Library import 16 (#2433)

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1 files changed, 1456 insertions, 0 deletions

diff --git a/contrib/tools/python3/Lib/unittest/case.py b/contrib/tools/python3/Lib/unittest/case.py
new file mode 100644
index 0000000000..001b640dc4
--- /dev/null
+++ b/contrib/tools/python3/Lib/unittest/case.py
@@ -0,0 +1,1456 @@
+"""Test case implementation"""
+
+import sys
+import functools
+import difflib
+import pprint
+import re
+import warnings
+import collections
+import contextlib
+import traceback
+import time
+import types
+
+from . import result
+from .util import (strclass, safe_repr, _count_diff_all_purpose,
+                   _count_diff_hashable, _common_shorten_repr)
+
+__unittest = True
+
+_subtest_msg_sentinel = object()
+
+DIFF_OMITTED = ('\nDiff is %s characters long. '
+                 'Set self.maxDiff to None to see it.')
+
+class SkipTest(Exception):
+    """
+    Raise this exception in a test to skip it.
+
+    Usually you can use TestCase.skipTest() or one of the skipping decorators
+    instead of raising this directly.
+    """
+
+class _ShouldStop(Exception):
+    """
+    The test should stop.
+    """
+
+class _UnexpectedSuccess(Exception):
+    """
+    The test was supposed to fail, but it didn't!
+    """
+
+
+class _Outcome(object):
+    def __init__(self, result=None):
+        self.expecting_failure = False
+        self.result = result
+        self.result_supports_subtests = hasattr(result, "addSubTest")
+        self.success = True
+        self.expectedFailure = None
+
+    @contextlib.contextmanager
+    def testPartExecutor(self, test_case, subTest=False):
+        old_success = self.success
+        self.success = True
+        try:
+            yield
+        except KeyboardInterrupt:
+            raise
+        except SkipTest as e:
+            self.success = False
+            _addSkip(self.result, test_case, str(e))
+        except _ShouldStop:
+            pass
+        except:
+            exc_info = sys.exc_info()
+            if self.expecting_failure:
+                self.expectedFailure = exc_info
+            else:
+                self.success = False
+                if subTest:
+                    self.result.addSubTest(test_case.test_case, test_case, exc_info)
+                else:
+                    _addError(self.result, test_case, exc_info)
+            # explicitly break a reference cycle:
+            # exc_info -> frame -> exc_info
+            exc_info = None
+        else:
+            if subTest and self.success:
+                self.result.addSubTest(test_case.test_case, test_case, None)
+        finally:
+            self.success = self.success and old_success
+
+
+def _addSkip(result, test_case, reason):
+    addSkip = getattr(result, 'addSkip', None)
+    if addSkip is not None:
+        addSkip(test_case, reason)
+    else:
+        warnings.warn("TestResult has no addSkip method, skips not reported",
+                      RuntimeWarning, 2)
+        result.addSuccess(test_case)
+
+def _addError(result, test, exc_info):
+    if result is not None and exc_info is not None:
+        if issubclass(exc_info[0], test.failureException):
+            result.addFailure(test, exc_info)
+        else:
+            result.addError(test, exc_info)
+
+def _id(obj):
+    return obj
+
+
+def _enter_context(cm, addcleanup):
+    # We look up the special methods on the type to match the with
+    # statement.
+    cls = type(cm)
+    try:
+        enter = cls.__enter__
+        exit = cls.__exit__
+    except AttributeError:
+        raise TypeError(f"'{cls.__module__}.{cls.__qualname__}' object does "
+                        f"not support the context manager protocol") from None
+    result = enter(cm)
+    addcleanup(exit, cm, None, None, None)
+    return result
+
+
+_module_cleanups = []
+def addModuleCleanup(function, /, *args, **kwargs):
+    """Same as addCleanup, except the cleanup items are called even if
+    setUpModule fails (unlike tearDownModule)."""
+    _module_cleanups.append((function, args, kwargs))
+
+def enterModuleContext(cm):
+    """Same as enterContext, but module-wide."""
+    return _enter_context(cm, addModuleCleanup)
+
+
+def doModuleCleanups():
+    """Execute all module cleanup functions. Normally called for you after
+    tearDownModule."""
+    exceptions = []
+    while _module_cleanups:
+        function, args, kwargs = _module_cleanups.pop()
+        try:
+            function(*args, **kwargs)
+        except Exception as exc:
+            exceptions.append(exc)
+    if exceptions:
+        # Swallows all but first exception. If a multi-exception handler
+        # gets written we should use that here instead.
+        raise exceptions[0]
+
+
+def skip(reason):
+    """
+    Unconditionally skip a test.
+    """
+    def decorator(test_item):
+        if not isinstance(test_item, type):
+            @functools.wraps(test_item)
+            def skip_wrapper(*args, **kwargs):
+                raise SkipTest(reason)
+            test_item = skip_wrapper
+
+        test_item.__unittest_skip__ = True
+        test_item.__unittest_skip_why__ = reason
+        return test_item
+    if isinstance(reason, types.FunctionType):
+        test_item = reason
+        reason = ''
+        return decorator(test_item)
+    return decorator
+
+def skipIf(condition, reason):
+    """
+    Skip a test if the condition is true.
+    """
+    if condition:
+        return skip(reason)
+    return _id
+
+def skipUnless(condition, reason):
+    """
+    Skip a test unless the condition is true.
+    """
+    if not condition:
+        return skip(reason)
+    return _id
+
+def expectedFailure(test_item):
+    test_item.__unittest_expecting_failure__ = True
+    return test_item
+
+def _is_subtype(expected, basetype):
+    if isinstance(expected, tuple):
+        return all(_is_subtype(e, basetype) for e in expected)
+    return isinstance(expected, type) and issubclass(expected, basetype)
+
+class _BaseTestCaseContext:
+
+    def __init__(self, test_case):
+        self.test_case = test_case
+
+    def _raiseFailure(self, standardMsg):
+        msg = self.test_case._formatMessage(self.msg, standardMsg)
+        raise self.test_case.failureException(msg)
+
+class _AssertRaisesBaseContext(_BaseTestCaseContext):
+
+    def __init__(self, expected, test_case, expected_regex=None):
+        _BaseTestCaseContext.__init__(self, test_case)
+        self.expected = expected
+        self.test_case = test_case
+        if expected_regex is not None:
+            expected_regex = re.compile(expected_regex)
+        self.expected_regex = expected_regex
+        self.obj_name = None
+        self.msg = None
+
+    def handle(self, name, args, kwargs):
+        """
+        If args is empty, assertRaises/Warns is being used as a
+        context manager, so check for a 'msg' kwarg and return self.
