazaar-NG Repository format 7',

                             t.get('format').read())

        self.assertEqualDiff('', t.get('shared-storage').read())

        self.assertTrue(S_ISDIR(t.stat('revision-store').st_mode))

        self.assertTrue(S_ISDIR(t.stat('weaves').st_mode))

        self.assertEqualDiff('# bzr weave file v5\n'

                             'w\n'

                             'W\n',

                             t.get('inventory.weave').read())

        self.assertFalse(t.has('branch-lock'))

    def test_creates_lockdir(self):

        """Make sure it appears to be controlled by a LockDir existence"""

        control = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat7().initialize(control, shared=True)

        t = control.get_repository_transport(None)

        # TODO: Should check there is a 'lock' toplevel directory, 

        # regardless of contents

        self.assertFalse(t.has('lock/held/info'))

        repo.lock_write()

        try:

            self.assertTrue(t.has('lock/held/info'))

        finally:

            # unlock so we don't get a warning about failing to do so

            repo.unlock()

    def test_uses_lockdir(self):

        """repo format 7 actually locks on lockdir"""

        base_url = self.get_url()

        control = bzrdir.BzrDirMetaFormat1().initialize(base_url)

        repo = weaverepo.RepositoryFormat7().initialize(control, shared=True)

        t = control.get_repository_transport(None)

        repo.lock_write()

        repo.unlock()

        del repo

        # make sure the same lock is created by opening it

        repo = repository.Repository.open(base_url)

        repo.lock_write()

        self.assertTrue(t.has('lock/held/info'))

        repo.unlock()

        self.assertFalse(t.has('lock/held/info'))

    def test_shared_no_tree_disk_layout(self):

        control = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat7().initialize(control, shared=True)

        repo.set_make_working_trees(False)

        # we want:

        # format 'Bazaar-NG Repository format 7'

        # lock ''

        # inventory.weave == empty_weave

        # empty revision-store directory

        # empty weaves directory

        # a 'shared-storage' marker file.

        t = control.get_repository_transport(None)

        self.assertEqualDiff('Bazaar-NG Repository format 7',

                             t.get('format').read())

        ## self.assertEqualDiff('', t.get('lock').read())

        self.assertEqualDiff('', t.get('shared-storage').read())

        self.assertEqualDiff('', t.get('no-working-trees').read())

        repo.set_make_working_trees(True)

        self.assertFalse(t.has('no-working-trees'))

        self.assertTrue(S_ISDIR(t.stat('revision-store').st_mode))

        self.assertTrue(S_ISDIR(t.stat('weaves').st_mode))

        self.assertEqualDiff('# bzr weave file v5\n'

                             'w\n'

                             'W\n',

                             t.get('inventory.weave').read())

    def test_supports_external_lookups(self):

        control = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        repo = weaverepo.RepositoryFormat7().initialize(control)

        self.assertFalse(repo._format.supports_external_lookups)

class TestFormatKnit1(TestCaseWithTransport):

    def test_attribute__fetch_order(self):

        """Knits need topological data insertion."""

        repo = self.make_repository('.',

                format=bzrdir.format_registry.get('knit')())

        self.assertEqual('topological', repo._fetch_order)

    def test_attribute__fetch_uses_deltas(self):

        """Knits reuse deltas."""

        repo = self.make_repository('.',

                format=bzrdir.format_registry.get('knit')())

        self.assertEqual(True, repo._fetch_uses_deltas)

    def test_disk_layout(self):

        control = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        repo = knitrepo.RepositoryFormatKnit1().initialize(control)

        # in case of side effects of locking.

        repo.lock_write()

        repo.unlock()

        # we want:

        # format 'Bazaar-NG Knit Repository Format 1'

        # lock: is a directory

        # inventory.weave == empty_weave

        # empty revision-store directory

        # empty weaves directory

        t = control.get_repository_transport(None)

        self.assertEqualDiff('Bazaar-NG Knit Repository Format 1',

                             t.get('format').read())

        # XXX: no locks left when unlocked at the moment

        # self.assertEqualDiff('', t.get('lock').read())

        self.assertTrue(S_ISDIR(t.stat('knits').st_mode))

        self.check_knits(t)

        # Check per-file knits.

        branch = control.create_branch()

        tree = control.create_workingtree()

        tree.add(['foo'], ['Nasty-IdC:'], ['file'])

        tree.put_file_bytes_non_atomic('Nasty-IdC:', '')

        tree.commit('1st post', rev_id='foo')

        self.assertHasKnit(t, 'knits/e8/%254easty-%2549d%2543%253a',

            '\nfoo fulltext 0 81  :')

    def assertHasKnit(self, t, knit_name, extra_content=''):

        """Assert that knit_name exists on t."""

        self.assertEqualDiff('# bzr knit index 8\n' + extra_content,

                             t.get(knit_name + '.kndx').read())

    def check_knits(self, t):

        """check knit content for a repository."""

