python-3.6.zip added from Github

README.cosmo contains the necessary links.

third_party/python/Lib/test/test_with.py

@@ -0,0 +1,746 @@
+"""Unit tests for the with statement specified in PEP 343."""
+
+
+__author__ = "Mike Bland"
+__email__ = "mbland at acm dot org"
+
+import sys
+import unittest
+from collections import deque
+from contextlib import _GeneratorContextManager, contextmanager
+
+
+class MockContextManager(_GeneratorContextManager):
+    def __init__(self, *args):
+        super().__init__(*args)
+        self.enter_called = False
+        self.exit_called = False
+        self.exit_args = None
+
+    def __enter__(self):
+        self.enter_called = True
+        return _GeneratorContextManager.__enter__(self)
+
+    def __exit__(self, type, value, traceback):
+        self.exit_called = True
+        self.exit_args = (type, value, traceback)
+        return _GeneratorContextManager.__exit__(self, type,
+                                                 value, traceback)
+
+
+def mock_contextmanager(func):
+    def helper(*args, **kwds):
+        return MockContextManager(func, args, kwds)
+    return helper
+
+
+class MockResource(object):
+    def __init__(self):
+        self.yielded = False
+        self.stopped = False
+
+
+@mock_contextmanager
+def mock_contextmanager_generator():
+    mock = MockResource()
+    try:
+        mock.yielded = True
+        yield mock
+    finally:
+        mock.stopped = True
+
+
+class Nested(object):
+
+    def __init__(self, *managers):
+        self.managers = managers
+        self.entered = None
+
+    def __enter__(self):
+        if self.entered is not None:
+            raise RuntimeError("Context is not reentrant")
+        self.entered = deque()
+        vars = []
+        try:
+            for mgr in self.managers:
+                vars.append(mgr.__enter__())
+                self.entered.appendleft(mgr)
+        except:
+            if not self.__exit__(*sys.exc_info()):
+                raise
+        return vars
+
+    def __exit__(self, *exc_info):
+        # Behave like nested with statements
+        # first in, last out
+        # New exceptions override old ones
+        ex = exc_info
+        for mgr in self.entered:
+            try:
+                if mgr.__exit__(*ex):
+                    ex = (None, None, None)
+            except:
+                ex = sys.exc_info()
+        self.entered = None
+        if ex is not exc_info:
+            raise ex[0](ex[1]).with_traceback(ex[2])
+
+
+class MockNested(Nested):
+    def __init__(self, *managers):
+        Nested.__init__(self, *managers)
+        self.enter_called = False
+        self.exit_called = False
+        self.exit_args = None
+
+    def __enter__(self):
+        self.enter_called = True
+        return Nested.__enter__(self)
+
+    def __exit__(self, *exc_info):
+        self.exit_called = True
+        self.exit_args = exc_info
+        return Nested.__exit__(self, *exc_info)
+
+
+class FailureTestCase(unittest.TestCase):
+    def testNameError(self):
+        def fooNotDeclared():
+            with foo: pass
+        self.assertRaises(NameError, fooNotDeclared)
+
+    def testEnterAttributeError1(self):
+        class LacksEnter(object):
+            def __exit__(self, type, value, traceback):
+                pass
+
+        def fooLacksEnter():
+            foo = LacksEnter()
+            with foo: pass
+        self.assertRaisesRegex(AttributeError, '__enter__', fooLacksEnter)
+
+    def testEnterAttributeError2(self):
+        class LacksEnterAndExit(object):
+            pass
+
+        def fooLacksEnterAndExit():
+            foo = LacksEnterAndExit()
+            with foo: pass
+        self.assertRaisesRegex(AttributeError, '__enter__', fooLacksEnterAndExit)
+
+    def testExitAttributeError(self):
+        class LacksExit(object):
+            def __enter__(self):
+                pass
+
+        def fooLacksExit():
+            foo = LacksExit()
+            with foo: pass
+        self.assertRaisesRegex(AttributeError, '__exit__', fooLacksExit)
+
+    def assertRaisesSyntaxError(self, codestr):
+        def shouldRaiseSyntaxError(s):
+            compile(s, '', 'single')
+        self.assertRaises(SyntaxError, shouldRaiseSyntaxError, codestr)
+
+    def testAssignmentToNoneError(self):
+        self.assertRaisesSyntaxError('with mock as None:\n  pass')
+        self.assertRaisesSyntaxError(
+            'with mock as (None):\n'
+            '  pass')
+
+    def testAssignmentToTupleOnlyContainingNoneError(self):
+        self.assertRaisesSyntaxError('with mock as None,:\n  pass')