+        If args is not empty, call a callable passing positional and keyword
+        arguments.
+        """
+        try:
+            if not _is_subtype(self.expected, self._base_type):
+                raise TypeError('%s() arg 1 must be %s' %
+                                (name, self._base_type_str))
+            if not args:
+                self.msg = kwargs.pop('msg', None)
+                if kwargs:
+                    raise TypeError('%r is an invalid keyword argument for '
+                                    'this function' % (next(iter(kwargs)),))
+                return self
+
+            callable_obj, *args = args
+            try:
+                self.obj_name = callable_obj.__name__
+            except AttributeError:
+                self.obj_name = str(callable_obj)
+            with self:
+                callable_obj(*args, **kwargs)
+        finally:
+            # bpo-23890: manually break a reference cycle
+            self = None
+
+
+class _AssertRaisesContext(_AssertRaisesBaseContext):
+    """A context manager used to implement TestCase.assertRaises* methods."""
+
+    _base_type = BaseException
+    _base_type_str = 'an exception type or tuple of exception types'
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        if exc_type is None:
+            try:
+                exc_name = self.expected.__name__
+            except AttributeError:
+                exc_name = str(self.expected)
+            if self.obj_name:
+                self._raiseFailure("{} not raised by {}".format(exc_name,
+                                                                self.obj_name))
+            else:
+                self._raiseFailure("{} not raised".format(exc_name))
+        else:
+            traceback.clear_frames(tb)
+        if not issubclass(exc_type, self.expected):
+            # let unexpected exceptions pass through
+            return False
+        # store exception, without traceback, for later retrieval
+        self.exception = exc_value.with_traceback(None)
+        if self.expected_regex is None:
+            return True
+
+        expected_regex = self.expected_regex
+        if not expected_regex.search(str(exc_value)):
+            self._raiseFailure('"{}" does not match "{}"'.format(
+                     expected_regex.pattern, str(exc_value)))
+        return True
+
+    __class_getitem__ = classmethod(types.GenericAlias)
+
+
+class _AssertWarnsContext(_AssertRaisesBaseContext):
+    """A context manager used to implement TestCase.assertWarns* methods."""
+
+    _base_type = Warning
+    _base_type_str = 'a warning type or tuple of warning types'
+
+    def __enter__(self):
+        # The __warningregistry__'s need to be in a pristine state for tests
+        # to work properly.
+        for v in list(sys.modules.values()):
+            if getattr(v, '__warningregistry__', None):
+                v.__warningregistry__ = {}
+        self.warnings_manager = warnings.catch_warnings(record=True)
+        self.warnings = self.warnings_manager.__enter__()
+        warnings.simplefilter("always", self.expected)
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        self.warnings_manager.__exit__(exc_type, exc_value, tb)
+        if exc_type is not None:
+            # let unexpected exceptions pass through
+            return
+        try:
+            exc_name = self.expected.__name__
+        except AttributeError:
+            exc_name = str(self.expected)
+        first_matching = None
+        for m in self.warnings:
+            w = m.message
+            if not isinstance(w, self.expected):
+                continue
+            if first_matching is None:
+                first_matching = w
+            if (self.expected_regex is not None and
+                not self.expected_regex.search(str(w))):
+                continue
+            # store warning for later retrieval
+            self.warning = w
+            self.filename = m.filename
+            self.lineno = m.lineno
+            return
+        # Now we simply try to choose a helpful failure message
+        if first_matching is not None:
+            self._raiseFailure('"{}" does not match "{}"'.format(
+                     self.expected_regex.pattern, str(first_matching)))
+        if self.obj_name:
+            self._raiseFailure("{} not triggered by {}".format(exc_name,
+                                                               self.obj_name))
+        else:
+            self._raiseFailure("{} not triggered".format(exc_name))
+
+
+class _OrderedChainMap(collections.ChainMap):
+    def __iter__(self):
+        seen = set()
+        for mapping in self.maps:
+            for k in mapping:
+                if k not in seen:
+                    seen.add(k)
+                    yield k
+
+
+class TestCase(object):
+    """A class whose instances are single test cases.
+
+    By default, the test code itself should be placed in a method named
+    'runTest'.
+
+    If the fixture may be used for many test cases, create as
+    many test methods as are needed. When instantiating such a TestCase
+    subclass, specify in the constructor arguments the name of the test method
+    that the instance is to execute.
+
+    Test authors should subclass TestCase for their own tests. Construction
+    and deconstruction of the test's environment ('fixture') can be
+    implemented by overriding the 'setUp' and 'tearDown' methods respectively.
+
+    If it is necessary to override the __init__ method, the base class
+    __init__ method must always be called. It is important that subclasses
+    should not change the signature of their __init__ method, since instances
+    of the classes are instantiated automatically by parts of the framework
+    in order to be run.
+
+    When subclassing TestCase, you can set these attributes:
+    * failureException: determines which exception will be raised when
+        the instance's assertion methods fail; test methods raising this
+        exception will be deemed to have 'failed' rather than 'errored'.
+    * longMessage: determines whether long messages (including repr of
+        objects used in assert methods) will be printed on failure in *addition*
+        to any explicit message passed.
+    * maxDiff: sets the maximum length of a diff in failure messages
+        by assert methods using difflib. It is looked up as an instance
+        attribute so can be configured by individual tests if required.
+    """
+
+    failureException = AssertionError
+
+    longMessage = True
+
+    maxDiff = 80*8
+
+    # If a string is longer than _diffThreshold, use normal comparison instead
+    # of difflib.  See #11763.
+    _diffThreshold = 2**16
+
+    def __init_subclass__(cls, *args, **kwargs):
+        # Attribute used by TestSuite for classSetUp
+        cls._classSetupFailed = False
+        cls._class_cleanups = []
+        super().__init_subclass__(*args, **kwargs)
+
+    def __init__(self, methodName='runTest'):
+        """Create an instance of the class that will use the named test
+           method when executed. Raises a ValueError if the instance does
+           not have a method with the specified name.
