~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2005, 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


# TODO: Perhaps there should be an API to find out if bzr running under the
# test suite -- some plugins might want to avoid making intrusive changes if
# this is the case.  However, we want behaviour under to test to diverge as
# little as possible, so this should be used rarely if it's added at all.
# (Suggestion from j-a-meinel, 2005-11-24)

# NOTE: Some classes in here use camelCaseNaming() rather than
# underscore_naming().  That's for consistency with unittest; it's not the
# general style of bzrlib.  Please continue that consistency when adding e.g.
# new assertFoo() methods.

import atexit
import codecs
from cStringIO import StringIO
import difflib
import doctest
import errno
import logging
import os
from pprint import pformat
import random
import re
import shlex
import stat
from subprocess import Popen, PIPE
import sys
import tempfile
import threading
import time
import unittest
import warnings


from bzrlib import (
    branchbuilder,
    bzrdir,
    debug,
    errors,
    memorytree,
    osutils,
    progress,
    ui,
    urlutils,
    registry,
    workingtree,
    )
import bzrlib.branch
import bzrlib.commands
import bzrlib.timestamp
import bzrlib.export
import bzrlib.inventory
import bzrlib.iterablefile
import bzrlib.lockdir
try:
    import bzrlib.lsprof
except ImportError:
    # lsprof not available
    pass
from bzrlib.merge import merge_inner
import bzrlib.merge3
import bzrlib.plugin
import bzrlib.store
from bzrlib import symbol_versioning
from bzrlib.symbol_versioning import (
    DEPRECATED_PARAMETER,
    deprecated_function,
    deprecated_method,
    deprecated_passed,
    )
import bzrlib.trace
from bzrlib.transport import get_transport
import bzrlib.transport
from bzrlib.transport.local import LocalURLServer
from bzrlib.transport.memory import MemoryServer
from bzrlib.transport.readonly import ReadonlyServer
from bzrlib.trace import mutter, note
from bzrlib.tests import TestUtil
from bzrlib.tests.http_server import HttpServer
from bzrlib.tests.TestUtil import (
                          TestSuite,
                          TestLoader,
                          )
from bzrlib.tests.treeshape import build_tree_contents
import bzrlib.version_info_formats.format_custom
from bzrlib.workingtree import WorkingTree, WorkingTreeFormat2

# Mark this python module as being part of the implementation
# of unittest: this gives us better tracebacks where the last
# shown frame is the test code, not our assertXYZ.
__unittest = 1

default_transport = LocalURLServer


class ExtendedTestResult(unittest._TextTestResult):
    """Accepts, reports and accumulates the results of running tests.

    Compared to the unittest version this class adds support for
    profiling, benchmarking, stopping as soon as a test fails,  and
    skipping tests.  There are further-specialized subclasses for
    different types of display.

    When a test finishes, in whatever way, it calls one of the addSuccess,
    addFailure or addError classes.  These in turn may redirect to a more
    specific case for the special test results supported by our extended
    tests.

    Note that just one of these objects is fed the results from many tests.
    """

    stop_early = False
    
    def __init__(self, stream, descriptions, verbosity,
                 bench_history=None,
                 num_tests=None,
                 ):
        """Construct new TestResult.

        :param bench_history: Optionally, a writable file object to accumulate
            benchmark results.
        """
        unittest._TextTestResult.__init__(self, stream, descriptions, verbosity)
        if bench_history is not None:
            from bzrlib.version import _get_bzr_source_tree
            src_tree = _get_bzr_source_tree()
            if src_tree:
                try:
                    revision_id = src_tree.get_parent_ids()[0]
                except IndexError:
                    # XXX: if this is a brand new tree, do the same as if there
                    # is no branch.
                    revision_id = ''
            else:
                # XXX: If there's no branch, what should we do?
                revision_id = ''
            bench_history.write("--date %s %s\n" % (time.time(), revision_id))
        self._bench_history = bench_history
        self.ui = ui.ui_factory
        self.num_tests = num_tests
        self.error_count = 0
        self.failure_count = 0
        self.known_failure_count = 0
        self.skip_count = 0
        self.not_applicable_count = 0
        self.unsupported = {}
        self.count = 0
        self._overall_start_time = time.time()
    
    def _extractBenchmarkTime(self, testCase):
        """Add a benchmark time for the current test case."""
        return getattr(testCase, "_benchtime", None)
    
    def _elapsedTestTimeString(self):
        """Return a time string for the overall time the current test has taken."""
        return self._formatTime(time.time() - self._start_time)

    def _testTimeString(self, testCase):
        benchmark_time = self._extractBenchmarkTime(testCase)
        if benchmark_time is not None:
            return "%s/%s" % (
                self._formatTime(benchmark_time),
                self._elapsedTestTimeString())
        else:
            return "           %s" % self._elapsedTestTimeString()

    def _formatTime(self, seconds):
        """Format seconds as milliseconds with leading spaces."""
        # some benchmarks can take thousands of seconds to run, so we need 8
        # places
        return "%8dms" % (1000 * seconds)

    def _shortened_test_description(self, test):
        what = test.id()
        what = re.sub(r'^bzrlib\.(tests|benchmarks)\.', '', what)
        return what

    def startTest(self, test):
        unittest.TestResult.startTest(self, test)
        self.report_test_start(test)
        test.number = self.count
        self._recordTestStartTime()

    def _recordTestStartTime(self):
        """Record that a test has started."""
        self._start_time = time.time()

    def _cleanupLogFile(self, test):
        # We can only do this if we have one of our TestCases, not if
        # we have a doctest.
        setKeepLogfile = getattr(test, 'setKeepLogfile', None)
        if setKeepLogfile is not None:
            setKeepLogfile()

    def addError(self, test, err):
        """Tell result that test finished with an error.

        Called from the TestCase run() method when the test
        fails with an unexpected error.
        """
        self._testConcluded(test)
        if isinstance(err[1], TestSkipped):
            return self._addSkipped(test, err)
        elif isinstance(err[1], UnavailableFeature):
            return self.addNotSupported(test, err[1].args[0])
        else:
            unittest.TestResult.addError(self, test, err)
            self.error_count += 1
            self.report_error(test, err)
            if self.stop_early:
                self.stop()
            self._cleanupLogFile(test)

    def addFailure(self, test, err):
        """Tell result that test failed.

        Called from the TestCase run() method when the test
        fails because e.g. an assert() method failed.
        """
        self._testConcluded(test)
        if isinstance(err[1], KnownFailure):
            return self._addKnownFailure(test, err)
        else:
            unittest.TestResult.addFailure(self, test, err)
            self.failure_count += 1
            self.report_failure(test, err)
            if self.stop_early:
                self.stop()
            self._cleanupLogFile(test)

    def addSuccess(self, test):
        """Tell result that test completed successfully.

        Called from the TestCase run()
        """
        self._testConcluded(test)
        if self._bench_history is not None:
            benchmark_time = self._extractBenchmarkTime(test)
            if benchmark_time is not None:
                self._bench_history.write("%s %s\n" % (
                    self._formatTime(benchmark_time),
                    test.id()))
        self.report_success(test)
        self._cleanupLogFile(test)
        unittest.TestResult.addSuccess(self, test)
        test._log_contents = ''

    def _testConcluded(self, test):
        """Common code when a test has finished.

        Called regardless of whether it succeded, failed, etc.
        """
        pass

    def _addKnownFailure(self, test, err):
        self.known_failure_count += 1
        self.report_known_failure(test, err)

    def addNotSupported(self, test, feature):
        """The test will not be run because of a missing feature.
        """
        # this can be called in two different ways: it may be that the
        # test started running, and then raised (through addError) 
        # UnavailableFeature.  Alternatively this method can be called
        # while probing for features before running the tests; in that
        # case we will see startTest and stopTest, but the test will never
        # actually run.
        self.unsupported.setdefault(str(feature), 0)
        self.unsupported[str(feature)] += 1
        self.report_unsupported(test, feature)

    def _addSkipped(self, test, skip_excinfo):
        if isinstance(skip_excinfo[1], TestNotApplicable):
            self.not_applicable_count += 1
            self.report_not_applicable(test, skip_excinfo)
        else:
            self.skip_count += 1
            self.report_skip(test, skip_excinfo)
        try:
            test.tearDown()
        except KeyboardInterrupt:
            raise
        except:
            self.addError(test, test._exc_info())
        else:
            # seems best to treat this as success from point-of-view of unittest
            # -- it actually does nothing so it barely matters :)
            unittest.TestResult.addSuccess(self, test)
            test._log_contents = ''

    def printErrorList(self, flavour, errors):
        for test, err in errors:
            self.stream.writeln(self.separator1)
            self.stream.write("%s: " % flavour)
            self.stream.writeln(self.getDescription(test))
            if getattr(test, '_get_log', None) is not None:
                self.stream.write('\n')
                self.stream.write(
                        ('vvvv[log from %s]' % test.id()).ljust(78,'-'))
                self.stream.write('\n')
                self.stream.write(test._get_log())
                self.stream.write('\n')
                self.stream.write(
                        ('^^^^[log from %s]' % test.id()).ljust(78,'-'))
                self.stream.write('\n')
            self.stream.writeln(self.separator2)
            self.stream.writeln("%s" % err)

    def finished(self):
        pass

    def report_cleaning_up(self):
        pass

    def report_success(self, test):
        pass

    def wasStrictlySuccessful(self):
        if self.unsupported or self.known_failure_count:
            return False
        return self.wasSuccessful()


class TextTestResult(ExtendedTestResult):
    """Displays progress and results of tests in text form"""

    def __init__(self, stream, descriptions, verbosity,
                 bench_history=None,
                 num_tests=None,
                 pb=None,
                 ):
        ExtendedTestResult.__init__(self, stream, descriptions, verbosity,
            bench_history, num_tests)
        if pb is None:
            self.pb = self.ui.nested_progress_bar()
            self._supplied_pb = False
        else:
            self.pb = pb
            self._supplied_pb = True
        self.pb.show_pct = False
        self.pb.show_spinner = False
        self.pb.show_eta = False,
        self.pb.show_count = False
        self.pb.show_bar = False

    def report_starting(self):
        self.pb.update('[test 0/%d] starting...' % (self.num_tests))

    def _progress_prefix_text(self):
        # the longer this text, the less space we have to show the test
        # name...
        a = '[%d' % self.count              # total that have been run
        # tests skipped as known not to be relevant are not important enough
        # to show here
        ## if self.skip_count:
        ##     a += ', %d skip' % self.skip_count
        ## if self.known_failure_count:
        ##     a += '+%dX' % self.known_failure_count
        if self.num_tests is not None:
            a +='/%d' % self.num_tests
        a += ' in '
        runtime = time.time() - self._overall_start_time
        if runtime >= 60:
            a += '%dm%ds' % (runtime / 60, runtime % 60)
        else:
            a += '%ds' % runtime
        if self.error_count:
            a += ', %d err' % self.error_count
        if self.failure_count:
            a += ', %d fail' % self.failure_count
        if self.unsupported:
            a += ', %d missing' % len(self.unsupported)
        a += ']'
        return a

    def report_test_start(self, test):
        self.count += 1
        self.pb.update(
                self._progress_prefix_text()
                + ' ' 
                + self._shortened_test_description(test))

    def _test_description(self, test):
        return self._shortened_test_description(test)

    def report_error(self, test, err):
        self.pb.note('ERROR: %s\n    %s\n', 
            self._test_description(test),
            err[1],
            )

    def report_failure(self, test, err):
        self.pb.note('FAIL: %s\n    %s\n', 
            self._test_description(test),
            err[1],
            )

    def report_known_failure(self, test, err):
        self.pb.note('XFAIL: %s\n%s\n',
            self._test_description(test), err[1])

    def report_skip(self, test, skip_excinfo):
        pass

    def report_not_applicable(self, test, skip_excinfo):
        pass

    def report_unsupported(self, test, feature):
        """test cannot be run because feature is missing."""
                  
    def report_cleaning_up(self):
        self.pb.update('cleaning up...')