+        self.assertRaisesSyntaxError(
+            'with mock as (None,):\n'
+            '  pass')
+
+    def testAssignmentToTupleContainingNoneError(self):
+        self.assertRaisesSyntaxError(
+            'with mock as (foo, None, bar):\n'
+            '  pass')
+
+    def testEnterThrows(self):
+        class EnterThrows(object):
+            def __enter__(self):
+                raise RuntimeError("Enter threw")
+            def __exit__(self, *args):
+                pass
+
+        def shouldThrow():
+            ct = EnterThrows()
+            self.foo = None
+            with ct as self.foo:
+                pass
+        self.assertRaises(RuntimeError, shouldThrow)
+        self.assertEqual(self.foo, None)
+
+    def testExitThrows(self):
+        class ExitThrows(object):
+            def __enter__(self):
+                return
+            def __exit__(self, *args):
+                raise RuntimeError(42)
+        def shouldThrow():
+            with ExitThrows():
+                pass
+        self.assertRaises(RuntimeError, shouldThrow)
+
+class ContextmanagerAssertionMixin(object):
+
+    def setUp(self):
+        self.TEST_EXCEPTION = RuntimeError("test exception")
+
+    def assertInWithManagerInvariants(self, mock_manager):
+        self.assertTrue(mock_manager.enter_called)
+        self.assertFalse(mock_manager.exit_called)
+        self.assertEqual(mock_manager.exit_args, None)
+
+    def assertAfterWithManagerInvariants(self, mock_manager, exit_args):
+        self.assertTrue(mock_manager.enter_called)
+        self.assertTrue(mock_manager.exit_called)
+        self.assertEqual(mock_manager.exit_args, exit_args)
+
+    def assertAfterWithManagerInvariantsNoError(self, mock_manager):
+        self.assertAfterWithManagerInvariants(mock_manager,
+            (None, None, None))
+
+    def assertInWithGeneratorInvariants(self, mock_generator):
+        self.assertTrue(mock_generator.yielded)
+        self.assertFalse(mock_generator.stopped)
+
+    def assertAfterWithGeneratorInvariantsNoError(self, mock_generator):
+        self.assertTrue(mock_generator.yielded)
+        self.assertTrue(mock_generator.stopped)
+
+    def raiseTestException(self):
+        raise self.TEST_EXCEPTION
+
+    def assertAfterWithManagerInvariantsWithError(self, mock_manager,
+                                                  exc_type=None):
+        self.assertTrue(mock_manager.enter_called)
+        self.assertTrue(mock_manager.exit_called)
+        if exc_type is None:
+            self.assertEqual(mock_manager.exit_args[1], self.TEST_EXCEPTION)
+            exc_type = type(self.TEST_EXCEPTION)
+        self.assertEqual(mock_manager.exit_args[0], exc_type)
+        # Test the __exit__ arguments. Issue #7853
+        self.assertIsInstance(mock_manager.exit_args[1], exc_type)
+        self.assertIsNot(mock_manager.exit_args[2], None)
+
+    def assertAfterWithGeneratorInvariantsWithError(self, mock_generator):
+        self.assertTrue(mock_generator.yielded)
+        self.assertTrue(mock_generator.stopped)
+
+
+class NonexceptionalTestCase(unittest.TestCase, ContextmanagerAssertionMixin):
+    def testInlineGeneratorSyntax(self):
+        with mock_contextmanager_generator():
+            pass
+
+    def testUnboundGenerator(self):
+        mock = mock_contextmanager_generator()
+        with mock:
+            pass
+        self.assertAfterWithManagerInvariantsNoError(mock)
+
+    def testInlineGeneratorBoundSyntax(self):
+        with mock_contextmanager_generator() as foo:
+            self.assertInWithGeneratorInvariants(foo)
+        # FIXME: In the future, we'll try to keep the bound names from leaking
+        self.assertAfterWithGeneratorInvariantsNoError(foo)
+
+    def testInlineGeneratorBoundToExistingVariable(self):
+        foo = None
+        with mock_contextmanager_generator() as foo:
+            self.assertInWithGeneratorInvariants(foo)
+        self.assertAfterWithGeneratorInvariantsNoError(foo)
+
+    def testInlineGeneratorBoundToDottedVariable(self):
+        with mock_contextmanager_generator() as self.foo:
+            self.assertInWithGeneratorInvariants(self.foo)
+        self.assertAfterWithGeneratorInvariantsNoError(self.foo)
+
+    def testBoundGenerator(self):
+        mock = mock_contextmanager_generator()
+        with mock as foo:
+            self.assertInWithGeneratorInvariants(foo)
+            self.assertInWithManagerInvariants(mock)
+        self.assertAfterWithGeneratorInvariantsNoError(foo)
+        self.assertAfterWithManagerInvariantsNoError(mock)
+
+    def testNestedSingleStatements(self):
+        mock_a = mock_contextmanager_generator()