+        """
+        self._testMethodName = methodName
+        self._outcome = None
+        self._testMethodDoc = 'No test'
+        try:
+            testMethod = getattr(self, methodName)
+        except AttributeError:
+            if methodName != 'runTest':
+                # we allow instantiation with no explicit method name
+                # but not an *incorrect* or missing method name
+                raise ValueError("no such test method in %s: %s" %
+                      (self.__class__, methodName))
+        else:
+            self._testMethodDoc = testMethod.__doc__
+        self._cleanups = []
+        self._subtest = None
+
+        # Map types to custom assertEqual functions that will compare
+        # instances of said type in more detail to generate a more useful
+        # error message.
+        self._type_equality_funcs = {}
+        self.addTypeEqualityFunc(dict, 'assertDictEqual')
+        self.addTypeEqualityFunc(list, 'assertListEqual')
+        self.addTypeEqualityFunc(tuple, 'assertTupleEqual')
+        self.addTypeEqualityFunc(set, 'assertSetEqual')
+        self.addTypeEqualityFunc(frozenset, 'assertSetEqual')
+        self.addTypeEqualityFunc(str, 'assertMultiLineEqual')
+
+    def addTypeEqualityFunc(self, typeobj, function):
+        """Add a type specific assertEqual style function to compare a type.
+
+        This method is for use by TestCase subclasses that need to register
+        their own type equality functions to provide nicer error messages.
+
+        Args:
+            typeobj: The data type to call this function on when both values
+                    are of the same type in assertEqual().
+            function: The callable taking two arguments and an optional
+                    msg= argument that raises self.failureException with a
+                    useful error message when the two arguments are not equal.
+        """
+        self._type_equality_funcs[typeobj] = function
+
+    def addCleanup(self, function, /, *args, **kwargs):
+        """Add a function, with arguments, to be called when the test is
+        completed. Functions added are called on a LIFO basis and are
+        called after tearDown on test failure or success.
+
+        Cleanup items are called even if setUp fails (unlike tearDown)."""
+        self._cleanups.append((function, args, kwargs))
+
+    def enterContext(self, cm):
+        """Enters the supplied context manager.
+
+        If successful, also adds its __exit__ method as a cleanup
+        function and returns the result of the __enter__ method.
+        """
+        return _enter_context(cm, self.addCleanup)
+
+    @classmethod
+    def addClassCleanup(cls, function, /, *args, **kwargs):
+        """Same as addCleanup, except the cleanup items are called even if
+        setUpClass fails (unlike tearDownClass)."""
+        cls._class_cleanups.append((function, args, kwargs))
+
+    @classmethod
+    def enterClassContext(cls, cm):
+        """Same as enterContext, but class-wide."""
+        return _enter_context(cm, cls.addClassCleanup)
+
+    def setUp(self):
+        "Hook method for setting up the test fixture before exercising it."
+        pass
+
+    def tearDown(self):
+        "Hook method for deconstructing the test fixture after testing it."
+        pass
+
+    @classmethod
+    def setUpClass(cls):
+        "Hook method for setting up class fixture before running tests in the class."
+
+    @classmethod
+    def tearDownClass(cls):
+        "Hook method for deconstructing the class fixture after running all tests in the class."
+
+    def countTestCases(self):
+        return 1
+
+    def defaultTestResult(self):
+        return result.TestResult()
+
+    def shortDescription(self):
+        """Returns a one-line description of the test, or None if no
+        description has been provided.
+
+        The default implementation of this method returns the first line of
+        the specified test method's docstring.
+        """
+        doc = self._testMethodDoc
+        return doc.strip().split("\n")[0].strip() if doc else None
+
+
+    def id(self):
+        return "%s.%s" % (strclass(self.__class__), self._testMethodName)
+
+    def __eq__(self, other):
+        if type(self) is not type(other):
+            return NotImplemented
+
+        return self._testMethodName == other._testMethodName
+
+    def __hash__(self):
+        return hash((type(self), self._testMethodName))
+
+    def __str__(self):
+        return "%s (%s.%s)" % (self._testMethodName, strclass(self.__class__), self._testMethodName)
+
+    def __repr__(self):
+        return "<%s testMethod=%s>" % \
+               (strclass(self.__class__), self._testMethodName)
+
+    @contextlib.contextmanager
+    def subTest(self, msg=_subtest_msg_sentinel, **params):
+        """Return a context manager that will return the enclosed block
+        of code in a subtest identified by the optional message and
+        keyword parameters.  A failure in the subtest marks the test
+        case as failed but resumes execution at the end of the enclosed
+        block, allowing further test code to be executed.
+        """
+        if self._outcome is None or not self._outcome.result_supports_subtests:
+            yield
+            return
+        parent = self._subtest
+        if parent is None:
+            params_map = _OrderedChainMap(params)
+        else:
+            params_map = parent.params.new_child(params)
+        self._subtest = _SubTest(self, msg, params_map)
+        try:
+            with self._outcome.testPartExecutor(self._subtest, subTest=True):
+                yield
+            if not self._outcome.success:
+                result = self._outcome.result
+                if result is not None and result.failfast:
+                    raise _ShouldStop
+            elif self._outcome.expectedFailure:
+                # If the test is expecting a failure, we really want to
+                # stop now and register the expected failure.
+                raise _ShouldStop
+        finally:
+            self._subtest = parent
+
+    def _addExpectedFailure(self, result, exc_info):
+        try:
+            addExpectedFailure = result.addExpectedFailure
+        except AttributeError:
+            warnings.warn("TestResult has no addExpectedFailure method, reporting as passes",
+                          RuntimeWarning)
+            result.addSuccess(self)
+        else:
+            addExpectedFailure(self, exc_info)
+
+    def _addUnexpectedSuccess(self, result):
+        try:
+            addUnexpectedSuccess = result.addUnexpectedSuccess
+        except AttributeError:
+            warnings.warn("TestResult has no addUnexpectedSuccess method, reporting as failure",
+                          RuntimeWarning)
+            # We need to pass an actual exception and traceback to addFailure,
+            # otherwise the legacy result can choke.