        self.assertHasKnit(t, 'inventory')

        self.assertHasKnit(t, 'revisions')

        self.assertHasKnit(t, 'signatures')

    def test_shared_disk_layout(self):

        control = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        repo = knitrepo.RepositoryFormatKnit1().initialize(control, shared=True)

        # we want:

        # format 'Bazaar-NG Knit Repository Format 1'

        # lock: is a directory

        # inventory.weave == empty_weave

        # empty revision-store directory

        # empty weaves directory

        # a 'shared-storage' marker file.

        t = control.get_repository_transport(None)

        self.assertEqualDiff('Bazaar-NG Knit Repository Format 1',

                             t.get('format').read())

        # XXX: no locks left when unlocked at the moment

        # self.assertEqualDiff('', t.get('lock').read())

        self.assertEqualDiff('', t.get('shared-storage').read())

        self.assertTrue(S_ISDIR(t.stat('knits').st_mode))

        self.check_knits(t)

    def test_shared_no_tree_disk_layout(self):

        control = bzrdir.BzrDirMetaFormat1().initialize(self.get_url())

        repo = knitrepo.RepositoryFormatKnit1().initialize(control, shared=True)

        repo.set_make_working_trees(False)

        # we want:

        # format 'Bazaar-NG Knit Repository Format 1'

        # lock ''

        # inventory.weave == empty_weave

        # empty revision-store directory

        # empty weaves directory

        # a 'shared-storage' marker file.

        t = control.get_repository_transport(None)

        self.assertEqualDiff('Bazaar-NG Knit Repository Format 1',

                             t.get('format').read())

        # XXX: no locks left when unlocked at the moment

        # self.assertEqualDiff('', t.get('lock').read())

        self.assertEqualDiff('', t.get('shared-storage').read())

        self.assertEqualDiff('', t.get('no-working-trees').read())

        repo.set_make_working_trees(True)

        self.assertFalse(t.has('no-working-trees'))

        self.assertTrue(S_ISDIR(t.stat('knits').st_mode))

        self.check_knits(t)

    def test_deserialise_sets_root_revision(self):

        """We must have a inventory.root.revision

        Old versions of the XML5 serializer did not set the revision_id for

        the whole inventory. So we grab the one from the expected text. Which

        is valid when the api is not being abused.

        """

        repo = self.make_repository('.',

                format=bzrdir.format_registry.get('knit')())

        inv_xml = '<inventory format="5">\n</inventory>\n'

        inv = repo.deserialise_inventory('test-rev-id', inv_xml)

        self.assertEqual('test-rev-id', inv.root.revision)

    def test_deserialise_uses_global_revision_id(self):

        """If it is set, then we re-use the global revision id"""

        repo = self.make_repository('.',

                format=bzrdir.format_registry.get('knit')())

        inv_xml = ('<inventory format="5" revision_id="other-rev-id">\n'

                   '</inventory>\n')

        # Arguably, the deserialise_inventory should detect a mismatch, and

        # raise an error, rather than silently using one revision_id over the

        # other.

        self.assertRaises(AssertionError, repo.deserialise_inventory,

            'test-rev-id', inv_xml)

        inv = repo.deserialise_inventory('other-rev-id', inv_xml)

        self.assertEqual('other-rev-id', inv.root.revision)

    def test_supports_external_lookups(self):

        repo = self.make_repository('.',

                format=bzrdir.format_registry.get('knit')())

        self.assertFalse(repo._format.supports_external_lookups)

class DummyRepository(object):

    """A dummy repository for testing."""

    _serializer = None

    def supports_rich_root(self):

        return False

class InterDummy(repository.InterRepository):

    """An inter-repository optimised code path for DummyRepository.

    This is for use during testing where we use DummyRepository as repositories

    so that none of the default regsitered inter-repository classes will

    MATCH.

    """

    @staticmethod

    def is_compatible(repo_source, repo_target):

        """InterDummy is compatible with DummyRepository."""

        return (isinstance(repo_source, DummyRepository) and 

            isinstance(repo_target, DummyRepository))

class TestInterRepository(TestCaseWithTransport):

    def test_get_default_inter_repository(self):

        # test that the InterRepository.get(repo_a, repo_b) probes

        # for a inter_repo class where is_compatible(repo_a, repo_b) returns

        # true and returns a default inter_repo otherwise.

        # This also tests that the default registered optimised interrepository

        # classes do not barf inappropriately when a surprising repository type

        # is handed to them.

        dummy_a = DummyRepository()

        dummy_b = DummyRepository()

        self.assertGetsDefaultInterRepository(dummy_a, dummy_b)

    def assertGetsDefaultInterRepository(self, repo_a, repo_b):

        """Asserts that InterRepository.get(repo_a, repo_b) -> the default.

        The effective default is now InterSameDataRepository because there is

        no actual sane default in the presence of incompatible data models.

        """

        inter_repo = repository.InterRepository.get(repo_a, repo_b)

        self.assertEqual(repository.InterSameDataRepository,

                         inter_repo.__class__)

        self.assertEqual(repo_a, inter_repo.source)

        self.assertEqual(repo_b, inter_repo.target)

    def test_register_inter_repository_class(self):

        # test that a optimised code path provider - a

        # InterRepository subclass can be registered and unregistered

        # and that it is correctly selected when given a repository

        # pair that it returns true on for the is_compatible static method

        # check

        dummy_a = DummyRepository()

        dummy_b = DummyRepository()

        repo = self.make_repository('.')