    def finished(self):
        if not self._supplied_pb:
            self.pb.finished()


class VerboseTestResult(ExtendedTestResult):
    """Produce long output, with one line per test run plus times"""

    def _ellipsize_to_right(self, a_string, final_width):
        """Truncate and pad a string, keeping the right hand side"""
        if len(a_string) > final_width:
            result = '...' + a_string[3-final_width:]
        else:
            result = a_string
        return result.ljust(final_width)

    def report_starting(self):
        self.stream.write('running %d tests...\n' % self.num_tests)

    def report_test_start(self, test):
        self.count += 1
        name = self._shortened_test_description(test)
        # width needs space for 6 char status, plus 1 for slash, plus 2 10-char
        # numbers, plus a trailing blank
        # when NUMBERED_DIRS: plus 5 chars on test number, plus 1 char on space
        self.stream.write(self._ellipsize_to_right(name,
                          osutils.terminal_width()-30))
        self.stream.flush()

    def _error_summary(self, err):
        indent = ' ' * 4
        return '%s%s' % (indent, err[1])

    def report_error(self, test, err):
        self.stream.writeln('ERROR %s\n%s'
                % (self._testTimeString(test),
                   self._error_summary(err)))

    def report_failure(self, test, err):
        self.stream.writeln(' FAIL %s\n%s'
                % (self._testTimeString(test),
                   self._error_summary(err)))

    def report_known_failure(self, test, err):
        self.stream.writeln('XFAIL %s\n%s'
                % (self._testTimeString(test),
                   self._error_summary(err)))

    def report_success(self, test):
        self.stream.writeln('   OK %s' % self._testTimeString(test))
        for bench_called, stats in getattr(test, '_benchcalls', []):
            self.stream.writeln('LSProf output for %s(%s, %s)' % bench_called)
            stats.pprint(file=self.stream)
        # flush the stream so that we get smooth output. This verbose mode is
        # used to show the output in PQM.
        self.stream.flush()

    def report_skip(self, test, skip_excinfo):
        self.stream.writeln(' SKIP %s\n%s'
                % (self._testTimeString(test),
                   self._error_summary(skip_excinfo)))

    def report_not_applicable(self, test, skip_excinfo):
        self.stream.writeln('  N/A %s\n%s'
                % (self._testTimeString(test),
                   self._error_summary(skip_excinfo)))

    def report_unsupported(self, test, feature):
        """test cannot be run because feature is missing."""
        self.stream.writeln("NODEP %s\n    The feature '%s' is not available."
                %(self._testTimeString(test), feature))


class TextTestRunner(object):
    stop_on_failure = False

    def __init__(self,
                 stream=sys.stderr,
                 descriptions=0,
                 verbosity=1,
                 bench_history=None,
                 list_only=False
                 ):
        self.stream = unittest._WritelnDecorator(stream)
        self.descriptions = descriptions
        self.verbosity = verbosity
        self._bench_history = bench_history
        self.list_only = list_only

    def run(self, test):
        "Run the given test case or test suite."
        startTime = time.time()
        if self.verbosity == 1:
            result_class = TextTestResult
        elif self.verbosity >= 2:
            result_class = VerboseTestResult
        result = result_class(self.stream,
                              self.descriptions,
                              self.verbosity,
                              bench_history=self._bench_history,
                              num_tests=test.countTestCases(),
                              )
        result.stop_early = self.stop_on_failure
        result.report_starting()
        if self.list_only:
            if self.verbosity >= 2:
                self.stream.writeln("Listing tests only ...\n")
            run = 0
            for t in iter_suite_tests(test):
                self.stream.writeln("%s" % (t.id()))
                run += 1
            actionTaken = "Listed"
        else: 
            test.run(result)
            run = result.testsRun
            actionTaken = "Ran"
        stopTime = time.time()
        timeTaken = stopTime - startTime
        result.printErrors()
        self.stream.writeln(result.separator2)
        self.stream.writeln("%s %d test%s in %.3fs" % (actionTaken,
                            run, run != 1 and "s" or "", timeTaken))
        self.stream.writeln()
        if not result.wasSuccessful():
            self.stream.write("FAILED (")
            failed, errored = map(len, (result.failures, result.errors))
            if failed:
                self.stream.write("failures=%d" % failed)
            if errored:
                if failed: self.stream.write(", ")
                self.stream.write("errors=%d" % errored)
            if result.known_failure_count:
                if failed or errored: self.stream.write(", ")
                self.stream.write("known_failure_count=%d" %
                    result.known_failure_count)
            self.stream.writeln(")")
        else:
            if result.known_failure_count:
                self.stream.writeln("OK (known_failures=%d)" %
                    result.known_failure_count)
            else:
                self.stream.writeln("OK")
        if result.skip_count > 0:
            skipped = result.skip_count
            self.stream.writeln('%d test%s skipped' %
                                (skipped, skipped != 1 and "s" or ""))
        if result.unsupported:
            for feature, count in sorted(result.unsupported.items()):
                self.stream.writeln("Missing feature '%s' skipped %d tests." %
                    (feature, count))
        result.finished()
        return result


def iter_suite_tests(suite):
    """Return all tests in a suite, recursing through nested suites"""
    for item in suite._tests:
        if isinstance(item, unittest.TestCase):
            yield item
        elif isinstance(item, unittest.TestSuite):
            for r in iter_suite_tests(item):
                yield r
        else:
            raise Exception('unknown object %r inside test suite %r'
                            % (item, suite))


class TestSkipped(Exception):
    """Indicates that a test was intentionally skipped, rather than failing."""


class TestNotApplicable(TestSkipped):
    """A test is not applicable to the situation where it was run.

    This is only normally raised by parameterized tests, if they find that 
    the instance they're constructed upon does not support one aspect 
    of its interface.
    """


class KnownFailure(AssertionError):
    """Indicates that a test failed in a precisely expected manner.

    Such failures dont block the whole test suite from passing because they are
    indicators of partially completed code or of future work. We have an
    explicit error for them so that we can ensure that they are always visible:
    KnownFailures are always shown in the output of bzr selftest.
    """


class UnavailableFeature(Exception):
    """A feature required for this test was not available.

    The feature should be used to construct the exception.
    """


class CommandFailed(Exception):
    pass


class StringIOWrapper(object):
    """A wrapper around cStringIO which just adds an encoding attribute.
    
    Internally we can check sys.stdout to see what the output encoding
    should be. However, cStringIO has no encoding attribute that we can
    set. So we wrap it instead.
    """
    encoding='ascii'
    _cstring = None

    def __init__(self, s=None):
        if s is not None:
            self.__dict__['_cstring'] = StringIO(s)
        else:
            self.__dict__['_cstring'] = StringIO()

    def __getattr__(self, name, getattr=getattr):
        return getattr(self.__dict__['_cstring'], name)

    def __setattr__(self, name, val):
        if name == 'encoding':
            self.__dict__['encoding'] = val
        else:
            return setattr(self._cstring, name, val)


class TestUIFactory(ui.CLIUIFactory):
    """A UI Factory for testing.

    Hide the progress bar but emit note()s.
    Redirect stdin.
    Allows get_password to be tested without real tty attached.
    """

    def __init__(self,
                 stdout=None,
                 stderr=None,
                 stdin=None):
        super(TestUIFactory, self).__init__()
        if stdin is not None:
            # We use a StringIOWrapper to be able to test various
            # encodings, but the user is still responsible to
            # encode the string and to set the encoding attribute
            # of StringIOWrapper.
            self.stdin = StringIOWrapper(stdin)
        if stdout is None:
            self.stdout = sys.stdout
        else:
            self.stdout = stdout
        if stderr is None:
            self.stderr = sys.stderr
        else:
            self.stderr = stderr

    def clear(self):
        """See progress.ProgressBar.clear()."""

    def clear_term(self):
        """See progress.ProgressBar.clear_term()."""

    def clear_term(self):
        """See progress.ProgressBar.clear_term()."""

    def finished(self):
        """See progress.ProgressBar.finished()."""

    def note(self, fmt_string, *args, **kwargs):
        """See progress.ProgressBar.note()."""
        self.stdout.write((fmt_string + "\n") % args)

    def progress_bar(self):
        return self

    def nested_progress_bar(self):
        return self

    def update(self, message, count=None, total=None):
        """See progress.ProgressBar.update()."""

    def get_non_echoed_password(self, prompt):
        """Get password from stdin without trying to handle the echo mode"""
        if prompt:
            self.stdout.write(prompt.encode(self.stdout.encoding, 'replace'))
        password = self.stdin.readline()
        if not password:
            raise EOFError
        if password[-1] == '\n':
            password = password[:-1]
        return password


def _report_leaked_threads():
    bzrlib.trace.warning('%s is leaking threads among %d leaking tests',
                         TestCase._first_thread_leaker_id,
                         TestCase._leaking_threads_tests)


class TestCase(unittest.TestCase):
    """Base class for bzr unit tests.
    
    Tests that need access to disk resources should subclass 
    TestCaseInTempDir not TestCase.

    Error and debug log messages are redirected from their usual
    location into a temporary file, the contents of which can be
    retrieved by _get_log().  We use a real OS file, not an in-memory object,
    so that it can also capture file IO.  When the test completes this file
    is read into memory and removed from disk.
       
    There are also convenience functions to invoke bzr's command-line
    routine, and to build and check bzr trees.
   
    In addition to the usual method of overriding tearDown(), this class also
    allows subclasses to register functions into the _cleanups list, which is
    run in order as the object is torn down.  It's less likely this will be
    accidentally overlooked.
    """

    _active_threads = None
    _leaking_threads_tests = 0
    _first_thread_leaker_id = None
    _log_file_name = None
    _log_contents = ''
    _keep_log_file = False
    # record lsprof data when performing benchmark calls.
    _gather_lsprof_in_benchmarks = False
    attrs_to_keep = ('id', '_testMethodName', '_testMethodDoc',
                     '_log_contents', '_log_file_name', '_benchtime',
                     '_TestCase__testMethodName')

    def __init__(self, methodName='testMethod'):
        super(TestCase, self).__init__(methodName)
        self._cleanups = []

    def setUp(self):
        unittest.TestCase.setUp(self)
        self._cleanEnvironment()
        self._silenceUI()
        self._startLogFile()
        self._benchcalls = []
        self._benchtime = None
        self._clear_hooks()
        self._clear_debug_flags()
        TestCase._active_threads = threading.activeCount()
        self.addCleanup(self._check_leaked_threads)

    def _check_leaked_threads(self):
        active = threading.activeCount()
        leaked_threads = active - TestCase._active_threads
        TestCase._active_threads = active
        if leaked_threads:
            TestCase._leaking_threads_tests += 1
            if TestCase._first_thread_leaker_id is None:
                TestCase._first_thread_leaker_id = self.id()
                # we're not specifically told when all tests are finished.
                # This will do. We use a function to avoid keeping a reference
                # to a TestCase object.
                atexit.register(_report_leaked_threads)

    def _clear_debug_flags(self):
        """Prevent externally set debug flags affecting tests.
        
        Tests that want to use debug flags can just set them in the
        debug_flags set during setup/teardown.
        """
        self._preserved_debug_flags = set(debug.debug_flags)
        if 'allow_debug' not in selftest_debug_flags:
            debug.debug_flags.clear()
        self.addCleanup(self._restore_debug_flags)

    def _clear_hooks(self):
        # prevent hooks affecting tests
        import bzrlib.branch
        import bzrlib.smart.client
        import bzrlib.smart.server
        self._preserved_hooks = {
            bzrlib.branch.Branch: bzrlib.branch.Branch.hooks,
            bzrlib.mutabletree.MutableTree: bzrlib.mutabletree.MutableTree.hooks,
            bzrlib.smart.client._SmartClient: bzrlib.smart.client._SmartClient.hooks,
            bzrlib.smart.server.SmartTCPServer: bzrlib.smart.server.SmartTCPServer.hooks,
            }
        self.addCleanup(self._restoreHooks)
        # reset all hooks to an empty instance of the appropriate type
        bzrlib.branch.Branch.hooks = bzrlib.branch.BranchHooks()
        bzrlib.smart.client._SmartClient.hooks = bzrlib.smart.client.SmartClientHooks()
        bzrlib.smart.server.SmartTCPServer.hooks = bzrlib.smart.server.SmartServerHooks()

    def _silenceUI(self):
        """Turn off UI for duration of test"""
        # by default the UI is off; tests can turn it on if they want it.
        saved = ui.ui_factory
        def _restore():
            ui.ui_factory = saved
        ui.ui_factory = ui.SilentUIFactory()
        self.addCleanup(_restore)

    def _ndiff_strings(self, a, b):
        """Return ndiff between two strings containing lines.
        
        A trailing newline is added if missing to make the strings
        print properly."""
        if b and b[-1] != '\n':
            b += '\n'
        if a and a[-1] != '\n':
            a += '\n'
        difflines = difflib.ndiff(a.splitlines(True),
                                  b.splitlines(True),
                                  linejunk=lambda x: False,
                                  charjunk=lambda x: False)
        return ''.join(difflines)

    def assertEqual(self, a, b, message=''):
        try:
            if a == b:
                return
        except UnicodeError, e:
            # If we can't compare without getting a UnicodeError, then
            # obviously they are different
            mutter('UnicodeError: %s', e)
        if message:
            message += '\n'
        raise AssertionError("%snot equal:\na = %s\nb = %s\n"
            % (message,
               pformat(a), pformat(b)))

    assertEquals = assertEqual

    def assertEqualDiff(self, a, b, message=None):
        """Assert two texts are equal, if not raise an exception.
        
        This is intended for use with multi-line strings where it can 
        be hard to find the differences by eye.
        """
        # TODO: perhaps override assertEquals to call this for strings?
        if a == b:
            return
        if message is None:
            message = "texts not equal:\n"
        if a == b + '\n':
            message = 'first string is missing a final newline.\n'
        if a + '\n' == b:
            message = 'second string is missing a final newline.\n'
        raise AssertionError(message +
                             self._ndiff_strings(a, b))
        
    def assertEqualMode(self, mode, mode_test):
        self.assertEqual(mode, mode_test,
                         'mode mismatch %o != %o' % (mode, mode_test))

    def assertEqualStat(self, expected, actual):
        """assert that expected and actual are the same stat result.