+            try:
+                raise _UnexpectedSuccess from None
+            except _UnexpectedSuccess:
+                result.addFailure(self, sys.exc_info())
+        else:
+            addUnexpectedSuccess(self)
+
+    def _addDuration(self, result, elapsed):
+        try:
+            addDuration = result.addDuration
+        except AttributeError:
+            warnings.warn("TestResult has no addDuration method",
+                          RuntimeWarning)
+        else:
+            addDuration(self, elapsed)
+
+    def _callSetUp(self):
+        self.setUp()
+
+    def _callTestMethod(self, method):
+        if method() is not None:
+            warnings.warn(f'It is deprecated to return a value that is not None from a '
+                          f'test case ({method})', DeprecationWarning, stacklevel=3)
+
+    def _callTearDown(self):
+        self.tearDown()
+
+    def _callCleanup(self, function, /, *args, **kwargs):
+        function(*args, **kwargs)
+
+    def run(self, result=None):
+        if result is None:
+            result = self.defaultTestResult()
+            startTestRun = getattr(result, 'startTestRun', None)
+            stopTestRun = getattr(result, 'stopTestRun', None)
+            if startTestRun is not None:
+                startTestRun()
+        else:
+            stopTestRun = None
+
+        result.startTest(self)
+        try:
+            testMethod = getattr(self, self._testMethodName)
+            if (getattr(self.__class__, "__unittest_skip__", False) or
+                getattr(testMethod, "__unittest_skip__", False)):
+                # If the class or method was skipped.
+                skip_why = (getattr(self.__class__, '__unittest_skip_why__', '')
+                            or getattr(testMethod, '__unittest_skip_why__', ''))
+                _addSkip(result, self, skip_why)
+                return result
+
+            expecting_failure = (
+                getattr(self, "__unittest_expecting_failure__", False) or
+                getattr(testMethod, "__unittest_expecting_failure__", False)
+            )
+            outcome = _Outcome(result)
+            start_time = time.perf_counter()
+            try:
+                self._outcome = outcome
+
+                with outcome.testPartExecutor(self):
+                    self._callSetUp()
+                if outcome.success:
+                    outcome.expecting_failure = expecting_failure
+                    with outcome.testPartExecutor(self):
+                        self._callTestMethod(testMethod)
+                    outcome.expecting_failure = False
+                    with outcome.testPartExecutor(self):
+                        self._callTearDown()
+                self.doCleanups()
+                self._addDuration(result, (time.perf_counter() - start_time))
+
+                if outcome.success:
+                    if expecting_failure:
+                        if outcome.expectedFailure:
+                            self._addExpectedFailure(result, outcome.expectedFailure)
+                        else:
+                            self._addUnexpectedSuccess(result)
+                    else:
+                        result.addSuccess(self)
+                return result
+            finally:
+                # explicitly break reference cycle:
+                # outcome.expectedFailure -> frame -> outcome -> outcome.expectedFailure
+                outcome.expectedFailure = None
+                outcome = None
+
+                # clear the outcome, no more needed
+                self._outcome = None
+
+        finally:
+            result.stopTest(self)
+            if stopTestRun is not None:
+                stopTestRun()
+
+    def doCleanups(self):
+        """Execute all cleanup functions. Normally called for you after
+        tearDown."""
+        outcome = self._outcome or _Outcome()
+        while self._cleanups:
+            function, args, kwargs = self._cleanups.pop()
+            with outcome.testPartExecutor(self):
+                self._callCleanup(function, *args, **kwargs)
+
+        # return this for backwards compatibility
+        # even though we no longer use it internally
+        return outcome.success
+
+    @classmethod
+    def doClassCleanups(cls):
+        """Execute all class cleanup functions. Normally called for you after
+        tearDownClass."""
+        cls.tearDown_exceptions = []
+        while cls._class_cleanups:
+            function, args, kwargs = cls._class_cleanups.pop()
+            try:
+                function(*args, **kwargs)
+            except Exception:
+                cls.tearDown_exceptions.append(sys.exc_info())
+
+    def __call__(self, *args, **kwds):
+        return self.run(*args, **kwds)
+
+    def debug(self):
+        """Run the test without collecting errors in a TestResult"""
+        testMethod = getattr(self, self._testMethodName)
+        if (getattr(self.__class__, "__unittest_skip__", False) or
+            getattr(testMethod, "__unittest_skip__", False)):
+            # If the class or method was skipped.
+            skip_why = (getattr(self.__class__, '__unittest_skip_why__', '')
+                        or getattr(testMethod, '__unittest_skip_why__', ''))
+            raise SkipTest(skip_why)
+
+        self._callSetUp()
+        self._callTestMethod(testMethod)
+        self._callTearDown()
+        while self._cleanups:
+            function, args, kwargs = self._cleanups.pop()
+            self._callCleanup(function, *args, **kwargs)
+
+    def skipTest(self, reason):
+        """Skip this test."""
+        raise SkipTest(reason)
+
+    def fail(self, msg=None):
+        """Fail immediately, with the given message."""
+        raise self.failureException(msg)
+
+    def assertFalse(self, expr, msg=None):
+        """Check that the expression is false."""
+        if expr:
+            msg = self._formatMessage(msg, "%s is not false" % safe_repr(expr))
+            raise self.failureException(msg)
+
+    def assertTrue(self, expr, msg=None):
+        """Check that the expression is true."""
+        if not expr:
+            msg = self._formatMessage(msg, "%s is not true" % safe_repr(expr))
+            raise self.failureException(msg)
+
+    def _formatMessage(self, msg, standardMsg):
+        """Honour the longMessage attribute when generating failure messages.
+        If longMessage is False this means:
+        * Use only an explicit message if it is provided
+        * Otherwise use the standard message for the assert
+
+        If longMessage is True:
+        * Use the standard message
+        * If an explicit message is provided, plus ' : ' and the explicit message
+        """
+        if not self.longMessage:
+            return msg or standardMsg
+        if msg is None:
+            return standardMsg
+        try:
+            # don't switch to '{}' formatting in Python 2.X
+            # it changes the way unicode input is handled
+            return '%s : %s' % (standardMsg, msg)
+        except UnicodeDecodeError:
+            return  '%s : %s' % (safe_repr(standardMsg), safe_repr(msg))
+
+    def assertRaises(self, expected_exception, *args, **kwargs):
+        """Fail unless an exception of class expected_exception is raised
+           by the callable when invoked with specified positional and
+           keyword arguments. If a different type of exception is
+           raised, it will not be caught, and the test case will be
+           deemed to have suffered an error, exactly as for an
+           unexpected exception.