        # hack dummies to look like repo somewhat.

        dummy_a._serializer = repo._serializer

        dummy_b._serializer = repo._serializer

        repository.InterRepository.register_optimiser(InterDummy)

        try:

            # we should get the default for something InterDummy returns False

            # to

            self.assertFalse(InterDummy.is_compatible(dummy_a, repo))

            self.assertGetsDefaultInterRepository(dummy_a, repo)

            # and we should get an InterDummy for a pair it 'likes'

            self.assertTrue(InterDummy.is_compatible(dummy_a, dummy_b))

            inter_repo = repository.InterRepository.get(dummy_a, dummy_b)

            self.assertEqual(InterDummy, inter_repo.__class__)

            self.assertEqual(dummy_a, inter_repo.source)

            self.assertEqual(dummy_b, inter_repo.target)

        finally:

            repository.InterRepository.unregister_optimiser(InterDummy)

        # now we should get the default InterRepository object again.

        self.assertGetsDefaultInterRepository(dummy_a, dummy_b)

class TestInterWeaveRepo(TestCaseWithTransport):

    def test_is_compatible_and_registered(self):

        # InterWeaveRepo is compatible when either side

        # is a format 5/6/7 branch

        from bzrlib.repofmt import knitrepo, weaverepo

        formats = [weaverepo.RepositoryFormat5(),

                   weaverepo.RepositoryFormat6(),

                   weaverepo.RepositoryFormat7()]

        incompatible_formats = [weaverepo.RepositoryFormat4(),

                                knitrepo.RepositoryFormatKnit1(),

                                ]

        repo_a = self.make_repository('a')

        repo_b = self.make_repository('b')

        is_compatible = repository.InterWeaveRepo.is_compatible

        for source in incompatible_formats:

            # force incompatible left then right

            repo_a._format = source

            repo_b._format = formats[0]

            self.assertFalse(is_compatible(repo_a, repo_b))

            self.assertFalse(is_compatible(repo_b, repo_a))

        for source in formats:

            repo_a._format = source

            for target in formats:

                repo_b._format = target

                self.assertTrue(is_compatible(repo_a, repo_b))

        self.assertEqual(repository.InterWeaveRepo,

                         repository.InterRepository.get(repo_a,

                                                        repo_b).__class__)

class TestRepositoryConverter(TestCaseWithTransport):

    def test_convert_empty(self):

        t = get_transport(self.get_url('.'))

        t.mkdir('repository')

        repo_dir = bzrdir.BzrDirMetaFormat1().initialize('repository')

        repo = weaverepo.RepositoryFormat7().initialize(repo_dir)

        target_format = knitrepo.RepositoryFormatKnit1()

        converter = repository.CopyConverter(target_format)

        pb = bzrlib.ui.ui_factory.nested_progress_bar()

        try:

            converter.convert(repo, pb)

        finally:

            pb.finished()

        repo = repo_dir.open_repository()

        self.assertTrue(isinstance(target_format, repo._format.__class__))

class TestMisc(TestCase):

    def test_unescape_xml(self):

        """We get some kind of error when malformed entities are passed"""

        self.assertRaises(KeyError, repository._unescape_xml, 'foo&bar;') 

class TestRepositoryFormatKnit3(TestCaseWithTransport):

    def test_attribute__fetch_order(self):

        """Knits need topological data insertion."""

        format = bzrdir.BzrDirMetaFormat1()

        format.repository_format = knitrepo.RepositoryFormatKnit3()

        repo = self.make_repository('.', format=format)

        self.assertEqual('topological', repo._fetch_order)

    def test_attribute__fetch_uses_deltas(self):

        """Knits reuse deltas."""

        format = bzrdir.BzrDirMetaFormat1()

        format.repository_format = knitrepo.RepositoryFormatKnit3()

        repo = self.make_repository('.', format=format)

        self.assertEqual(True, repo._fetch_uses_deltas)

    def test_convert(self):

        """Ensure the upgrade adds weaves for roots"""

        format = bzrdir.BzrDirMetaFormat1()

        format.repository_format = knitrepo.RepositoryFormatKnit1()

        tree = self.make_branch_and_tree('.', format)

        tree.commit("Dull commit", rev_id="dull")

        revision_tree = tree.branch.repository.revision_tree('dull')

        revision_tree.lock_read()

        try:

            self.assertRaises(errors.NoSuchFile, revision_tree.get_file_lines,

                revision_tree.inventory.root.file_id)

        finally:

            revision_tree.unlock()

        format = bzrdir.BzrDirMetaFormat1()

        format.repository_format = knitrepo.RepositoryFormatKnit3()

        upgrade.Convert('.', format)

        tree = workingtree.WorkingTree.open('.')

        revision_tree = tree.branch.repository.revision_tree('dull')