        :param expected: A stat result.
        :param actual: A stat result.
        :raises AssertionError: If the expected and actual stat values differ
            other than by atime.
        """
        self.assertEqual(expected.st_size, actual.st_size)
        self.assertEqual(expected.st_mtime, actual.st_mtime)
        self.assertEqual(expected.st_ctime, actual.st_ctime)
        self.assertEqual(expected.st_dev, actual.st_dev)
        self.assertEqual(expected.st_ino, actual.st_ino)
        self.assertEqual(expected.st_mode, actual.st_mode)

    def assertPositive(self, val):
        """Assert that val is greater than 0."""
        self.assertTrue(val > 0, 'expected a positive value, but got %s' % val)

    def assertNegative(self, val):
        """Assert that val is less than 0."""
        self.assertTrue(val < 0, 'expected a negative value, but got %s' % val)

    def assertStartsWith(self, s, prefix):
        if not s.startswith(prefix):
            raise AssertionError('string %r does not start with %r' % (s, prefix))

    def assertEndsWith(self, s, suffix):
        """Asserts that s ends with suffix."""
        if not s.endswith(suffix):
            raise AssertionError('string %r does not end with %r' % (s, suffix))

    def assertContainsRe(self, haystack, needle_re):
        """Assert that a contains something matching a regular expression."""
        if not re.search(needle_re, haystack):
            if '\n' in haystack or len(haystack) > 60:
                # a long string, format it in a more readable way
                raise AssertionError(
                        'pattern "%s" not found in\n"""\\\n%s"""\n'
                        % (needle_re, haystack))
            else:
                raise AssertionError('pattern "%s" not found in "%s"'
                        % (needle_re, haystack))

    def assertNotContainsRe(self, haystack, needle_re):
        """Assert that a does not match a regular expression"""
        if re.search(needle_re, haystack):
            raise AssertionError('pattern "%s" found in "%s"'
                    % (needle_re, haystack))

    def assertSubset(self, sublist, superlist):
        """Assert that every entry in sublist is present in superlist."""
        missing = set(sublist) - set(superlist)
        if len(missing) > 0:
            raise AssertionError("value(s) %r not present in container %r" %
                                 (missing, superlist))

    def assertListRaises(self, excClass, func, *args, **kwargs):
        """Fail unless excClass is raised when the iterator from func is used.
        
        Many functions can return generators this makes sure
        to wrap them in a list() call to make sure the whole generator
        is run, and that the proper exception is raised.
        """
        try:
            list(func(*args, **kwargs))
        except excClass, e:
            return e
        else:
            if getattr(excClass,'__name__', None) is not None:
                excName = excClass.__name__
            else:
                excName = str(excClass)
            raise self.failureException, "%s not raised" % excName

    def assertRaises(self, excClass, callableObj, *args, **kwargs):
        """Assert that a callable raises a particular exception.

        :param excClass: As for the except statement, this may be either an
            exception class, or a tuple of classes.
        :param callableObj: A callable, will be passed ``*args`` and
            ``**kwargs``.

        Returns the exception so that you can examine it.
        """
        try:
            callableObj(*args, **kwargs)
        except excClass, e:
            return e
        else:
            if getattr(excClass,'__name__', None) is not None:
                excName = excClass.__name__
            else:
                # probably a tuple
                excName = str(excClass)
            raise self.failureException, "%s not raised" % excName

    def assertIs(self, left, right, message=None):
        if not (left is right):
            if message is not None:
                raise AssertionError(message)
            else:
                raise AssertionError("%r is not %r." % (left, right))

    def assertIsNot(self, left, right, message=None):
        if (left is right):
            if message is not None:
                raise AssertionError(message)
            else:
                raise AssertionError("%r is %r." % (left, right))

    def assertTransportMode(self, transport, path, mode):
        """Fail if a path does not have mode mode.
        
        If modes are not supported on this transport, the assertion is ignored.
        """
        if not transport._can_roundtrip_unix_modebits():
            return
        path_stat = transport.stat(path)
        actual_mode = stat.S_IMODE(path_stat.st_mode)
        self.assertEqual(mode, actual_mode,
            'mode of %r incorrect (%o != %o)' % (path, mode, actual_mode))

    def assertIsSameRealPath(self, path1, path2):
        """Fail if path1 and path2 points to different files"""
        self.assertEqual(osutils.realpath(path1),
                         osutils.realpath(path2),
                         "apparent paths:\na = %s\nb = %s\n," % (path1, path2))

    def assertIsInstance(self, obj, kls):
        """Fail if obj is not an instance of kls"""
        if not isinstance(obj, kls):
            self.fail("%r is an instance of %s rather than %s" % (
                obj, obj.__class__, kls))

    def expectFailure(self, reason, assertion, *args, **kwargs):
        """Invoke a test, expecting it to fail for the given reason.

        This is for assertions that ought to succeed, but currently fail.
        (The failure is *expected* but not *wanted*.)  Please be very precise
        about the failure you're expecting.  If a new bug is introduced,
        AssertionError should be raised, not KnownFailure.

        Frequently, expectFailure should be followed by an opposite assertion.
        See example below.

        Intended to be used with a callable that raises AssertionError as the
        'assertion' parameter.  args and kwargs are passed to the 'assertion'.

        Raises KnownFailure if the test fails.  Raises AssertionError if the
        test succeeds.

        example usage::

          self.expectFailure('Math is broken', self.assertNotEqual, 54,
                             dynamic_val)
          self.assertEqual(42, dynamic_val)

          This means that a dynamic_val of 54 will cause the test to raise
          a KnownFailure.  Once math is fixed and the expectFailure is removed,
          only a dynamic_val of 42 will allow the test to pass.  Anything other
          than 54 or 42 will cause an AssertionError.
        """
        try:
            assertion(*args, **kwargs)
        except AssertionError:
            raise KnownFailure(reason)
        else:
            self.fail('Unexpected success.  Should have failed: %s' % reason)

    def assertFileEqual(self, content, path):
        """Fail if path does not contain 'content'."""
        self.failUnlessExists(path)
        f = file(path, 'rb')
        try:
            s = f.read()
        finally:
            f.close()
        self.assertEqualDiff(content, s)

    def failUnlessExists(self, path):
        """Fail unless path or paths, which may be abs or relative, exist."""
        if not isinstance(path, basestring):
            for p in path:
                self.failUnlessExists(p)
        else:
            self.failUnless(osutils.lexists(path),path+" does not exist")

    def failIfExists(self, path):
        """Fail if path or paths, which may be abs or relative, exist."""
        if not isinstance(path, basestring):
            for p in path:
                self.failIfExists(p)
        else:
            self.failIf(osutils.lexists(path),path+" exists")

    def _capture_deprecation_warnings(self, a_callable, *args, **kwargs):
        """A helper for callDeprecated and applyDeprecated.

        :param a_callable: A callable to call.
        :param args: The positional arguments for the callable
        :param kwargs: The keyword arguments for the callable
        :return: A tuple (warnings, result). result is the result of calling
            a_callable(``*args``, ``**kwargs``).
        """
        local_warnings = []
        def capture_warnings(msg, cls=None, stacklevel=None):
            # we've hooked into a deprecation specific callpath,
            # only deprecations should getting sent via it.
            self.assertEqual(cls, DeprecationWarning)
            local_warnings.append(msg)
        original_warning_method = symbol_versioning.warn
        symbol_versioning.set_warning_method(capture_warnings)
        try:
            result = a_callable(*args, **kwargs)
        finally:
            symbol_versioning.set_warning_method(original_warning_method)
        return (local_warnings, result)

    def applyDeprecated(self, deprecation_format, a_callable, *args, **kwargs):
        """Call a deprecated callable without warning the user.

        Note that this only captures warnings raised by symbol_versioning.warn,
        not other callers that go direct to the warning module.

        To test that a deprecated method raises an error, do something like
        this::

            self.assertRaises(errors.ReservedId,
                self.applyDeprecated,
                deprecated_in((1, 5, 0)),
                br.append_revision,
                'current:')

        :param deprecation_format: The deprecation format that the callable
            should have been deprecated with. This is the same type as the
            parameter to deprecated_method/deprecated_function. If the
            callable is not deprecated with this format, an assertion error
            will be raised.
        :param a_callable: A callable to call. This may be a bound method or
            a regular function. It will be called with ``*args`` and
            ``**kwargs``.
        :param args: The positional arguments for the callable
        :param kwargs: The keyword arguments for the callable
        :return: The result of a_callable(``*args``, ``**kwargs``)
        """
        call_warnings, result = self._capture_deprecation_warnings(a_callable,
            *args, **kwargs)
        expected_first_warning = symbol_versioning.deprecation_string(
            a_callable, deprecation_format)
        if len(call_warnings) == 0:
            self.fail("No deprecation warning generated by call to %s" %
                a_callable)
        self.assertEqual(expected_first_warning, call_warnings[0])
        return result

    def callCatchWarnings(self, fn, *args, **kw):
        """Call a callable that raises python warnings.

        The caller's responsible for examining the returned warnings.

        If the callable raises an exception, the exception is not
        caught and propagates up to the caller.  In that case, the list
        of warnings is not available.

        :returns: ([warning_object, ...], fn_result)
        """
        # XXX: This is not perfect, because it completely overrides the
        # warnings filters, and some code may depend on suppressing particular
        # warnings.  It's the easiest way to insulate ourselves from -Werror,
        # though.  -- Andrew, 20071062
        wlist = []
        def _catcher(message, category, filename, lineno, file=None, line=None):
            # despite the name, 'message' is normally(?) a Warning subclass
            # instance
            wlist.append(message)
        saved_showwarning = warnings.showwarning
        saved_filters = warnings.filters
        try:
            warnings.showwarning = _catcher
            warnings.filters = []
            result = fn(*args, **kw)
        finally:
            warnings.showwarning = saved_showwarning
            warnings.filters = saved_filters
        return wlist, result

    def callDeprecated(self, expected, callable, *args, **kwargs):
        """Assert that a callable is deprecated in a particular way.

        This is a very precise test for unusual requirements. The 
        applyDeprecated helper function is probably more suited for most tests
        as it allows you to simply specify the deprecation format being used
        and will ensure that that is issued for the function being called.

        Note that this only captures warnings raised by symbol_versioning.warn,
        not other callers that go direct to the warning module.  To catch
        general warnings, use callCatchWarnings.

        :param expected: a list of the deprecation warnings expected, in order
        :param callable: The callable to call
        :param args: The positional arguments for the callable
        :param kwargs: The keyword arguments for the callable
        """
        call_warnings, result = self._capture_deprecation_warnings(callable,
            *args, **kwargs)
        self.assertEqual(expected, call_warnings)
        return result

    def _startLogFile(self):
        """Send bzr and test log messages to a temporary file.

        The file is removed as the test is torn down.
        """
        fileno, name = tempfile.mkstemp(suffix='.log', prefix='testbzr')
        self._log_file = os.fdopen(fileno, 'w+')
        self._log_memento = bzrlib.trace.push_log_file(self._log_file)
        self._log_file_name = name
        self.addCleanup(self._finishLogFile)

    def _finishLogFile(self):
        """Finished with the log file.

        Close the file and delete it, unless setKeepLogfile was called.
        """
        if self._log_file is None:
            return
        bzrlib.trace.pop_log_file(self._log_memento)
        self._log_file.close()
        self._log_file = None
        if not self._keep_log_file:
            os.remove(self._log_file_name)
            self._log_file_name = None

    def setKeepLogfile(self):
        """Make the logfile not be deleted when _finishLogFile is called."""
        self._keep_log_file = True

    def addCleanup(self, callable, *args, **kwargs):
        """Arrange to run a callable when this case is torn down.

        Callables are run in the reverse of the order they are registered, 
        ie last-in first-out.
        """
        self._cleanups.append((callable, args, kwargs))

    def _cleanEnvironment(self):
        new_env = {
            'BZR_HOME': None, # Don't inherit BZR_HOME to all the tests.
            'HOME': os.getcwd(),
            # bzr now uses the Win32 API and doesn't rely on APPDATA, but the
            # tests do check our impls match APPDATA
            'BZR_EDITOR': None, # test_msgeditor manipulates this variable
            'BZR_EMAIL': None,
            'BZREMAIL': None, # may still be present in the environment
            'EMAIL': None,
            'BZR_PROGRESS_BAR': None,
            'BZR_LOG': None,
            # SSH Agent
            'SSH_AUTH_SOCK': None,
            # Proxies
            'http_proxy': None,
            'HTTP_PROXY': None,
            'https_proxy': None,
            'HTTPS_PROXY': None,
            'no_proxy': None,
            'NO_PROXY': None,
            'all_proxy': None,
            'ALL_PROXY': None,
            # Nobody cares about these ones AFAIK. So far at
            # least. If you do (care), please update this comment
            # -- vila 20061212
            'ftp_proxy': None,
            'FTP_PROXY': None,
            'BZR_REMOTE_PATH': None,
        }
        self.__old_env = {}
        self.addCleanup(self._restoreEnvironment)
        for name, value in new_env.iteritems():
            self._captureVar(name, value)

    def _captureVar(self, name, newvalue):
        """Set an environment variable, and reset it when finished."""
        self.__old_env[name] = osutils.set_or_unset_env(name, newvalue)

    def _restore_debug_flags(self):
        debug.debug_flags.clear()
        debug.debug_flags.update(self._preserved_debug_flags)

    def _restoreEnvironment(self):
        for name, value in self.__old_env.iteritems():
            osutils.set_or_unset_env(name, value)

    def _restoreHooks(self):
        for klass, hooks in self._preserved_hooks.items():
            setattr(klass, 'hooks', hooks)

    def knownFailure(self, reason):
        """This test has failed for some known reason."""
        raise KnownFailure(reason)

    def run(self, result=None):
        if result is None: result = self.defaultTestResult()
        for feature in getattr(self, '_test_needs_features', []):
            if not feature.available():
                result.startTest(self)
                if getattr(result, 'addNotSupported', None):
                    result.addNotSupported(self, feature)
                else:
                    result.addSuccess(self)
                result.stopTest(self)
                return
        try:
            return unittest.TestCase.run(self, result)
        finally:
            saved_attrs = {}
            absent_attr = object()
            for attr_name in self.attrs_to_keep:
                attr = getattr(self, attr_name, absent_attr)
                if attr is not absent_attr:
                    saved_attrs[attr_name] = attr
            self.__dict__ = saved_attrs

    def tearDown(self):
        self._runCleanups()
        unittest.TestCase.tearDown(self)

    def time(self, callable, *args, **kwargs):
        """Run callable and accrue the time it takes to the benchmark time.
        