+
+           If called with the callable and arguments omitted, will return a
+           context object used like this::
+
+                with self.assertRaises(SomeException):
+                    do_something()
+
+           An optional keyword argument 'msg' can be provided when assertRaises
+           is used as a context object.
+
+           The context manager keeps a reference to the exception as
+           the 'exception' attribute. This allows you to inspect the
+           exception after the assertion::
+
+               with self.assertRaises(SomeException) as cm:
+                   do_something()
+               the_exception = cm.exception
+               self.assertEqual(the_exception.error_code, 3)
+        """
+        context = _AssertRaisesContext(expected_exception, self)
+        try:
+            return context.handle('assertRaises', args, kwargs)
+        finally:
+            # bpo-23890: manually break a reference cycle
+            context = None
+
+    def assertWarns(self, expected_warning, *args, **kwargs):
+        """Fail unless a warning of class warnClass is triggered
+           by the callable when invoked with specified positional and
+           keyword arguments.  If a different type of warning is
+           triggered, it will not be handled: depending on the other
+           warning filtering rules in effect, it might be silenced, printed
+           out, or raised as an exception.
+
+           If called with the callable and arguments omitted, will return a
+           context object used like this::
+
+                with self.assertWarns(SomeWarning):
+                    do_something()
+
+           An optional keyword argument 'msg' can be provided when assertWarns
+           is used as a context object.
+
+           The context manager keeps a reference to the first matching
+           warning as the 'warning' attribute; similarly, the 'filename'
+           and 'lineno' attributes give you information about the line
+           of Python code from which the warning was triggered.
+           This allows you to inspect the warning after the assertion::
+
+               with self.assertWarns(SomeWarning) as cm:
+                   do_something()
+               the_warning = cm.warning
+               self.assertEqual(the_warning.some_attribute, 147)
+        """
+        context = _AssertWarnsContext(expected_warning, self)
+        return context.handle('assertWarns', args, kwargs)
+
+    def assertLogs(self, logger=None, level=None):
+        """Fail unless a log message of level *level* or higher is emitted
+        on *logger_name* or its children.  If omitted, *level* defaults to
+        INFO and *logger* defaults to the root logger.
+
+        This method must be used as a context manager, and will yield
+        a recording object with two attributes: `output` and `records`.
+        At the end of the context manager, the `output` attribute will
+        be a list of the matching formatted log messages and the
+        `records` attribute will be a list of the corresponding LogRecord
+        objects.
+
+        Example::
+
+            with self.assertLogs('foo', level='INFO') as cm:
+                logging.getLogger('foo').info('first message')
+                logging.getLogger('foo.bar').error('second message')
+            self.assertEqual(cm.output, ['INFO:foo:first message',
+                                         'ERROR:foo.bar:second message'])
+        """
+        # Lazy import to avoid importing logging if it is not needed.
+        from ._log import _AssertLogsContext
+        return _AssertLogsContext(self, logger, level, no_logs=False)
+
+    def assertNoLogs(self, logger=None, level=None):
+        """ Fail unless no log messages of level *level* or higher are emitted
+        on *logger_name* or its children.
+
+        This method must be used as a context manager.
+        """
+        from ._log import _AssertLogsContext
+        return _AssertLogsContext(self, logger, level, no_logs=True)
+
+    def _getAssertEqualityFunc(self, first, second):
+        """Get a detailed comparison function for the types of the two args.
+
+        Returns: A callable accepting (first, second, msg=None) that will
+        raise a failure exception if first != second with a useful human
+        readable error message for those types.
+        """
+        #
+        # NOTE(gregory.p.smith): I considered isinstance(first, type(second))
+        # and vice versa.  I opted for the conservative approach in case
+        # subclasses are not intended to be compared in detail to their super
+        # class instances using a type equality func.  This means testing
+        # subtypes won't automagically use the detailed comparison.  Callers
+        # should use their type specific assertSpamEqual method to compare
+        # subclasses if the detailed comparison is desired and appropriate.
+        # See the discussion in http://bugs.python.org/issue2578.
+        #
+        if type(first) is type(second):
+            asserter = self._type_equality_funcs.get(type(first))
+            if asserter is not None:
+                if isinstance(asserter, str):
+                    asserter = getattr(self, asserter)
+                return asserter
+
+        return self._baseAssertEqual
+
+    def _baseAssertEqual(self, first, second, msg=None):
+        """The default assertEqual implementation, not type specific."""
+        if not first == second:
+            standardMsg = '%s != %s' % _common_shorten_repr(first, second)
+            msg = self._formatMessage(msg, standardMsg)
+            raise self.failureException(msg)
+
+    def assertEqual(self, first, second, msg=None):
+        """Fail if the two objects are unequal as determined by the '=='
+           operator.
+        """
+        assertion_func = self._getAssertEqualityFunc(first, second)
+        assertion_func(first, second, msg=msg)
+
+    def assertNotEqual(self, first, second, msg=None):
+        """Fail if the two objects are equal as determined by the '!='
+           operator.
+        """
+        if not first != second:
+            msg = self._formatMessage(msg, '%s == %s' % (safe_repr(first),
+                                                          safe_repr(second)))
+            raise self.failureException(msg)
+
+    def assertAlmostEqual(self, first, second, places=None, msg=None,
+                          delta=None):
+        """Fail if the two objects are unequal as determined by their
+           difference rounded to the given number of decimal places
+           (default 7) and comparing to zero, or by comparing that the
+           difference between the two objects is more than the given
+           delta.
+
+           Note that decimal places (from zero) are usually not the same
+           as significant digits (measured from the most significant digit).
+
+           If the two objects compare equal then they will automatically
+           compare almost equal.
+        """
+        if first == second:
+            # shortcut
+            return
+        if delta is not None and places is not None:
+            raise TypeError("specify delta or places not both")
+
+        diff = abs(first - second)
+        if delta is not None:
+            if diff <= delta:
+                return
+
+            standardMsg = '%s != %s within %s delta (%s difference)' % (
+                safe_repr(first),
+                safe_repr(second),
+                safe_repr(delta),
+                safe_repr(diff))
+        else:
+            if places is None:
+                places = 7
+
+            if round(diff, places) == 0:
+                return
+
+            standardMsg = '%s != %s within %r places (%s difference)' % (
+                safe_repr(first),
+                safe_repr(second),
+                places,
+                safe_repr(diff))
+        msg = self._formatMessage(msg, standardMsg)
+        raise self.failureException(msg)
+
+    def assertNotAlmostEqual(self, first, second, places=None, msg=None,
+                             delta=None):
+        """Fail if the two objects are equal as determined by their
+           difference rounded to the given number of decimal places
+           (default 7) and comparing to zero, or by comparing that the
+           difference between the two objects is less than the given delta.