+        with mock_a as foo:
+            mock_b = mock_contextmanager_generator()
+            with mock_b as bar:
+                self.assertInWithManagerInvariants(mock_a)
+                self.assertInWithManagerInvariants(mock_b)
+                self.assertInWithGeneratorInvariants(foo)
+                self.assertInWithGeneratorInvariants(bar)
+            self.assertAfterWithManagerInvariantsNoError(mock_b)
+            self.assertAfterWithGeneratorInvariantsNoError(bar)
+            self.assertInWithManagerInvariants(mock_a)
+            self.assertInWithGeneratorInvariants(foo)
+        self.assertAfterWithManagerInvariantsNoError(mock_a)
+        self.assertAfterWithGeneratorInvariantsNoError(foo)
+
+
+class NestedNonexceptionalTestCase(unittest.TestCase,
+    ContextmanagerAssertionMixin):
+    def testSingleArgInlineGeneratorSyntax(self):
+        with Nested(mock_contextmanager_generator()):
+            pass
+
+    def testSingleArgBoundToNonTuple(self):
+        m = mock_contextmanager_generator()
+        # This will bind all the arguments to nested() into a single list
+        # assigned to foo.
+        with Nested(m) as foo:
+            self.assertInWithManagerInvariants(m)
+        self.assertAfterWithManagerInvariantsNoError(m)
+
+    def testSingleArgBoundToSingleElementParenthesizedList(self):
+        m = mock_contextmanager_generator()
+        # This will bind all the arguments to nested() into a single list
+        # assigned to foo.
+        with Nested(m) as (foo):
+            self.assertInWithManagerInvariants(m)
+        self.assertAfterWithManagerInvariantsNoError(m)
+
+    def testSingleArgBoundToMultipleElementTupleError(self):
+        def shouldThrowValueError():
+            with Nested(mock_contextmanager_generator()) as (foo, bar):
+                pass
+        self.assertRaises(ValueError, shouldThrowValueError)
+
+    def testSingleArgUnbound(self):
+        mock_contextmanager = mock_contextmanager_generator()
+        mock_nested = MockNested(mock_contextmanager)
+        with mock_nested:
+            self.assertInWithManagerInvariants(mock_contextmanager)
+            self.assertInWithManagerInvariants(mock_nested)
+        self.assertAfterWithManagerInvariantsNoError(mock_contextmanager)
+        self.assertAfterWithManagerInvariantsNoError(mock_nested)
+
+    def testMultipleArgUnbound(self):
+        m = mock_contextmanager_generator()
+        n = mock_contextmanager_generator()
+        o = mock_contextmanager_generator()
+        mock_nested = MockNested(m, n, o)
+        with mock_nested:
+            self.assertInWithManagerInvariants(m)
+            self.assertInWithManagerInvariants(n)
+            self.assertInWithManagerInvariants(o)
+            self.assertInWithManagerInvariants(mock_nested)
+        self.assertAfterWithManagerInvariantsNoError(m)
+        self.assertAfterWithManagerInvariantsNoError(n)
+        self.assertAfterWithManagerInvariantsNoError(o)
+        self.assertAfterWithManagerInvariantsNoError(mock_nested)
+
+    def testMultipleArgBound(self):
+        mock_nested = MockNested(mock_contextmanager_generator(),
+            mock_contextmanager_generator(), mock_contextmanager_generator())
+        with mock_nested as (m, n, o):
+            self.assertInWithGeneratorInvariants(m)
+            self.assertInWithGeneratorInvariants(n)
+            self.assertInWithGeneratorInvariants(o)
+            self.assertInWithManagerInvariants(mock_nested)
+        self.assertAfterWithGeneratorInvariantsNoError(m)
+        self.assertAfterWithGeneratorInvariantsNoError(n)
+        self.assertAfterWithGeneratorInvariantsNoError(o)
+        self.assertAfterWithManagerInvariantsNoError(mock_nested)
+
+
+class ExceptionalTestCase(ContextmanagerAssertionMixin, unittest.TestCase):
+    def testSingleResource(self):
+        cm = mock_contextmanager_generator()
+        def shouldThrow():
+            with cm as self.resource:
+                self.assertInWithManagerInvariants(cm)
+                self.assertInWithGeneratorInvariants(self.resource)
+                self.raiseTestException()
+        self.assertRaises(RuntimeError, shouldThrow)
+        self.assertAfterWithManagerInvariantsWithError(cm)
+        self.assertAfterWithGeneratorInvariantsWithError(self.resource)
+
+    def testExceptionNormalized(self):
+        cm = mock_contextmanager_generator()
+        def shouldThrow():
+            with cm as self.resource:
+                # Note this relies on the fact that 1 // 0 produces an exception
+                # that is not normalized immediately.