        If lsprofiling is enabled (i.e. by --lsprof-time to bzr selftest) then
        this will cause lsprofile statistics to be gathered and stored in
        self._benchcalls.
        """
        if self._benchtime is None:
            self._benchtime = 0
        start = time.time()
        try:
            if not self._gather_lsprof_in_benchmarks:
                return callable(*args, **kwargs)
            else:
                # record this benchmark
                ret, stats = bzrlib.lsprof.profile(callable, *args, **kwargs)
                stats.sort()
                self._benchcalls.append(((callable, args, kwargs), stats))
                return ret
        finally:
            self._benchtime += time.time() - start

    def _runCleanups(self):
        """Run registered cleanup functions. 

        This should only be called from TestCase.tearDown.
        """
        # TODO: Perhaps this should keep running cleanups even if 
        # one of them fails?

        # Actually pop the cleanups from the list so tearDown running
        # twice is safe (this happens for skipped tests).
        while self._cleanups:
            cleanup, args, kwargs = self._cleanups.pop()
            cleanup(*args, **kwargs)

    def log(self, *args):
        mutter(*args)

    def _get_log(self, keep_log_file=False):
        """Get the log from bzrlib.trace calls from this test.

        :param keep_log_file: When True, if the log is still a file on disk
            leave it as a file on disk. When False, if the log is still a file
            on disk, the log file is deleted and the log preserved as
            self._log_contents.
        :return: A string containing the log.
        """
        # flush the log file, to get all content
        import bzrlib.trace
        bzrlib.trace._trace_file.flush()
        if self._log_contents:
            # XXX: this can hardly contain the content flushed above --vila
            # 20080128
            return self._log_contents
        if self._log_file_name is not None:
            logfile = open(self._log_file_name)
            try:
                log_contents = logfile.read()
            finally:
                logfile.close()
            if not keep_log_file:
                self._log_contents = log_contents
                try:
                    os.remove(self._log_file_name)
                except OSError, e:
                    if sys.platform == 'win32' and e.errno == errno.EACCES:
                        sys.stderr.write(('Unable to delete log file '
                                             ' %r\n' % self._log_file_name))
                    else:
                        raise
            return log_contents
        else:
            return "DELETED log file to reduce memory footprint"

    def requireFeature(self, feature):
        """This test requires a specific feature is available.

        :raises UnavailableFeature: When feature is not available.
        """
        if not feature.available():
            raise UnavailableFeature(feature)

    def _run_bzr_autosplit(self, args, retcode, encoding, stdin,
            working_dir):
        """Run bazaar command line, splitting up a string command line."""
        if isinstance(args, basestring):
            # shlex don't understand unicode strings,
            # so args should be plain string (bialix 20070906)
            args = list(shlex.split(str(args)))
        return self._run_bzr_core(args, retcode=retcode,
                encoding=encoding, stdin=stdin, working_dir=working_dir,
                )

    def _run_bzr_core(self, args, retcode, encoding, stdin,
            working_dir):
        if encoding is None:
            encoding = osutils.get_user_encoding()
        stdout = StringIOWrapper()
        stderr = StringIOWrapper()
        stdout.encoding = encoding
        stderr.encoding = encoding

        self.log('run bzr: %r', args)
        # FIXME: don't call into logging here
        handler = logging.StreamHandler(stderr)
        handler.setLevel(logging.INFO)
        logger = logging.getLogger('')
        logger.addHandler(handler)
        old_ui_factory = ui.ui_factory
        ui.ui_factory = TestUIFactory(stdin=stdin, stdout=stdout, stderr=stderr)

        cwd = None
        if working_dir is not None:
            cwd = osutils.getcwd()
            os.chdir(working_dir)

        try:
            result = self.apply_redirected(ui.ui_factory.stdin,
                stdout, stderr,
                bzrlib.commands.run_bzr_catch_user_errors,
                args)
        finally:
            logger.removeHandler(handler)
            ui.ui_factory = old_ui_factory
            if cwd is not None:
                os.chdir(cwd)

        out = stdout.getvalue()
        err = stderr.getvalue()
        if out:
            self.log('output:\n%r', out)
        if err:
            self.log('errors:\n%r', err)
        if retcode is not None:
            self.assertEquals(retcode, result,
                              message='Unexpected return code')
        return out, err

    def run_bzr(self, args, retcode=0, encoding=None, stdin=None,
                working_dir=None, error_regexes=[], output_encoding=None):
        """Invoke bzr, as if it were run from the command line.

        The argument list should not include the bzr program name - the
        first argument is normally the bzr command.  Arguments may be
        passed in three ways:

        1- A list of strings, eg ["commit", "a"].  This is recommended
        when the command contains whitespace or metacharacters, or 
        is built up at run time.

        2- A single string, eg "add a".  This is the most convenient 
        for hardcoded commands.

        This runs bzr through the interface that catches and reports
        errors, and with logging set to something approximating the
        default, so that error reporting can be checked.

        This should be the main method for tests that want to exercise the
        overall behavior of the bzr application (rather than a unit test
        or a functional test of the library.)

        This sends the stdout/stderr results into the test's log,
        where it may be useful for debugging.  See also run_captured.

        :keyword stdin: A string to be used as stdin for the command.
        :keyword retcode: The status code the command should return;
            default 0.
        :keyword working_dir: The directory to run the command in
        :keyword error_regexes: A list of expected error messages.  If
            specified they must be seen in the error output of the command.
        """
        out, err = self._run_bzr_autosplit(
            args=args,
            retcode=retcode,
            encoding=encoding,
            stdin=stdin,
            working_dir=working_dir,
            )
        for regex in error_regexes:
            self.assertContainsRe(err, regex)
        return out, err

    def run_bzr_error(self, error_regexes, *args, **kwargs):
        """Run bzr, and check that stderr contains the supplied regexes

        :param error_regexes: Sequence of regular expressions which
            must each be found in the error output. The relative ordering
            is not enforced.
        :param args: command-line arguments for bzr
        :param kwargs: Keyword arguments which are interpreted by run_bzr
            This function changes the default value of retcode to be 3,
            since in most cases this is run when you expect bzr to fail.

        :return: (out, err) The actual output of running the command (in case
            you want to do more inspection)

        Examples of use::

            # Make sure that commit is failing because there is nothing to do
            self.run_bzr_error(['no changes to commit'],
                               ['commit', '-m', 'my commit comment'])
            # Make sure --strict is handling an unknown file, rather than
            # giving us the 'nothing to do' error
            self.build_tree(['unknown'])
            self.run_bzr_error(['Commit refused because there are unknown files'],
                               ['commit', --strict', '-m', 'my commit comment'])
        """
        kwargs.setdefault('retcode', 3)
        kwargs['error_regexes'] = error_regexes
        out, err = self.run_bzr(*args, **kwargs)
        return out, err

    def run_bzr_subprocess(self, *args, **kwargs):
        """Run bzr in a subprocess for testing.

        This starts a new Python interpreter and runs bzr in there. 
        This should only be used for tests that have a justifiable need for
        this isolation: e.g. they are testing startup time, or signal
        handling, or early startup code, etc.  Subprocess code can't be 
        profiled or debugged so easily.

        :keyword retcode: The status code that is expected.  Defaults to 0.  If
            None is supplied, the status code is not checked.
        :keyword env_changes: A dictionary which lists changes to environment
            variables. A value of None will unset the env variable.
            The values must be strings. The change will only occur in the
            child, so you don't need to fix the environment after running.
        :keyword universal_newlines: Convert CRLF => LF
        :keyword allow_plugins: By default the subprocess is run with
            --no-plugins to ensure test reproducibility. Also, it is possible
            for system-wide plugins to create unexpected output on stderr,
            which can cause unnecessary test failures.
        """
        env_changes = kwargs.get('env_changes', {})
        working_dir = kwargs.get('working_dir', None)
        allow_plugins = kwargs.get('allow_plugins', False)
        if len(args) == 1:
            if isinstance(args[0], list):
                args = args[0]
            elif isinstance(args[0], basestring):
                args = list(shlex.split(args[0]))
        else:
            raise ValueError("passing varargs to run_bzr_subprocess")
        process = self.start_bzr_subprocess(args, env_changes=env_changes,
                                            working_dir=working_dir,
                                            allow_plugins=allow_plugins)
        # We distinguish between retcode=None and retcode not passed.
        supplied_retcode = kwargs.get('retcode', 0)
        return self.finish_bzr_subprocess(process, retcode=supplied_retcode,
            universal_newlines=kwargs.get('universal_newlines', False),
            process_args=args)

    def start_bzr_subprocess(self, process_args, env_changes=None,
                             skip_if_plan_to_signal=False,
                             working_dir=None,
                             allow_plugins=False):
        """Start bzr in a subprocess for testing.

        This starts a new Python interpreter and runs bzr in there.
        This should only be used for tests that have a justifiable need for
        this isolation: e.g. they are testing startup time, or signal
        handling, or early startup code, etc.  Subprocess code can't be
        profiled or debugged so easily.

        :param process_args: a list of arguments to pass to the bzr executable,
            for example ``['--version']``.
        :param env_changes: A dictionary which lists changes to environment
            variables. A value of None will unset the env variable.
            The values must be strings. The change will only occur in the
            child, so you don't need to fix the environment after running.
        :param skip_if_plan_to_signal: raise TestSkipped when true and os.kill
            is not available.
        :param allow_plugins: If False (default) pass --no-plugins to bzr.

        :returns: Popen object for the started process.
        """
        if skip_if_plan_to_signal:
            if not getattr(os, 'kill', None):
                raise TestSkipped("os.kill not available.")

        if env_changes is None:
            env_changes = {}
        old_env = {}

        def cleanup_environment():
            for env_var, value in env_changes.iteritems():
                old_env[env_var] = osutils.set_or_unset_env(env_var, value)

        def restore_environment():
            for env_var, value in old_env.iteritems():
                osutils.set_or_unset_env(env_var, value)

        bzr_path = self.get_bzr_path()

        cwd = None
        if working_dir is not None:
            cwd = osutils.getcwd()
            os.chdir(working_dir)

        try:
            # win32 subprocess doesn't support preexec_fn
            # so we will avoid using it on all platforms, just to
            # make sure the code path is used, and we don't break on win32
            cleanup_environment()
            command = [sys.executable]
            # frozen executables don't need the path to bzr
            if getattr(sys, "frozen", None) is None:
                command.append(bzr_path)
            if not allow_plugins:
                command.append('--no-plugins')
            command.extend(process_args)
            process = self._popen(command, stdin=PIPE, stdout=PIPE, stderr=PIPE)
        finally:
            restore_environment()
            if cwd is not None:
                os.chdir(cwd)

        return process

    def _popen(self, *args, **kwargs):
        """Place a call to Popen.

        Allows tests to override this method to intercept the calls made to
        Popen for introspection.
        """
        return Popen(*args, **kwargs)

    def get_bzr_path(self):
        """Return the path of the 'bzr' executable for this test suite."""
        bzr_path = os.path.dirname(os.path.dirname(bzrlib.__file__))+'/bzr'
        if not os.path.isfile(bzr_path):
            # We are probably installed. Assume sys.argv is the right file
            bzr_path = sys.argv[0]
        return bzr_path

    def finish_bzr_subprocess(self, process, retcode=0, send_signal=None,
                              universal_newlines=False, process_args=None):
        """Finish the execution of process.

        :param process: the Popen object returned from start_bzr_subprocess.
        :param retcode: The status code that is expected.  Defaults to 0.  If
            None is supplied, the status code is not checked.
        :param send_signal: an optional signal to send to the process.
        :param universal_newlines: Convert CRLF => LF
        :returns: (stdout, stderr)
        """
        if send_signal is not None:
            os.kill(process.pid, send_signal)
        out, err = process.communicate()

        if universal_newlines:
            out = out.replace('\r\n', '\n')
            err = err.replace('\r\n', '\n')

        if retcode is not None and retcode != process.returncode:
            if process_args is None:
                process_args = "(unknown args)"
            mutter('Output of bzr %s:\n%s', process_args, out)
            mutter('Error for bzr %s:\n%s', process_args, err)
            self.fail('Command bzr %s failed with retcode %s != %s'
                      % (process_args, retcode, process.returncode))
        return [out, err]

    def check_inventory_shape(self, inv, shape):
        """Compare an inventory to a list of expected names.

        Fail if they are not precisely equal.
        """
        extras = []
        shape = list(shape)             # copy
        for path, ie in inv.entries():
            name = path.replace('\\', '/')
            if ie.kind == 'directory':
                name = name + '/'
            if name in shape:
                shape.remove(name)
            else:
                extras.append(name)
        if shape:
            self.fail("expected paths not found in inventory: %r" % shape)
        if extras:
            self.fail("unexpected paths found in inventory: %r" % extras)

    def apply_redirected(self, stdin=None, stdout=None, stderr=None,
                         a_callable=None, *args, **kwargs):
        """Call callable with redirected std io pipes.