+
+           Note that decimal places (from zero) are usually not the same
+           as significant digits (measured from the most significant digit).
+
+           Objects that are equal automatically fail.
+        """
+        if delta is not None and places is not None:
+            raise TypeError("specify delta or places not both")
+        diff = abs(first - second)
+        if delta is not None:
+            if not (first == second) and diff > delta:
+                return
+            standardMsg = '%s == %s within %s delta (%s difference)' % (
+                safe_repr(first),
+                safe_repr(second),
+                safe_repr(delta),
+                safe_repr(diff))
+        else:
+            if places is None:
+                places = 7
+            if not (first == second) and round(diff, places) != 0:
+                return
+            standardMsg = '%s == %s within %r places' % (safe_repr(first),
+                                                         safe_repr(second),
+                                                         places)
+
+        msg = self._formatMessage(msg, standardMsg)
+        raise self.failureException(msg)
+
+    def assertSequenceEqual(self, seq1, seq2, msg=None, seq_type=None):
+        """An equality assertion for ordered sequences (like lists and tuples).
+
+        For the purposes of this function, a valid ordered sequence type is one
+        which can be indexed, has a length, and has an equality operator.
+
+        Args:
+            seq1: The first sequence to compare.
+            seq2: The second sequence to compare.
+            seq_type: The expected datatype of the sequences, or None if no
+                    datatype should be enforced.
+            msg: Optional message to use on failure instead of a list of
+                    differences.
+        """
+        if seq_type is not None:
+            seq_type_name = seq_type.__name__
+            if not isinstance(seq1, seq_type):
+                raise self.failureException('First sequence is not a %s: %s'
+                                        % (seq_type_name, safe_repr(seq1)))
+            if not isinstance(seq2, seq_type):
+                raise self.failureException('Second sequence is not a %s: %s'
+                                        % (seq_type_name, safe_repr(seq2)))
+        else:
+            seq_type_name = "sequence"
+
+        differing = None
+        try:
+            len1 = len(seq1)
+        except (TypeError, NotImplementedError):
+            differing = 'First %s has no length.    Non-sequence?' % (
+                    seq_type_name)
+
+        if differing is None:
+            try:
+                len2 = len(seq2)
+            except (TypeError, NotImplementedError):
+                differing = 'Second %s has no length.    Non-sequence?' % (
+                        seq_type_name)
+
+        if differing is None:
+            if seq1 == seq2:
+                return
+
+            differing = '%ss differ: %s != %s\n' % (
+                    (seq_type_name.capitalize(),) +
+                    _common_shorten_repr(seq1, seq2))
+
+            for i in range(min(len1, len2)):
+                try:
+                    item1 = seq1[i]
+                except (TypeError, IndexError, NotImplementedError):
+                    differing += ('\nUnable to index element %d of first %s\n' %
+                                 (i, seq_type_name))
+                    break
+
+                try:
+                    item2 = seq2[i]
+                except (TypeError, IndexError, NotImplementedError):
+                    differing += ('\nUnable to index element %d of second %s\n' %
+                                 (i, seq_type_name))
+                    break
+
+                if item1 != item2:
+                    differing += ('\nFirst differing element %d:\n%s\n%s\n' %
+                                 ((i,) + _common_shorten_repr(item1, item2)))
+                    break
+            else:
+                if (len1 == len2 and seq_type is None and
+                    type(seq1) != type(seq2)):
+                    # The sequences are the same, but have differing types.
+                    return
+
+            if len1 > len2:
+                differing += ('\nFirst %s contains %d additional '
+                             'elements.\n' % (seq_type_name, len1 - len2))
+                try:
+                    differing += ('First extra element %d:\n%s\n' %
+                                  (len2, safe_repr(seq1[len2])))
+                except (TypeError, IndexError, NotImplementedError):
+                    differing += ('Unable to index element %d '
+                                  'of first %s\n' % (len2, seq_type_name))
+            elif len1 < len2:
+                differing += ('\nSecond %s contains %d additional '
+                             'elements.\n' % (seq_type_name, len2 - len1))
+                try:
+                    differing += ('First extra element %d:\n%s\n' %
+                                  (len1, safe_repr(seq2[len1])))
+                except (TypeError, IndexError, NotImplementedError):
+                    differing += ('Unable to index element %d '
+                                  'of second %s\n' % (len1, seq_type_name))
+        standardMsg = differing
+        diffMsg = '\n' + '\n'.join(
+            difflib.ndiff(pprint.pformat(seq1).splitlines(),
+                          pprint.pformat(seq2).splitlines()))
+
+        standardMsg = self._truncateMessage(standardMsg, diffMsg)
+        msg = self._formatMessage(msg, standardMsg)
+        self.fail(msg)
+
+    def _truncateMessage(self, message, diff):
+        max_diff = self.maxDiff
+        if max_diff is None or len(diff) <= max_diff:
+            return message + diff
+        return message + (DIFF_OMITTED % len(diff))
+
+    def assertListEqual(self, list1, list2, msg=None):
+        """A list-specific equality assertion.
+
+        Args:
+            list1: The first list to compare.
+            list2: The second list to compare.
+            msg: Optional message to use on failure instead of a list of
+                    differences.
+
+        """
+        self.assertSequenceEqual(list1, list2, msg, seq_type=list)
+
+    def assertTupleEqual(self, tuple1, tuple2, msg=None):
+        """A tuple-specific equality assertion.
+
+        Args:
+            tuple1: The first tuple to compare.
+            tuple2: The second tuple to compare.
+            msg: Optional message to use on failure instead of a list of
+                    differences.
+        """
+        self.assertSequenceEqual(tuple1, tuple2, msg, seq_type=tuple)
+
+    def assertSetEqual(self, set1, set2, msg=None):
+        """A set-specific equality assertion.
+
+        Args:
+            set1: The first set to compare.
+            set2: The second set to compare.
+            msg: Optional message to use on failure instead of a list of
+                    differences.