+                1 // 0
+        self.assertRaises(ZeroDivisionError, shouldThrow)
+        self.assertAfterWithManagerInvariantsWithError(cm, ZeroDivisionError)
+
+    def testNestedSingleStatements(self):
+        mock_a = mock_contextmanager_generator()
+        mock_b = mock_contextmanager_generator()
+        def shouldThrow():
+            with mock_a as self.foo:
+                with mock_b as self.bar:
+                    self.assertInWithManagerInvariants(mock_a)
+                    self.assertInWithManagerInvariants(mock_b)
+                    self.assertInWithGeneratorInvariants(self.foo)
+                    self.assertInWithGeneratorInvariants(self.bar)
+                    self.raiseTestException()
+        self.assertRaises(RuntimeError, shouldThrow)
+        self.assertAfterWithManagerInvariantsWithError(mock_a)
+        self.assertAfterWithManagerInvariantsWithError(mock_b)
+        self.assertAfterWithGeneratorInvariantsWithError(self.foo)
+        self.assertAfterWithGeneratorInvariantsWithError(self.bar)
+
+    def testMultipleResourcesInSingleStatement(self):
+        cm_a = mock_contextmanager_generator()
+        cm_b = mock_contextmanager_generator()
+        mock_nested = MockNested(cm_a, cm_b)
+        def shouldThrow():
+            with mock_nested as (self.resource_a, self.resource_b):
+                self.assertInWithManagerInvariants(cm_a)
+                self.assertInWithManagerInvariants(cm_b)
+                self.assertInWithManagerInvariants(mock_nested)
+                self.assertInWithGeneratorInvariants(self.resource_a)
+                self.assertInWithGeneratorInvariants(self.resource_b)
+                self.raiseTestException()
+        self.assertRaises(RuntimeError, shouldThrow)
+        self.assertAfterWithManagerInvariantsWithError(cm_a)
+        self.assertAfterWithManagerInvariantsWithError(cm_b)
+        self.assertAfterWithManagerInvariantsWithError(mock_nested)
+        self.assertAfterWithGeneratorInvariantsWithError(self.resource_a)
+        self.assertAfterWithGeneratorInvariantsWithError(self.resource_b)
+
+    def testNestedExceptionBeforeInnerStatement(self):
+        mock_a = mock_contextmanager_generator()
+        mock_b = mock_contextmanager_generator()
+        self.bar = None
+        def shouldThrow():
+            with mock_a as self.foo:
+                self.assertInWithManagerInvariants(mock_a)
+                self.assertInWithGeneratorInvariants(self.foo)
+                self.raiseTestException()
+                with mock_b as self.bar:
+                    pass
+        self.assertRaises(RuntimeError, shouldThrow)
+        self.assertAfterWithManagerInvariantsWithError(mock_a)
+        self.assertAfterWithGeneratorInvariantsWithError(self.foo)
+
+        # The inner statement stuff should never have been touched
+        self.assertEqual(self.bar, None)
+        self.assertFalse(mock_b.enter_called)
+        self.assertFalse(mock_b.exit_called)
+        self.assertEqual(mock_b.exit_args, None)
+
+    def testNestedExceptionAfterInnerStatement(self):
+        mock_a = mock_contextmanager_generator()
+        mock_b = mock_contextmanager_generator()
+        def shouldThrow():
+            with mock_a as self.foo:
+                with mock_b as self.bar:
+                    self.assertInWithManagerInvariants(mock_a)
+                    self.assertInWithManagerInvariants(mock_b)
+                    self.assertInWithGeneratorInvariants(self.foo)
+                    self.assertInWithGeneratorInvariants(self.bar)
+                self.raiseTestException()
+        self.assertRaises(RuntimeError, shouldThrow)
+        self.assertAfterWithManagerInvariantsWithError(mock_a)
+        self.assertAfterWithManagerInvariantsNoError(mock_b)
+        self.assertAfterWithGeneratorInvariantsWithError(self.foo)
+        self.assertAfterWithGeneratorInvariantsNoError(self.bar)
+
+    def testRaisedStopIteration1(self):
+        # From bug 1462485
+        @contextmanager
+        def cm():
+            yield
+
+        def shouldThrow():
+            with cm():
+                raise StopIteration("from with")
+