        Returns the return code."""
        if not callable(a_callable):
            raise ValueError("a_callable must be callable.")
        if stdin is None:
            stdin = StringIO("")
        if stdout is None:
            if getattr(self, "_log_file", None) is not None:
                stdout = self._log_file
            else:
                stdout = StringIO()
        if stderr is None:
            if getattr(self, "_log_file", None is not None):
                stderr = self._log_file
            else:
                stderr = StringIO()
        real_stdin = sys.stdin
        real_stdout = sys.stdout
        real_stderr = sys.stderr
        try:
            sys.stdout = stdout
            sys.stderr = stderr
            sys.stdin = stdin
            return a_callable(*args, **kwargs)
        finally:
            sys.stdout = real_stdout
            sys.stderr = real_stderr
            sys.stdin = real_stdin

    def reduceLockdirTimeout(self):
        """Reduce the default lock timeout for the duration of the test, so that
        if LockContention occurs during a test, it does so quickly.

        Tests that expect to provoke LockContention errors should call this.
        """
        orig_timeout = bzrlib.lockdir._DEFAULT_TIMEOUT_SECONDS
        def resetTimeout():
            bzrlib.lockdir._DEFAULT_TIMEOUT_SECONDS = orig_timeout
        self.addCleanup(resetTimeout)
        bzrlib.lockdir._DEFAULT_TIMEOUT_SECONDS = 0

    def make_utf8_encoded_stringio(self, encoding_type=None):
        """Return a StringIOWrapper instance, that will encode Unicode
        input to UTF-8.
        """
        if encoding_type is None:
            encoding_type = 'strict'
        sio = StringIO()
        output_encoding = 'utf-8'
        sio = codecs.getwriter(output_encoding)(sio, errors=encoding_type)
        sio.encoding = output_encoding
        return sio


class TestCaseWithMemoryTransport(TestCase):
    """Common test class for tests that do not need disk resources.

    Tests that need disk resources should derive from TestCaseWithTransport.

    TestCaseWithMemoryTransport sets the TEST_ROOT variable for all bzr tests.

    For TestCaseWithMemoryTransport the test_home_dir is set to the name of
    a directory which does not exist. This serves to help ensure test isolation
    is preserved. test_dir is set to the TEST_ROOT, as is cwd, because they
    must exist. However, TestCaseWithMemoryTransport does not offer local
    file defaults for the transport in tests, nor does it obey the command line
    override, so tests that accidentally write to the common directory should
    be rare.

    :cvar TEST_ROOT: Directory containing all temporary directories, plus
    a .bzr directory that stops us ascending higher into the filesystem.
    """

    TEST_ROOT = None
    _TEST_NAME = 'test'

    def __init__(self, methodName='runTest'):
        # allow test parameterization after test construction and before test
        # execution. Variables that the parameterizer sets need to be 
        # ones that are not set by setUp, or setUp will trash them.
        super(TestCaseWithMemoryTransport, self).__init__(methodName)
        self.vfs_transport_factory = default_transport
        self.transport_server = None
        self.transport_readonly_server = None
        self.__vfs_server = None

    def get_transport(self, relpath=None):
        """Return a writeable transport.

        This transport is for the test scratch space relative to
        "self._test_root"
        
        :param relpath: a path relative to the base url.
        """
        t = get_transport(self.get_url(relpath))
        self.assertFalse(t.is_readonly())
        return t

    def get_readonly_transport(self, relpath=None):
        """Return a readonly transport for the test scratch space
        
        This can be used to test that operations which should only need
        readonly access in fact do not try to write.

        :param relpath: a path relative to the base url.
        """
        t = get_transport(self.get_readonly_url(relpath))
        self.assertTrue(t.is_readonly())
        return t

    def create_transport_readonly_server(self):
        """Create a transport server from class defined at init.

        This is mostly a hook for daughter classes.
        """
        return self.transport_readonly_server()

    def get_readonly_server(self):
        """Get the server instance for the readonly transport

        This is useful for some tests with specific servers to do diagnostics.
        """
        if self.__readonly_server is None:
            if self.transport_readonly_server is None:
                # readonly decorator requested
                # bring up the server
                self.__readonly_server = ReadonlyServer()
                self.__readonly_server.setUp(self.get_vfs_only_server())
            else:
                self.__readonly_server = self.create_transport_readonly_server()
                self.__readonly_server.setUp(self.get_vfs_only_server())
            self.addCleanup(self.__readonly_server.tearDown)
        return self.__readonly_server

    def get_readonly_url(self, relpath=None):
        """Get a URL for the readonly transport.

        This will either be backed by '.' or a decorator to the transport 
        used by self.get_url()
        relpath provides for clients to get a path relative to the base url.
        These should only be downwards relative, not upwards.
        """
        base = self.get_readonly_server().get_url()
        return self._adjust_url(base, relpath)

    def get_vfs_only_server(self):
        """Get the vfs only read/write server instance.

        This is useful for some tests with specific servers that need
        diagnostics.

        For TestCaseWithMemoryTransport this is always a MemoryServer, and there
        is no means to override it.
        """
        if self.__vfs_server is None:
            self.__vfs_server = MemoryServer()
            self.__vfs_server.setUp()
            self.addCleanup(self.__vfs_server.tearDown)
        return self.__vfs_server

    def get_server(self):
        """Get the read/write server instance.

        This is useful for some tests with specific servers that need
        diagnostics.

        This is built from the self.transport_server factory. If that is None,
        then the self.get_vfs_server is returned.
        """
        if self.__server is None:
            if self.transport_server is None or self.transport_server is self.vfs_transport_factory:
                return self.get_vfs_only_server()
            else:
                # bring up a decorated means of access to the vfs only server.
                self.__server = self.transport_server()
                try:
                    self.__server.setUp(self.get_vfs_only_server())
                except TypeError, e:
                    # This should never happen; the try:Except here is to assist
                    # developers having to update code rather than seeing an
                    # uninformative TypeError.
                    raise Exception, "Old server API in use: %s, %s" % (self.__server, e)
            self.addCleanup(self.__server.tearDown)
        return self.__server

    def _adjust_url(self, base, relpath):
        """Get a URL (or maybe a path) for the readwrite transport.

        This will either be backed by '.' or to an equivalent non-file based
        facility.
        relpath provides for clients to get a path relative to the base url.
        These should only be downwards relative, not upwards.
        """
        if relpath is not None and relpath != '.':
            if not base.endswith('/'):
                base = base + '/'
            # XXX: Really base should be a url; we did after all call
            # get_url()!  But sometimes it's just a path (from
            # LocalAbspathServer), and it'd be wrong to append urlescaped data
            # to a non-escaped local path.
            if base.startswith('./') or base.startswith('/'):
                base += relpath
            else:
                base += urlutils.escape(relpath)
        return base

    def get_url(self, relpath=None):
        """Get a URL (or maybe a path) for the readwrite transport.

        This will either be backed by '.' or to an equivalent non-file based
        facility.
        relpath provides for clients to get a path relative to the base url.
        These should only be downwards relative, not upwards.
        """
        base = self.get_server().get_url()
        return self._adjust_url(base, relpath)

    def get_vfs_only_url(self, relpath=None):
        """Get a URL (or maybe a path for the plain old vfs transport.

        This will never be a smart protocol.  It always has all the
        capabilities of the local filesystem, but it might actually be a
        MemoryTransport or some other similar virtual filesystem.

        This is the backing transport (if any) of the server returned by
        get_url and get_readonly_url.

        :param relpath: provides for clients to get a path relative to the base
            url.  These should only be downwards relative, not upwards.
        :return: A URL
        """
        base = self.get_vfs_only_server().get_url()
        return self._adjust_url(base, relpath)

    def _create_safety_net(self):
        """Make a fake bzr directory.

        This prevents any tests propagating up onto the TEST_ROOT directory's
        real branch.
        """
        root = TestCaseWithMemoryTransport.TEST_ROOT
        bzrdir.BzrDir.create_standalone_workingtree(root)

    def _check_safety_net(self):
        """Check that the safety .bzr directory have not been touched.

        _make_test_root have created a .bzr directory to prevent tests from
        propagating. This method ensures than a test did not leaked.
        """
        root = TestCaseWithMemoryTransport.TEST_ROOT
        wt = workingtree.WorkingTree.open(root)
        last_rev = wt.last_revision()
        if last_rev != 'null:':
            # The current test have modified the /bzr directory, we need to
            # recreate a new one or all the followng tests will fail.
            # If you need to inspect its content uncomment the following line
            # import pdb; pdb.set_trace()
            _rmtree_temp_dir(root + '/.bzr')
            self._create_safety_net()
            raise AssertionError('%s/.bzr should not be modified' % root)

    def _make_test_root(self):
        if TestCaseWithMemoryTransport.TEST_ROOT is None:
            root = osutils.mkdtemp(prefix='testbzr-', suffix='.tmp')
            TestCaseWithMemoryTransport.TEST_ROOT = root

            self._create_safety_net()

            # The same directory is used by all tests, and we're not
            # specifically told when all tests are finished.  This will do.
            atexit.register(_rmtree_temp_dir, root)

        self.addCleanup(self._check_safety_net)

    def makeAndChdirToTestDir(self):
        """Create a temporary directories for this one test.
        
        This must set self.test_home_dir and self.test_dir and chdir to
        self.test_dir.
        
        For TestCaseWithMemoryTransport we chdir to the TEST_ROOT for this test.
        """
        os.chdir(TestCaseWithMemoryTransport.TEST_ROOT)
        self.test_dir = TestCaseWithMemoryTransport.TEST_ROOT
        self.test_home_dir = self.test_dir + "/MemoryTransportMissingHomeDir"
        
    def make_branch(self, relpath, format=None):
        """Create a branch on the transport at relpath."""
        repo = self.make_repository(relpath, format=format)
        return repo.bzrdir.create_branch()

    def make_bzrdir(self, relpath, format=None):
        try:
            # might be a relative or absolute path
            maybe_a_url = self.get_url(relpath)
            segments = maybe_a_url.rsplit('/', 1)
            t = get_transport(maybe_a_url)
            if len(segments) > 1 and segments[-1] not in ('', '.'):
                t.ensure_base()
            if format is None:
                format = 'default'
            if isinstance(format, basestring):
                format = bzrdir.format_registry.make_bzrdir(format)
            return format.initialize_on_transport(t)
        except errors.UninitializableFormat:
            raise TestSkipped("Format %s is not initializable." % format)

    def make_repository(self, relpath, shared=False, format=None):
        """Create a repository on our default transport at relpath.
        
        Note that relpath must be a relative path, not a full url.
        """
        # FIXME: If you create a remoterepository this returns the underlying
        # real format, which is incorrect.  Actually we should make sure that 
        # RemoteBzrDir returns a RemoteRepository.
        # maybe  mbp 20070410
        made_control = self.make_bzrdir(relpath, format=format)
        return made_control.create_repository(shared=shared)

    def make_branch_and_memory_tree(self, relpath, format=None):
        """Create a branch on the default transport and a MemoryTree for it."""
        b = self.make_branch(relpath, format=format)
        return memorytree.MemoryTree.create_on_branch(b)

    def make_branch_builder(self, relpath, format=None):
        url = self.get_url(relpath)
        tran = get_transport(url)
        return branchbuilder.BranchBuilder(get_transport(url), format=format)

    def overrideEnvironmentForTesting(self):
        os.environ['HOME'] = self.test_home_dir
        os.environ['BZR_HOME'] = self.test_home_dir
        
    def setUp(self):
        super(TestCaseWithMemoryTransport, self).setUp()
        self._make_test_root()
        _currentdir = os.getcwdu()
        def _leaveDirectory():
            os.chdir(_currentdir)
        self.addCleanup(_leaveDirectory)
        self.makeAndChdirToTestDir()
        self.overrideEnvironmentForTesting()
        self.__readonly_server = None
        self.__server = None
        self.reduceLockdirTimeout()

     
class TestCaseInTempDir(TestCaseWithMemoryTransport):
    """Derived class that runs a test within a temporary directory.

    This is useful for tests that need to create a branch, etc.

    The directory is created in a slightly complex way: for each
    Python invocation, a new temporary top-level directory is created.
    All test cases create their own directory within that.  If the
    tests complete successfully, the directory is removed.

    :ivar test_base_dir: The path of the top-level directory for this 
    test, which contains a home directory and a work directory.

    :ivar test_home_dir: An initially empty directory under test_base_dir
    which is used as $HOME for this test.

    :ivar test_dir: A directory under test_base_dir used as the current
    directory when the test proper is run.
    """

    OVERRIDE_PYTHON = 'python'

    def check_file_contents(self, filename, expect):
        self.log("check contents of file %s" % filename)
        contents = file(filename, 'r').read()
        if contents != expect:
            self.log("expected: %r" % expect)
            self.log("actually: %r" % contents)
            self.fail("contents of %s not as expected" % filename)

    def _getTestDirPrefix(self):
        # create a directory within the top level test directory
        if sys.platform == 'win32':
            name_prefix = re.sub('[<>*=+",:;_/\\-]', '_', self.id())
            # windows is likely to have path-length limits so use a short name
            name_prefix = name_prefix[-30:]
        else:
            name_prefix = re.sub('[/]', '_', self.id())
        return name_prefix

    def makeAndChdirToTestDir(self):
        """See TestCaseWithMemoryTransport.makeAndChdirToTestDir().
        