+
+        assertSetEqual uses ducktyping to support different types of sets, and
+        is optimized for sets specifically (parameters must support a
+        difference method).
+        """
+        try:
+            difference1 = set1.difference(set2)
+        except TypeError as e:
+            self.fail('invalid type when attempting set difference: %s' % e)
+        except AttributeError as e:
+            self.fail('first argument does not support set difference: %s' % e)
+
+        try:
+            difference2 = set2.difference(set1)
+        except TypeError as e:
+            self.fail('invalid type when attempting set difference: %s' % e)
+        except AttributeError as e:
+            self.fail('second argument does not support set difference: %s' % e)
+
+        if not (difference1 or difference2):
+            return
+
+        lines = []
+        if difference1:
+            lines.append('Items in the first set but not the second:')
+            for item in difference1:
+                lines.append(repr(item))
+        if difference2:
+            lines.append('Items in the second set but not the first:')
+            for item in difference2:
+                lines.append(repr(item))
+
+        standardMsg = '\n'.join(lines)
+        self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertIn(self, member, container, msg=None):
+        """Just like self.assertTrue(a in b), but with a nicer default message."""
+        if member not in container:
+            standardMsg = '%s not found in %s' % (safe_repr(member),
+                                                  safe_repr(container))
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertNotIn(self, member, container, msg=None):
+        """Just like self.assertTrue(a not in b), but with a nicer default message."""
+        if member in container:
+            standardMsg = '%s unexpectedly found in %s' % (safe_repr(member),
+                                                        safe_repr(container))
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertIs(self, expr1, expr2, msg=None):
+        """Just like self.assertTrue(a is b), but with a nicer default message."""
+        if expr1 is not expr2:
+            standardMsg = '%s is not %s' % (safe_repr(expr1),
+                                             safe_repr(expr2))
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertIsNot(self, expr1, expr2, msg=None):
+        """Just like self.assertTrue(a is not b), but with a nicer default message."""
+        if expr1 is expr2:
+            standardMsg = 'unexpectedly identical: %s' % (safe_repr(expr1),)
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertDictEqual(self, d1, d2, msg=None):
+        self.assertIsInstance(d1, dict, 'First argument is not a dictionary')
+        self.assertIsInstance(d2, dict, 'Second argument is not a dictionary')
+
+        if d1 != d2:
+            standardMsg = '%s != %s' % _common_shorten_repr(d1, d2)
+            diff = ('\n' + '\n'.join(difflib.ndiff(
+                           pprint.pformat(d1).splitlines(),
+                           pprint.pformat(d2).splitlines())))
+            standardMsg = self._truncateMessage(standardMsg, diff)
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertCountEqual(self, first, second, msg=None):
+        """Asserts that two iterables have the same elements, the same number of
+        times, without regard to order.
+
+            self.assertEqual(Counter(list(first)),
+                             Counter(list(second)))
+
+         Example:
+            - [0, 1, 1] and [1, 0, 1] compare equal.
+            - [0, 0, 1] and [0, 1] compare unequal.
+
+        """
+        first_seq, second_seq = list(first), list(second)
+        try:
+            first = collections.Counter(first_seq)
+            second = collections.Counter(second_seq)
+        except TypeError:
+            # Handle case with unhashable elements
+            differences = _count_diff_all_purpose(first_seq, second_seq)
+        else:
+            if first == second:
+                return
+            differences = _count_diff_hashable(first_seq, second_seq)
+
+        if differences:
+            standardMsg = 'Element counts were not equal:\n'
+            lines = ['First has %d, Second has %d:  %r' % diff for diff in differences]
+            diffMsg = '\n'.join(lines)
+            standardMsg = self._truncateMessage(standardMsg, diffMsg)
+            msg = self._formatMessage(msg, standardMsg)
+            self.fail(msg)
+
+    def assertMultiLineEqual(self, first, second, msg=None):
+        """Assert that two multi-line strings are equal."""
+        self.assertIsInstance(first, str, "First argument is not a string")
+        self.assertIsInstance(second, str, "Second argument is not a string")
+
+        if first != second:
+            # Don't use difflib if the strings are too long
+            if (len(first) > self._diffThreshold or
+                len(second) > self._diffThreshold):
+                self._baseAssertEqual(first, second, msg)
+
+            # Append \n to both strings if either is missing the \n.
+            # This allows the final ndiff to show the \n difference. The
+            # exception here is if the string is empty, in which case no
+            # \n should be added
+            first_presplit = first
+            second_presplit = second
+            if first and second:
+                if first[-1] != '\n' or second[-1] != '\n':
+                    first_presplit += '\n'
+                    second_presplit += '\n'
+            elif second and second[-1] != '\n':
+                second_presplit += '\n'
+            elif first and first[-1] != '\n':
+                first_presplit += '\n'
+
+            firstlines = first_presplit.splitlines(keepends=True)
+            secondlines = second_presplit.splitlines(keepends=True)
+
+            # Generate the message and diff, then raise the exception
+            standardMsg = '%s != %s' % _common_shorten_repr(first, second)
+            diff = '\n' + ''.join(difflib.ndiff(firstlines, secondlines))
+            standardMsg = self._truncateMessage(standardMsg, diff)
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertLess(self, a, b, msg=None):
+        """Just like self.assertTrue(a < b), but with a nicer default message."""
+        if not a < b:
+            standardMsg = '%s not less than %s' % (safe_repr(a), safe_repr(b))
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertLessEqual(self, a, b, msg=None):
+        """Just like self.assertTrue(a <= b), but with a nicer default message."""
+        if not a <= b:
+            standardMsg = '%s not less than or equal to %s' % (safe_repr(a), safe_repr(b))
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertGreater(self, a, b, msg=None):
+        """Just like self.assertTrue(a > b), but with a nicer default message."""
+        if not a > b:
+            standardMsg = '%s not greater than %s' % (safe_repr(a), safe_repr(b))
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertGreaterEqual(self, a, b, msg=None):
+        """Just like self.assertTrue(a >= b), but with a nicer default message."""
+        if not a >= b:
+            standardMsg = '%s not greater than or equal to %s' % (safe_repr(a), safe_repr(b))
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertIsNone(self, obj, msg=None):
+        """Same as self.assertTrue(obj is None), with a nicer default message."""