+        with self.assertWarnsRegex(DeprecationWarning, "StopIteration"):
+            self.assertRaises(StopIteration, shouldThrow)
+
+    def testRaisedStopIteration2(self):
+        # From bug 1462485
+        class cm(object):
+            def __enter__(self):
+                pass
+            def __exit__(self, type, value, traceback):
+                pass
+
+        def shouldThrow():
+            with cm():
+                raise StopIteration("from with")
+
+        self.assertRaises(StopIteration, shouldThrow)
+
+    def testRaisedStopIteration3(self):
+        # Another variant where the exception hasn't been instantiated
+        # From bug 1705170
+        @contextmanager
+        def cm():
+            yield
+
+        def shouldThrow():
+            with cm():
+                raise next(iter([]))
+
+        with self.assertWarnsRegex(DeprecationWarning, "StopIteration"):
+            self.assertRaises(StopIteration, shouldThrow)
+
+    def testRaisedGeneratorExit1(self):
+        # From bug 1462485
+        @contextmanager
+        def cm():
+            yield
+
+        def shouldThrow():
+            with cm():
+                raise GeneratorExit("from with")
+
+        self.assertRaises(GeneratorExit, shouldThrow)
+
+    def testRaisedGeneratorExit2(self):
+        # From bug 1462485
+        class cm (object):
+            def __enter__(self):
+                pass
+            def __exit__(self, type, value, traceback):
+                pass
+
+        def shouldThrow():
+            with cm():
+                raise GeneratorExit("from with")
+
+        self.assertRaises(GeneratorExit, shouldThrow)
+
+    def testErrorsInBool(self):
+        # issue4589: __exit__ return code may raise an exception
+        # when looking at its truth value.
+
+        class cm(object):
+            def __init__(self, bool_conversion):
+                class Bool:
+                    def __bool__(self):
+                        return bool_conversion()
+                self.exit_result = Bool()
+            def __enter__(self):
+                return 3
+            def __exit__(self, a, b, c):
+                return self.exit_result
+
+        def trueAsBool():
+            with cm(lambda: True):
+                self.fail("Should NOT see this")
+        trueAsBool()
+
+        def falseAsBool():
+            with cm(lambda: False):
+                self.fail("Should raise")
+        self.assertRaises(AssertionError, falseAsBool)
+
+        def failAsBool():
+            with cm(lambda: 1//0):
+                self.fail("Should NOT see this")
+        self.assertRaises(ZeroDivisionError, failAsBool)
+
+
+class NonLocalFlowControlTestCase(unittest.TestCase):
+
+    def testWithBreak(self):
+        counter = 0
+        while True:
+            counter += 1
+            with mock_contextmanager_generator():
+                counter += 10
+                break
+            counter += 100 # Not reached
+        self.assertEqual(counter, 11)
+
+    def testWithContinue(self):
+        counter = 0
+        while True:
+            counter += 1
+            if counter > 2:
+                break
+            with mock_contextmanager_generator():
+                counter += 10
+                continue
+            counter += 100 # Not reached
+        self.assertEqual(counter, 12)
+
+    def testWithReturn(self):
+        def foo():
+            counter = 0
+            while True:
+                counter += 1
+                with mock_contextmanager_generator():
+                    counter += 10
+                    return counter
+                counter += 100 # Not reached
+        self.assertEqual(foo(), 11)
+
+    def testWithYield(self):
+        def gen():
+            with mock_contextmanager_generator():
+                yield 12
+                yield 13
+        x = list(gen())
+        self.assertEqual(x, [12, 13])
+
+    def testWithRaise(self):
+        counter = 0
+        try:
+            counter += 1
+            with mock_contextmanager_generator():
+                counter += 10
+                raise RuntimeError
+            counter += 100 # Not reached
+        except RuntimeError:
+            self.assertEqual(counter, 11)