        For TestCaseInTempDir we create a temporary directory based on the test
        name and then create two subdirs - test and home under it.
        """
        name_prefix = osutils.pathjoin(self.TEST_ROOT, self._getTestDirPrefix())
        name = name_prefix
        for i in range(100):
            if os.path.exists(name):
                name = name_prefix + '_' + str(i)
            else:
                os.mkdir(name)
                break
        # now create test and home directories within this dir
        self.test_base_dir = name
        self.test_home_dir = self.test_base_dir + '/home'
        os.mkdir(self.test_home_dir)
        self.test_dir = self.test_base_dir + '/work'
        os.mkdir(self.test_dir)
        os.chdir(self.test_dir)
        # put name of test inside
        f = file(self.test_base_dir + '/name', 'w')
        try:
            f.write(self.id())
        finally:
            f.close()
        self.addCleanup(self.deleteTestDir)

    def deleteTestDir(self):
        os.chdir(self.TEST_ROOT)
        _rmtree_temp_dir(self.test_base_dir)

    def build_tree(self, shape, line_endings='binary', transport=None):
        """Build a test tree according to a pattern.

        shape is a sequence of file specifications.  If the final
        character is '/', a directory is created.

        This assumes that all the elements in the tree being built are new.

        This doesn't add anything to a branch.

        :type shape:    list or tuple.
        :param line_endings: Either 'binary' or 'native'
            in binary mode, exact contents are written in native mode, the
            line endings match the default platform endings.
        :param transport: A transport to write to, for building trees on VFS's.
            If the transport is readonly or None, "." is opened automatically.
        :return: None
        """
        if type(shape) not in (list, tuple):
            raise AssertionError("Parameter 'shape' should be "
                "a list or a tuple. Got %r instead" % (shape,))
        # It's OK to just create them using forward slashes on windows.
        if transport is None or transport.is_readonly():
            transport = get_transport(".")
        for name in shape:
            self.assertIsInstance(name, basestring)
            if name[-1] == '/':
                transport.mkdir(urlutils.escape(name[:-1]))
            else:
                if line_endings == 'binary':
                    end = '\n'
                elif line_endings == 'native':
                    end = os.linesep
                else:
                    raise errors.BzrError(
                        'Invalid line ending request %r' % line_endings)
                content = "contents of %s%s" % (name.encode('utf-8'), end)
                transport.put_bytes_non_atomic(urlutils.escape(name), content)

    def build_tree_contents(self, shape):
        build_tree_contents(shape)

    def assertInWorkingTree(self, path, root_path='.', tree=None):
        """Assert whether path or paths are in the WorkingTree"""
        if tree is None:
            tree = workingtree.WorkingTree.open(root_path)
        if not isinstance(path, basestring):
            for p in path:
                self.assertInWorkingTree(p, tree=tree)
        else:
            self.assertIsNot(tree.path2id(path), None,
                path+' not in working tree.')

    def assertNotInWorkingTree(self, path, root_path='.', tree=None):
        """Assert whether path or paths are not in the WorkingTree"""
        if tree is None:
            tree = workingtree.WorkingTree.open(root_path)
        if not isinstance(path, basestring):
            for p in path:
                self.assertNotInWorkingTree(p,tree=tree)
        else:
            self.assertIs(tree.path2id(path), None, path+' in working tree.')


class TestCaseWithTransport(TestCaseInTempDir):
    """A test case that provides get_url and get_readonly_url facilities.

    These back onto two transport servers, one for readonly access and one for
    read write access.

    If no explicit class is provided for readonly access, a
    ReadonlyTransportDecorator is used instead which allows the use of non disk
    based read write transports.

    If an explicit class is provided for readonly access, that server and the 
    readwrite one must both define get_url() as resolving to os.getcwd().
    """

    def get_vfs_only_server(self):
        """See TestCaseWithMemoryTransport.

        This is useful for some tests with specific servers that need
        diagnostics.
        """
        if self.__vfs_server is None:
            self.__vfs_server = self.vfs_transport_factory()
            self.__vfs_server.setUp()
            self.addCleanup(self.__vfs_server.tearDown)
        return self.__vfs_server

    def make_branch_and_tree(self, relpath, format=None):
        """Create a branch on the transport and a tree locally.

        If the transport is not a LocalTransport, the Tree can't be created on
        the transport.  In that case if the vfs_transport_factory is
        LocalURLServer the working tree is created in the local
        directory backing the transport, and the returned tree's branch and
        repository will also be accessed locally. Otherwise a lightweight
        checkout is created and returned.

        :param format: The BzrDirFormat.
        :returns: the WorkingTree.
        """
        # TODO: always use the local disk path for the working tree,
        # this obviously requires a format that supports branch references
        # so check for that by checking bzrdir.BzrDirFormat.get_default_format()
        # RBC 20060208
        b = self.make_branch(relpath, format=format)
        try:
            return b.bzrdir.create_workingtree()
        except errors.NotLocalUrl:
            # We can only make working trees locally at the moment.  If the
            # transport can't support them, then we keep the non-disk-backed
            # branch and create a local checkout.
            if self.vfs_transport_factory is LocalURLServer:
                # the branch is colocated on disk, we cannot create a checkout.
                # hopefully callers will expect this.
                local_controldir= bzrdir.BzrDir.open(self.get_vfs_only_url(relpath))
                wt = local_controldir.create_workingtree()
                if wt.branch._format != b._format:
                    wt._branch = b
                    # Make sure that assigning to wt._branch fixes wt.branch,
                    # in case the implementation details of workingtree objects
                    # change.
                    self.assertIs(b, wt.branch)
                return wt
            else:
                return b.create_checkout(relpath, lightweight=True)

    def assertIsDirectory(self, relpath, transport):
        """Assert that relpath within transport is a directory.

        This may not be possible on all transports; in that case it propagates
        a TransportNotPossible.
        """
        try:
            mode = transport.stat(relpath).st_mode
        except errors.NoSuchFile:
            self.fail("path %s is not a directory; no such file"
                      % (relpath))
        if not stat.S_ISDIR(mode):
            self.fail("path %s is not a directory; has mode %#o"
                      % (relpath, mode))

    def assertTreesEqual(self, left, right):
        """Check that left and right have the same content and properties."""
        # we use a tree delta to check for equality of the content, and we
        # manually check for equality of other things such as the parents list.
        self.assertEqual(left.get_parent_ids(), right.get_parent_ids())
        differences = left.changes_from(right)
        self.assertFalse(differences.has_changed(),
            "Trees %r and %r are different: %r" % (left, right, differences))

    def setUp(self):
        super(TestCaseWithTransport, self).setUp()
        self.__vfs_server = None


class ChrootedTestCase(TestCaseWithTransport):
    """A support class that provides readonly urls outside the local namespace.

    This is done by checking if self.transport_server is a MemoryServer. if it
    is then we are chrooted already, if it is not then an HttpServer is used
    for readonly urls.

    TODO RBC 20060127: make this an option to TestCaseWithTransport so it can
                       be used without needed to redo it when a different 
                       subclass is in use ?
    """

    def setUp(self):
        super(ChrootedTestCase, self).setUp()
        if not self.vfs_transport_factory == MemoryServer:
            self.transport_readonly_server = HttpServer


def condition_id_re(pattern):
    """Create a condition filter which performs a re check on a test's id.
    
    :param pattern: A regular expression string.
    :return: A callable that returns True if the re matches.
    """
    filter_re = re.compile(pattern)
    def condition(test):
        test_id = test.id()
        return filter_re.search(test_id)
    return condition


def condition_isinstance(klass_or_klass_list):
    """Create a condition filter which returns isinstance(param, klass).
    
    :return: A callable which when called with one parameter obj return the
        result of isinstance(obj, klass_or_klass_list).
    """
    def condition(obj):
        return isinstance(obj, klass_or_klass_list)
    return condition


def condition_id_in_list(id_list):
    """Create a condition filter which verify that test's id in a list.
    
    :param id_list: A TestIdList object.
    :return: A callable that returns True if the test's id appears in the list.
    """
    def condition(test):
        return id_list.includes(test.id())
    return condition


def condition_id_startswith(starts):
    """Create a condition filter verifying that test's id starts with a string.
    
    :param starts: A list of string.
    :return: A callable that returns True if the test's id starts with one of 
        the given strings.
    """
    def condition(test):
        for start in starts:
            if test.id().startswith(start):
                return True
        return False
    return condition


def exclude_tests_by_condition(suite, condition):
    """Create a test suite which excludes some tests from suite.

    :param suite: The suite to get tests from.
    :param condition: A callable whose result evaluates True when called with a
        test case which should be excluded from the result.
    :return: A suite which contains the tests found in suite that fail
        condition.
    """
    result = []
    for test in iter_suite_tests(suite):
        if not condition(test):
            result.append(test)
    return TestUtil.TestSuite(result)


def filter_suite_by_condition(suite, condition):
    """Create a test suite by filtering another one.
    
    :param suite: The source suite.
    :param condition: A callable whose result evaluates True when called with a
        test case which should be included in the result.
    :return: A suite which contains the tests found in suite that pass
        condition.
    """
    result = []
    for test in iter_suite_tests(suite):
        if condition(test):
            result.append(test)
    return TestUtil.TestSuite(result)


def filter_suite_by_re(suite, pattern):
    """Create a test suite by filtering another one.
    
    :param suite:           the source suite
    :param pattern:         pattern that names must match
    :returns: the newly created suite
    """
    condition = condition_id_re(pattern)
    result_suite = filter_suite_by_condition(suite, condition)
    return result_suite


def filter_suite_by_id_list(suite, test_id_list):
    """Create a test suite by filtering another one.

    :param suite: The source suite.
    :param test_id_list: A list of the test ids to keep as strings.
    :returns: the newly created suite
    """
    condition = condition_id_in_list(test_id_list)
    result_suite = filter_suite_by_condition(suite, condition)
    return result_suite


def filter_suite_by_id_startswith(suite, start):
    """Create a test suite by filtering another one.

    :param suite: The source suite.
    :param start: A list of string the test id must start with one of.
    :returns: the newly created suite
    """
    condition = condition_id_startswith(start)
    result_suite = filter_suite_by_condition(suite, condition)
    return result_suite


def exclude_tests_by_re(suite, pattern):
    """Create a test suite which excludes some tests from suite.

    :param suite: The suite to get tests from.
    :param pattern: A regular expression string. Test ids that match this
        pattern will be excluded from the result.
    :return: A TestSuite that contains all the tests from suite without the
        tests that matched pattern. The order of tests is the same as it was in
        suite.
    """
    return exclude_tests_by_condition(suite, condition_id_re(pattern))


def preserve_input(something):
    """A helper for performing test suite transformation chains.

    :param something: Anything you want to preserve.
    :return: Something.
    """
    return something


def randomize_suite(suite):
    """Return a new TestSuite with suite's tests in random order.
    
    The tests in the input suite are flattened into a single suite in order to
    accomplish this. Any nested TestSuites are removed to provide global
    randomness.
    """
    tests = list(iter_suite_tests(suite))
    random.shuffle(tests)
    return TestUtil.TestSuite(tests)


def split_suite_by_condition(suite, condition):
    """Split a test suite into two by a condition.
    
    :param suite: The suite to split.
    :param condition: The condition to match on. Tests that match this
        condition are returned in the first test suite, ones that do not match
        are in the second suite.
    :return: A tuple of two test suites, where the first contains tests from
        suite matching the condition, and the second contains the remainder
        from suite. The order within each output suite is the same as it was in
        suite.
    """
    matched = []
    did_not_match = []
    for test in iter_suite_tests(suite):
        if condition(test):
            matched.append(test)
        else:
            did_not_match.append(test)
    return TestUtil.TestSuite(matched), TestUtil.TestSuite(did_not_match)


def split_suite_by_re(suite, pattern):
    """Split a test suite into two by a regular expression.
    