+        if obj is not None:
+            standardMsg = '%s is not None' % (safe_repr(obj),)
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertIsNotNone(self, obj, msg=None):
+        """Included for symmetry with assertIsNone."""
+        if obj is None:
+            standardMsg = 'unexpectedly None'
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertIsInstance(self, obj, cls, msg=None):
+        """Same as self.assertTrue(isinstance(obj, cls)), with a nicer
+        default message."""
+        if not isinstance(obj, cls):
+            standardMsg = '%s is not an instance of %r' % (safe_repr(obj), cls)
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertNotIsInstance(self, obj, cls, msg=None):
+        """Included for symmetry with assertIsInstance."""
+        if isinstance(obj, cls):
+            standardMsg = '%s is an instance of %r' % (safe_repr(obj), cls)
+            self.fail(self._formatMessage(msg, standardMsg))
+
+    def assertRaisesRegex(self, expected_exception, expected_regex,
+                          *args, **kwargs):
+        """Asserts that the message in a raised exception matches a regex.
+
+        Args:
+            expected_exception: Exception class expected to be raised.
+            expected_regex: Regex (re.Pattern object or string) expected
+                    to be found in error message.
+            args: Function to be called and extra positional args.
+            kwargs: Extra kwargs.
+            msg: Optional message used in case of failure. Can only be used
+                    when assertRaisesRegex is used as a context manager.
+        """
+        context = _AssertRaisesContext(expected_exception, self, expected_regex)
+        return context.handle('assertRaisesRegex', args, kwargs)
+
+    def assertWarnsRegex(self, expected_warning, expected_regex,
+                         *args, **kwargs):
+        """Asserts that the message in a triggered warning matches a regexp.
+        Basic functioning is similar to assertWarns() with the addition
+        that only warnings whose messages also match the regular expression
+        are considered successful matches.
+
+        Args:
+            expected_warning: Warning class expected to be triggered.
+            expected_regex: Regex (re.Pattern object or string) expected
+                    to be found in error message.
+            args: Function to be called and extra positional args.
+            kwargs: Extra kwargs.
+            msg: Optional message used in case of failure. Can only be used
+                    when assertWarnsRegex is used as a context manager.
+        """
+        context = _AssertWarnsContext(expected_warning, self, expected_regex)
+        return context.handle('assertWarnsRegex', args, kwargs)
+
+    def assertRegex(self, text, expected_regex, msg=None):
+        """Fail the test unless the text matches the regular expression."""
+        if isinstance(expected_regex, (str, bytes)):
+            assert expected_regex, "expected_regex must not be empty."
+            expected_regex = re.compile(expected_regex)
+        if not expected_regex.search(text):
+            standardMsg = "Regex didn't match: %r not found in %r" % (
+                expected_regex.pattern, text)
+            # _formatMessage ensures the longMessage option is respected
+            msg = self._formatMessage(msg, standardMsg)
+            raise self.failureException(msg)
+
+    def assertNotRegex(self, text, unexpected_regex, msg=None):
+        """Fail the test if the text matches the regular expression."""
+        if isinstance(unexpected_regex, (str, bytes)):
+            unexpected_regex = re.compile(unexpected_regex)
+        match = unexpected_regex.search(text)
+        if match:
+            standardMsg = 'Regex matched: %r matches %r in %r' % (
+                text[match.start() : match.end()],
+                unexpected_regex.pattern,
+                text)
+            # _formatMessage ensures the longMessage option is respected
+            msg = self._formatMessage(msg, standardMsg)
+            raise self.failureException(msg)
+
+
+
+class FunctionTestCase(TestCase):
+    """A test case that wraps a test function.
+
+    This is useful for slipping pre-existing test functions into the
+    unittest framework. Optionally, set-up and tidy-up functions can be
+    supplied. As with TestCase, the tidy-up ('tearDown') function will
+    always be called if the set-up ('setUp') function ran successfully.
+    """
+
+    def __init__(self, testFunc, setUp=None, tearDown=None, description=None):
+        super(FunctionTestCase, self).__init__()
+        self._setUpFunc = setUp
+        self._tearDownFunc = tearDown
+        self._testFunc = testFunc
+        self._description = description
+
+    def setUp(self):
+        if self._setUpFunc is not None:
+            self._setUpFunc()
+
+    def tearDown(self):
+        if self._tearDownFunc is not None:
+            self._tearDownFunc()
+
+    def runTest(self):
+        self._testFunc()
+
+    def id(self):
+        return self._testFunc.__name__
+
+    def __eq__(self, other):
+        if not isinstance(other, self.__class__):
+            return NotImplemented
+
+        return self._setUpFunc == other._setUpFunc and \
+               self._tearDownFunc == other._tearDownFunc and \
+               self._testFunc == other._testFunc and \
+               self._description == other._description
+
+    def __hash__(self):
+        return hash((type(self), self._setUpFunc, self._tearDownFunc,
+                     self._testFunc, self._description))
+
+    def __str__(self):
+        return "%s (%s)" % (strclass(self.__class__),
+                            self._testFunc.__name__)
+
+    def __repr__(self):
+        return "<%s tec=%s>" % (strclass(self.__class__),
+                                     self._testFunc)
+
+    def shortDescription(self):
+        if self._description is not None:
+            return self._description
+        doc = self._testFunc.__doc__
+        return doc and doc.split("\n")[0].strip() or None
+
+
+class _SubTest(TestCase):
+
+    def __init__(self, test_case, message, params):
+        super().__init__()
+        self._message = message
+        self.test_case = test_case
+        self.params = params
+        self.failureException = test_case.failureException
+
+    def runTest(self):
+        raise NotImplementedError("subtests cannot be run directly")
+
+    def _subDescription(self):
+        parts = []
+        if self._message is not _subtest_msg_sentinel:
+            parts.append("[{}]".format(self._message))
+        if self.params:
+            params_desc = ', '.join(
+                "{}={!r}".format(k, v)
+                for (k, v) in self.params.items())
+            parts.append("({})".format(params_desc))
+        return " ".join(parts) or '(<subtest>)'
+
+    def id(self):
+        return "{} {}".format(self.test_case.id(), self._subDescription())
+
+    def shortDescription(self):
+        """Returns a one-line description of the subtest, or None if no
+        description has been provided.
+        """
+        return self.test_case.shortDescription()
+
+    def __str__(self):
+        return "{} {}".format(self.test_case, self._subDescription())