    :param suite: The suite to split.
    :param pattern: A regular expression string. Test ids that match this
        pattern will be in the first test suite returned, and the others in the
        second test suite returned.
    :return: A tuple of two test suites, where the first contains tests from
        suite matching pattern, and the second contains the remainder from
        suite. The order within each output suite is the same as it was in
        suite.
    """
    return split_suite_by_condition(suite, condition_id_re(pattern))


def run_suite(suite, name='test', verbose=False, pattern=".*",
              stop_on_failure=False,
              transport=None, lsprof_timed=None, bench_history=None,
              matching_tests_first=None,
              list_only=False,
              random_seed=None,
              exclude_pattern=None,
              strict=False):
    TestCase._gather_lsprof_in_benchmarks = lsprof_timed
    if verbose:
        verbosity = 2
    else:
        verbosity = 1
    runner = TextTestRunner(stream=sys.stdout,
                            descriptions=0,
                            verbosity=verbosity,
                            bench_history=bench_history,
                            list_only=list_only,
                            )
    runner.stop_on_failure=stop_on_failure
    # Initialise the random number generator and display the seed used.
    # We convert the seed to a long to make it reuseable across invocations.
    random_order = False
    if random_seed is not None:
        random_order = True
        if random_seed == "now":
            random_seed = long(time.time())
        else:
            # Convert the seed to a long if we can
            try:
                random_seed = long(random_seed)
            except:
                pass
        runner.stream.writeln("Randomizing test order using seed %s\n" %
            (random_seed))
        random.seed(random_seed)
    # Customise the list of tests if requested
    if exclude_pattern is not None:
        suite = exclude_tests_by_re(suite, exclude_pattern)
    if random_order:
        order_changer = randomize_suite
    else:
        order_changer = preserve_input
    if pattern != '.*' or random_order:
        if matching_tests_first:
            suites = map(order_changer, split_suite_by_re(suite, pattern))
            suite = TestUtil.TestSuite(suites)
        else:
            suite = order_changer(filter_suite_by_re(suite, pattern))

    result = runner.run(suite)

    if strict:
        return result.wasStrictlySuccessful()

    return result.wasSuccessful()


# Controlled by "bzr selftest -E=..." option
selftest_debug_flags = set()


def selftest(verbose=False, pattern=".*", stop_on_failure=True,
             transport=None,
             test_suite_factory=None,
             lsprof_timed=None,
             bench_history=None,
             matching_tests_first=None,
             list_only=False,
             random_seed=None,
             exclude_pattern=None,
             strict=False,
             load_list=None,
             debug_flags=None,
             starting_with=None,
             ):
    """Run the whole test suite under the enhanced runner"""
    # XXX: Very ugly way to do this...
    # Disable warning about old formats because we don't want it to disturb
    # any blackbox tests.
    from bzrlib import repository
    repository._deprecation_warning_done = True

    global default_transport
    if transport is None:
        transport = default_transport
    old_transport = default_transport
    default_transport = transport
    global selftest_debug_flags
    old_debug_flags = selftest_debug_flags
    if debug_flags is not None:
        selftest_debug_flags = set(debug_flags)
    try:
        if load_list is None:
            keep_only = None
        else:
            keep_only = load_test_id_list(load_list)
        if test_suite_factory is None:
            suite = test_suite(keep_only, starting_with)
        else:
            suite = test_suite_factory()
        return run_suite(suite, 'testbzr', verbose=verbose, pattern=pattern,
                     stop_on_failure=stop_on_failure,
                     transport=transport,
                     lsprof_timed=lsprof_timed,
                     bench_history=bench_history,
                     matching_tests_first=matching_tests_first,
                     list_only=list_only,
                     random_seed=random_seed,
                     exclude_pattern=exclude_pattern,
                     strict=strict)
    finally:
        default_transport = old_transport
        selftest_debug_flags = old_debug_flags


def load_test_id_list(file_name):
    """Load a test id list from a text file.

    The format is one test id by line.  No special care is taken to impose
    strict rules, these test ids are used to filter the test suite so a test id
    that do not match an existing test will do no harm. This allows user to add
    comments, leave blank lines, etc.
    """
    test_list = []
    try:
        ftest = open(file_name, 'rt')
    except IOError, e:
        if e.errno != errno.ENOENT:
            raise
        else:
            raise errors.NoSuchFile(file_name)

    for test_name in ftest.readlines():
        test_list.append(test_name.strip())
    ftest.close()
    return test_list


def suite_matches_id_list(test_suite, id_list):
    """Warns about tests not appearing or appearing more than once.

    :param test_suite: A TestSuite object.
    :param test_id_list: The list of test ids that should be found in 
         test_suite.

    :return: (absents, duplicates) absents is a list containing the test found
        in id_list but not in test_suite, duplicates is a list containing the
        test found multiple times in test_suite.

    When using a prefined test id list, it may occurs that some tests do not
    exist anymore or that some tests use the same id. This function warns the
    tester about potential problems in his workflow (test lists are volatile)
    or in the test suite itself (using the same id for several tests does not
    help to localize defects).
    """
    # Build a dict counting id occurrences
    tests = dict()
    for test in iter_suite_tests(test_suite):
        id = test.id()
        tests[id] = tests.get(id, 0) + 1

    not_found = []
    duplicates = []
    for id in id_list:
        occurs = tests.get(id, 0)
        if not occurs:
            not_found.append(id)
        elif occurs > 1:
            duplicates.append(id)

    return not_found, duplicates


class TestIdList(object):
    """Test id list to filter a test suite.

    Relying on the assumption that test ids are built as:
    <module>[.<class>.<method>][(<param>+)], <module> being in python dotted
    notation, this class offers methods to :
    - avoid building a test suite for modules not refered to in the test list,
    - keep only the tests listed from the module test suite.
    """

    def __init__(self, test_id_list):
        # When a test suite needs to be filtered against us we compare test ids
        # for equality, so a simple dict offers a quick and simple solution.
        self.tests = dict().fromkeys(test_id_list, True)

        # While unittest.TestCase have ids like:
        # <module>.<class>.<method>[(<param+)],
        # doctest.DocTestCase can have ids like:
        # <module>
        # <module>.<class>
        # <module>.<function>
        # <module>.<class>.<method>

        # Since we can't predict a test class from its name only, we settle on
        # a simple constraint: a test id always begins with its module name.

        modules = {}
        for test_id in test_id_list:
            parts = test_id.split('.')
            mod_name = parts.pop(0)
            modules[mod_name] = True
            for part in parts:
                mod_name += '.' + part
                modules[mod_name] = True
        self.modules = modules

    def refers_to(self, module_name):
        """Is there tests for the module or one of its sub modules."""
        return self.modules.has_key(module_name)

    def includes(self, test_id):
        return self.tests.has_key(test_id)


class TestPrefixAliasRegistry(registry.Registry):
    """A registry for test prefix aliases.

    This helps implement shorcuts for the --starting-with selftest
    option. Overriding existing prefixes is not allowed but not fatal (a
    warning will be emitted).
    """

    def register(self, key, obj, help=None, info=None,
                 override_existing=False):
        """See Registry.register.

        Trying to override an existing alias causes a warning to be emitted,
        not a fatal execption.
        """
        try:
            super(TestPrefixAliasRegistry, self).register(
                key, obj, help=help, info=info, override_existing=False)
        except KeyError:
            actual = self.get(key)
            note('Test prefix alias %s is already used for %s, ignoring %s'
                 % (key, actual, obj))

    def resolve_alias(self, id_start):
        """Replace the alias by the prefix in the given string.

        Using an unknown prefix is an error to help catching typos.
        """
        parts = id_start.split('.')
        try:
            parts[0] = self.get(parts[0])
        except KeyError:
            raise errors.BzrCommandError(
                '%s is not a known test prefix alias' % parts[0])
        return '.'.join(parts)


test_prefix_alias_registry = TestPrefixAliasRegistry()
"""Registry of test prefix aliases."""


# This alias allows to detect typos ('bzrlin.') by making all valid test ids
# appear prefixed ('bzrlib.' is "replaced" by 'bzrlib.').
test_prefix_alias_registry.register('bzrlib', 'bzrlib')

# Obvious higest levels prefixes, feel free to add your own via a plugin
test_prefix_alias_registry.register('bd', 'bzrlib.doc')
test_prefix_alias_registry.register('bu', 'bzrlib.utils')
test_prefix_alias_registry.register('bt', 'bzrlib.tests')
test_prefix_alias_registry.register('bb', 'bzrlib.tests.blackbox')
test_prefix_alias_registry.register('bp', 'bzrlib.plugins')


def test_suite(keep_only=None, starting_with=None):
    """Build and return TestSuite for the whole of bzrlib.

    :param keep_only: A list of test ids limiting the suite returned.

    :param starting_with: An id limiting the suite returned to the tests
         starting with it.

    This function can be replaced if you need to change the default test
    suite on a global basis, but it is not encouraged.
    """
    testmod_names = [
                   'bzrlib.doc',
                   'bzrlib.util.tests.test_bencode',
                   'bzrlib.tests.blackbox',
                   'bzrlib.tests.branch_implementations',
                   'bzrlib.tests.bzrdir_implementations',
                   'bzrlib.tests.commands',
                   'bzrlib.tests.inventory_implementations',
                   'bzrlib.tests.interrepository_implementations',
                   'bzrlib.tests.intertree_implementations',
                   'bzrlib.tests.per_lock',
                   'bzrlib.tests.per_repository',
                   'bzrlib.tests.test__dirstate_helpers',
                   'bzrlib.tests.test_ancestry',
                   'bzrlib.tests.test_annotate',
                   'bzrlib.tests.test_api',
                   'bzrlib.tests.test_atomicfile',
                   'bzrlib.tests.test_bad_files',
                   'bzrlib.tests.test_bisect_multi',
                   'bzrlib.tests.test_branch',
                   'bzrlib.tests.test_branchbuilder',
                   'bzrlib.tests.test_btree_index',
                   'bzrlib.tests.test_bugtracker',
                   'bzrlib.tests.test_bundle',
                   'bzrlib.tests.test_bzrdir',
                   'bzrlib.tests.test_cache_utf8',
                   'bzrlib.tests.test_chunk_writer',
                   'bzrlib.tests.test_commands',
                   'bzrlib.tests.test_commit',
                   'bzrlib.tests.test_commit_merge',
                   'bzrlib.tests.test_config',
                   'bzrlib.tests.test_conflicts',
                   'bzrlib.tests.test_counted_lock',
                   'bzrlib.tests.test_decorators',
                   'bzrlib.tests.test_delta',
                   'bzrlib.tests.test_deprecated_graph',
                   'bzrlib.tests.test_diff',
                   'bzrlib.tests.test_dirstate',
                   'bzrlib.tests.test_directory_service',
                   'bzrlib.tests.test_email_message',
                   'bzrlib.tests.test_errors',
                   'bzrlib.tests.test_extract',
                   'bzrlib.tests.test_fetch',
                   'bzrlib.tests.test_ftp_transport',
                   'bzrlib.tests.test_generate_docs',
                   'bzrlib.tests.test_generate_ids',
                   'bzrlib.tests.test_globbing',
                   'bzrlib.tests.test_gpg',
                   'bzrlib.tests.test_graph',
                   'bzrlib.tests.test_hashcache',
                   'bzrlib.tests.test_help',
                   'bzrlib.tests.test_hooks',
                   'bzrlib.tests.test_http',
                   'bzrlib.tests.test_http_implementations',
                   'bzrlib.tests.test_http_response',
                   'bzrlib.tests.test_https_ca_bundle',
                   'bzrlib.tests.test_identitymap',
                   'bzrlib.tests.test_ignores',
                   'bzrlib.tests.test_index',
                   'bzrlib.tests.test_info',
                   'bzrlib.tests.test_inv',
                   'bzrlib.tests.test_knit',
                   'bzrlib.tests.test_lazy_import',
                   'bzrlib.tests.test_lazy_regex',
                   'bzrlib.tests.test_lockdir',
                   'bzrlib.tests.test_lockable_files',
                   'bzrlib.tests.test_log',
                   'bzrlib.tests.test_lsprof',
                   'bzrlib.tests.test_lru_cache',
                   'bzrlib.tests.test_mail_client',
                   'bzrlib.tests.test_memorytree',
                   'bzrlib.tests.test_merge',
                   'bzrlib.tests.test_merge3',
                   'bzrlib.tests.test_merge_core',
                   'bzrlib.tests.test_merge_directive',
                   'bzrlib.tests.test_missing',
                   'bzrlib.tests.test_msgeditor',
                   'bzrlib.tests.test_multiparent',
                   'bzrlib.tests.test_mutabletree',
                   'bzrlib.tests.test_nonascii',
                   'bzrlib.tests.test_options',
                   'bzrlib.tests.test_osutils',
                   'bzrlib.tests.test_osutils_encodings',
                   'bzrlib.tests.test_pack',
                   'bzrlib.tests.test_pack_repository',
                   'bzrlib.tests.test_patch',
                   'bzrlib.tests.test_patches',
                   'bzrlib.tests.test_permissions',
                   'bzrlib.tests.test_plugins',
                   'bzrlib.tests.test_progress',
                   'bzrlib.tests.test_read_bundle',
                   'bzrlib.tests.test_reconfigure',
                   'bzrlib.tests.test_reconcile',
                   'bzrlib.tests.test_registry',
                   'bzrlib.tests.test_remote',
                   'bzrlib.tests.test_repository',
                   'bzrlib.tests.per_repository_reference',
                   'bzrlib.tests.test_revert',
                   'bzrlib.tests.test_revision',
                   'bzrlib.tests.test_revisionspec',
                   'bzrlib.tests.test_revisiontree',
                   'bzrlib.tests.test_rio',
                   'bzrlib.tests.test_rules',
                   'bzrlib.tests.test_sampler',
                   'bzrlib.tests.test_selftest',
                   'bzrlib.tests.test_setup',
                   'bzrlib.tests.test_sftp_transport',
                   'bzrlib.tests.test_smart',
                   'bzrlib.tests.test_smart_add',
                   'bzrlib.tests.test_smart_transport',
                   'bzrlib.tests.test_smtp_connection',
                   'bzrlib.tests.test_source',
                   'bzrlib.tests.test_ssh_transport',
                   'bzrlib.tests.test_status',
                   'bzrlib.tests.test_store',
                   'bzrlib.tests.test_strace',
                   'bzrlib.tests.test_subsume',
                   'bzrlib.tests.test_switch',
                   'bzrlib.tests.test_symbol_versioning',
                   'bzrlib.tests.test_tag',
                   'bzrlib.tests.test_testament',
                   'bzrlib.tests.test_textfile',
                   'bzrlib.tests.test_textmerge',
                   'bzrlib.tests.test_timestamp',
                   'bzrlib.tests.test_trace',
                   'bzrlib.tests.test_transactions',
                   'bzrlib.tests.test_transform',
                   'bzrlib.tests.test_transport',
                   'bzrlib.tests.test_transport_implementations',
                   'bzrlib.tests.test_transport_log',
                   'bzrlib.tests.test_tree',
                   'bzrlib.tests.test_treebuilder',
                   'bzrlib.tests.test_tsort',
                   'bzrlib.tests.test_tuned_gzip',
                   'bzrlib.tests.test_ui',
                   'bzrlib.tests.test_uncommit',
                   'bzrlib.tests.test_upgrade',
                   'bzrlib.tests.test_upgrade_stacked',
                   'bzrlib.tests.test_urlutils',
                   'bzrlib.tests.test_versionedfile',
                   'bzrlib.tests.test_version',
                   'bzrlib.tests.test_version_info',
                   'bzrlib.tests.test__walkdirs_win32',
                   'bzrlib.tests.test_weave',
                   'bzrlib.tests.test_whitebox',
                   'bzrlib.tests.test_win32utils',
                   'bzrlib.tests.test_workingtree',
                   'bzrlib.tests.test_workingtree_4',
                   'bzrlib.tests.test_wsgi',
                   'bzrlib.tests.test_xml',
                   'bzrlib.tests.tree_implementations',
                   'bzrlib.tests.workingtree_implementations',
                   ]

    loader = TestUtil.TestLoader()

    if starting_with:
        starting_with = [test_prefix_alias_registry.resolve_alias(start)
                         for start in starting_with]
        # We take precedence over keep_only because *at loading time* using
        # both options means we will load less tests for the same final result.
        def interesting_module(name):
            for start in starting_with:
                if (
                    # Either the module name starts with the specified string
                    name.startswith(start)
                    # or it may contain tests starting with the specified string
                    or start.startswith(name)
                    ):
                    return True
            return False
        loader = TestUtil.FilteredByModuleTestLoader(interesting_module)

    elif keep_only is not None:
        id_filter = TestIdList(keep_only)
        loader = TestUtil.FilteredByModuleTestLoader(id_filter.refers_to)
        def interesting_module(name):
            return id_filter.refers_to(name)

    else:
        loader = TestUtil.TestLoader()
        def interesting_module(name):
            # No filtering, all modules are interesting
            return True

    suite = loader.suiteClass()

    # modules building their suite with loadTestsFromModuleNames
    suite.addTest(loader.loadTestsFromModuleNames(testmod_names))

    modules_to_doctest = [
        'bzrlib',
        'bzrlib.errors',
        'bzrlib.export',
        'bzrlib.inventory',
        'bzrlib.iterablefile',
        'bzrlib.lockdir',
        'bzrlib.merge3',
        'bzrlib.option',
        'bzrlib.store',
        'bzrlib.symbol_versioning',
        'bzrlib.tests',
        'bzrlib.timestamp',
        'bzrlib.version_info_formats.format_custom',
        ]

    for mod in modules_to_doctest:
        if not interesting_module(mod):
            # No tests to keep here, move along
            continue
        try:
            doc_suite = doctest.DocTestSuite(mod)
        except ValueError, e:
            print '**failed to get doctest for: %s\n%s' % (mod, e)
            raise
        suite.addTest(doc_suite)

    default_encoding = sys.getdefaultencoding()
    for name, plugin in bzrlib.plugin.plugins().items():
        if not interesting_module(plugin.module.__name__):
            continue
        plugin_suite = plugin.test_suite()
        # We used to catch ImportError here and turn it into just a warning,
        # but really if you don't have --no-plugins this should be a failure.
        # mbp 20080213 - see http://bugs.launchpad.net/bugs/189771
        if plugin_suite is None:
            plugin_suite = plugin.load_plugin_tests(loader)
        if plugin_suite is not None:
            suite.addTest(plugin_suite)
        if default_encoding != sys.getdefaultencoding():
            bzrlib.trace.warning(
                'Plugin "%s" tried to reset default encoding to: %s', name,
                sys.getdefaultencoding())
            reload(sys)
            sys.setdefaultencoding(default_encoding)

    if starting_with:
        suite = filter_suite_by_id_startswith(suite, starting_with)

    if keep_only is not None:
        # Now that the referred modules have loaded their tests, keep only the
        # requested ones.
        suite = filter_suite_by_id_list(suite, id_filter)
        # Do some sanity checks on the id_list filtering
        not_found, duplicates = suite_matches_id_list(suite, keep_only)
        if starting_with:
            # The tester has used both keep_only and starting_with, so he is
            # already aware that some tests are excluded from the list, there
            # is no need to tell him which.
            pass
        else:
            # Some tests mentioned in the list are not in the test suite. The
            # list may be out of date, report to the tester.
            for id in not_found:
                bzrlib.trace.warning('"%s" not found in the test suite', id)
        for id in duplicates:
            bzrlib.trace.warning('"%s" is used as an id by several tests', id)

    return suite


def multiply_tests_from_modules(module_name_list, scenario_iter, loader=None):
    """Adapt all tests in some given modules to given scenarios.

    This is the recommended public interface for test parameterization.
    Typically the test_suite() method for a per-implementation test
    suite will call multiply_tests_from_modules and return the 
    result.

    :param module_name_list: List of fully-qualified names of test
        modules.
    :param scenario_iter: Iterable of pairs of (scenario_name, 
        scenario_param_dict).
    :param loader: If provided, will be used instead of a new 
        bzrlib.tests.TestLoader() instance.

    This returns a new TestSuite containing the cross product of
    all the tests in all the modules, each repeated for each scenario.
    Each test is adapted by adding the scenario name at the end 
    of its name, and updating the test object's __dict__ with the
    scenario_param_dict.

    >>> r = multiply_tests_from_modules(
    ...     ['bzrlib.tests.test_sampler'],
    ...     [('one', dict(param=1)), 
    ...      ('two', dict(param=2))])
    >>> tests = list(iter_suite_tests(r))
    >>> len(tests)
    2
    >>> tests[0].id()
    'bzrlib.tests.test_sampler.DemoTest.test_nothing(one)'
    >>> tests[0].param
    1
    >>> tests[1].param
    2
    """
    # XXX: Isn't load_tests() a better way to provide the same functionality
    # without forcing a predefined TestScenarioApplier ? --vila 080215
    if loader is None:
        loader = TestUtil.TestLoader()

    suite = loader.suiteClass()

    adapter = TestScenarioApplier()
    adapter.scenarios = list(scenario_iter)
    adapt_modules(module_name_list, adapter, loader, suite)
    return suite


def multiply_scenarios(scenarios_left, scenarios_right):
    """Multiply two sets of scenarios.

    :returns: the cartesian product of the two sets of scenarios, that is
        a scenario for every possible combination of a left scenario and a
        right scenario.
    """
    return [
        ('%s,%s' % (left_name, right_name),
         dict(left_dict.items() + right_dict.items()))
        for left_name, left_dict in scenarios_left
        for right_name, right_dict in scenarios_right]



def adapt_modules(mods_list, adapter, loader, suite):
    """Adapt the modules in mods_list using adapter and add to suite."""
    tests = loader.loadTestsFromModuleNames(mods_list)
    adapt_tests(tests, adapter, suite)


def adapt_tests(tests_list, adapter, suite):
    """Adapt the tests in tests_list using adapter and add to suite."""
    for test in iter_suite_tests(tests_list):
        suite.addTests(adapter.adapt(test))


def _rmtree_temp_dir(dirname):
    # If LANG=C we probably have created some bogus paths
    # which rmtree(unicode) will fail to delete
    # so make sure we are using rmtree(str) to delete everything
    # except on win32, where rmtree(str) will fail
    # since it doesn't have the property of byte-stream paths
    # (they are either ascii or mbcs)
    if sys.platform == 'win32':
        # make sure we are using the unicode win32 api
        dirname = unicode(dirname)
    else:
        dirname = dirname.encode(sys.getfilesystemencoding())
    try:
        osutils.rmtree(dirname)
    except OSError, e:
        if sys.platform == 'win32' and e.errno == errno.EACCES:
            sys.stderr.write(('Permission denied: '
                                 'unable to remove testing dir '
                                 '%s\n' % os.path.basename(dirname)))
        else:
            raise


class Feature(object):
    """An operating system Feature."""

    def __init__(self):
        self._available = None

    def available(self):
        """Is the feature available?

        :return: True if the feature is available.
        """
        if self._available is None:
            self._available = self._probe()
        return self._available

    def _probe(self):
        """Implement this method in concrete features.

        :return: True if the feature is available.
        """
        raise NotImplementedError

    def __str__(self):
        if getattr(self, 'feature_name', None):
            return self.feature_name()
        return self.__class__.__name__


class _SymlinkFeature(Feature):

    def _probe(self):
        return osutils.has_symlinks()

    def feature_name(self):
        return 'symlinks'

SymlinkFeature = _SymlinkFeature()


class _HardlinkFeature(Feature):

    def _probe(self):
        return osutils.has_hardlinks()

    def feature_name(self):
        return 'hardlinks'

HardlinkFeature = _HardlinkFeature()


class _OsFifoFeature(Feature):

    def _probe(self):
        return getattr(os, 'mkfifo', None)

    def feature_name(self):
        return 'filesystem fifos'

OsFifoFeature = _OsFifoFeature()


class _UnicodeFilenameFeature(Feature):
    """Does the filesystem support Unicode filenames?"""

    def _probe(self):
        try:
            # Check for character combinations unlikely to be covered by any
            # single non-unicode encoding. We use the characters
            # - greek small letter alpha (U+03B1) and
            # - braille pattern dots-123456 (U+283F).
            os.stat(u'\u03b1\u283f')
        except UnicodeEncodeError:
            return False
        except (IOError, OSError):
            # The filesystem allows the Unicode filename but the file doesn't
            # exist.
            return True
        else:
            # The filesystem allows the Unicode filename and the file exists,
            # for some reason.
            return True

UnicodeFilenameFeature = _UnicodeFilenameFeature()


class TestScenarioApplier(object):
    """A tool to apply scenarios to tests."""

    def adapt(self, test):
        """Return a TestSuite containing a copy of test for each scenario."""
        result = unittest.TestSuite()
        for scenario in self.scenarios:
            result.addTest(self.adapt_test_to_scenario(test, scenario))
        return result

    def adapt_test_to_scenario(self, test, scenario):
        """Copy test and apply scenario to it.

        :param test: A test to adapt.
        :param scenario: A tuple describing the scenarion.
            The first element of the tuple is the new test id.
            The second element is a dict containing attributes to set on the
            test.
        :return: The adapted test.
        """
        from copy import deepcopy
        new_test = deepcopy(test)
        for name, value in scenario[1].items():
            setattr(new_test, name, value)
        new_id = "%s(%s)" % (new_test.id(), scenario[0])
        new_test.id = lambda: new_id
        return new_test


def probe_unicode_in_user_encoding():
    """Try to encode several unicode strings to use in unicode-aware tests.
    Return first successfull match.

    :return:  (unicode value, encoded plain string value) or (None, None)
    """
    possible_vals = [u'm\xb5', u'\xe1', u'\u0410']
    for uni_val in possible_vals:
        try:
            str_val = uni_val.encode(osutils.get_user_encoding())
        except UnicodeEncodeError:
            # Try a different character
            pass
        else:
            return uni_val, str_val
    return None, None


def probe_bad_non_ascii(encoding):
    """Try to find [bad] character with code [128..255]
    that cannot be decoded to unicode in some encoding.
    Return None if all non-ascii characters is valid
    for given encoding.
    """
    for i in xrange(128, 256):
        char = chr(i)
        try:
            char.decode(encoding)
        except UnicodeDecodeError:
            return char
    return None


class _FTPServerFeature(Feature):
    """Some tests want an FTP Server, check if one is available.

    Right now, the only way this is available is if 'medusa' is installed.
    http://www.amk.ca/python/code/medusa.html
    """

    def _probe(self):
        try:
            import bzrlib.tests.ftp_server
            return True
        except ImportError:
            return False

    def feature_name(self):
        return 'FTPServer'

FTPServerFeature = _FTPServerFeature()


class _UnicodeFilename(Feature):
    """Does the filesystem support Unicode filenames?"""

    def _probe(self):
        try:
            os.stat(u'\u03b1')
        except UnicodeEncodeError:
            return False
        except (IOError, OSError):
            # The filesystem allows the Unicode filename but the file doesn't
            # exist.
            return True
        else:
            # The filesystem allows the Unicode filename and the file exists,
            # for some reason.
            return True

UnicodeFilename = _UnicodeFilename()


class _UTF8Filesystem(Feature):
    """Is the filesystem UTF-8?"""

    def _probe(self):
        if osutils._fs_enc.upper() in ('UTF-8', 'UTF8'):
            return True
        return False

UTF8Filesystem = _UTF8Filesystem()


class _CaseInsensitiveFilesystemFeature(Feature):
    """Check if underlying filesystem is case-insensitive
    (e.g. on Windows, Cygwin, MacOS)
    """

    def _probe(self):
        if TestCaseWithMemoryTransport.TEST_ROOT is None:
            root = osutils.mkdtemp(prefix='testbzr-', suffix='.tmp')
            TestCaseWithMemoryTransport.TEST_ROOT = root
        else:
            root = TestCaseWithMemoryTransport.TEST_ROOT
        tdir = osutils.mkdtemp(prefix='case-sensitive-probe-', suffix='',
            dir=root)
        name_a = osutils.pathjoin(tdir, 'a')
        name_A = osutils.pathjoin(tdir, 'A')
        os.mkdir(name_a)
        result = osutils.isdir(name_A)
        _rmtree_temp_dir(tdir)
        return result

    def feature_name(self):
        return 'case-insensitive filesystem'

CaseInsensitiveFilesystemFeature = _CaseInsensitiveFilesystemFeature()