+        else:
+            self.fail("Didn't raise RuntimeError")
+
+
+class AssignmentTargetTestCase(unittest.TestCase):
+
+    def testSingleComplexTarget(self):
+        targets = {1: [0, 1, 2]}
+        with mock_contextmanager_generator() as targets[1][0]:
+            self.assertEqual(list(targets.keys()), [1])
+            self.assertEqual(targets[1][0].__class__, MockResource)
+        with mock_contextmanager_generator() as list(targets.values())[0][1]:
+            self.assertEqual(list(targets.keys()), [1])
+            self.assertEqual(targets[1][1].__class__, MockResource)
+        with mock_contextmanager_generator() as targets[2]:
+            keys = list(targets.keys())
+            keys.sort()
+            self.assertEqual(keys, [1, 2])
+        class C: pass
+        blah = C()
+        with mock_contextmanager_generator() as blah.foo:
+            self.assertEqual(hasattr(blah, "foo"), True)
+
+    def testMultipleComplexTargets(self):
+        class C:
+            def __enter__(self): return 1, 2, 3
+            def __exit__(self, t, v, tb): pass
+        targets = {1: [0, 1, 2]}
+        with C() as (targets[1][0], targets[1][1], targets[1][2]):
+            self.assertEqual(targets, {1: [1, 2, 3]})
+        with C() as (list(targets.values())[0][2], list(targets.values())[0][1], list(targets.values())[0][0]):
+            self.assertEqual(targets, {1: [3, 2, 1]})
+        with C() as (targets[1], targets[2], targets[3]):
+            self.assertEqual(targets, {1: 1, 2: 2, 3: 3})
+        class B: pass
+        blah = B()
+        with C() as (blah.one, blah.two, blah.three):
+            self.assertEqual(blah.one, 1)
+            self.assertEqual(blah.two, 2)
+            self.assertEqual(blah.three, 3)
+
+
+class ExitSwallowsExceptionTestCase(unittest.TestCase):
+
+    def testExitTrueSwallowsException(self):
+        class AfricanSwallow:
+            def __enter__(self): pass
+            def __exit__(self, t, v, tb): return True
+        try:
+            with AfricanSwallow():
+                1/0
+        except ZeroDivisionError:
+            self.fail("ZeroDivisionError should have been swallowed")
+
+    def testExitFalseDoesntSwallowException(self):
+        class EuropeanSwallow:
+            def __enter__(self): pass
+            def __exit__(self, t, v, tb): return False
+        try:
+            with EuropeanSwallow():
+                1/0
+        except ZeroDivisionError:
+            pass
+        else:
+            self.fail("ZeroDivisionError should have been raised")
+
+
+class NestedWith(unittest.TestCase):
+
+    class Dummy(object):
+        def __init__(self, value=None, gobble=False):
+            if value is None:
+                value = self
+            self.value = value
+            self.gobble = gobble
+            self.enter_called = False
+            self.exit_called = False
+
+        def __enter__(self):
+            self.enter_called = True
+            return self.value
+
+        def __exit__(self, *exc_info):
+            self.exit_called = True
+            self.exc_info = exc_info
+            if self.gobble:
+                return True
+
+    class InitRaises(object):
+        def __init__(self): raise RuntimeError()
+
+    class EnterRaises(object):
+        def __enter__(self): raise RuntimeError()
+        def __exit__(self, *exc_info): pass
+
+    class ExitRaises(object):
+        def __enter__(self): pass
+        def __exit__(self, *exc_info): raise RuntimeError()
+
+    def testNoExceptions(self):
+        with self.Dummy() as a, self.Dummy() as b:
+            self.assertTrue(a.enter_called)
+            self.assertTrue(b.enter_called)
+        self.assertTrue(a.exit_called)
+        self.assertTrue(b.exit_called)
+
+    def testExceptionInExprList(self):
+        try:
+            with self.Dummy() as a, self.InitRaises():
+                pass
+        except:
+            pass
+        self.assertTrue(a.enter_called)
+        self.assertTrue(a.exit_called)
+
+    def testExceptionInEnter(self):
+        try:
+            with self.Dummy() as a, self.EnterRaises():
+                self.fail('body of bad with executed')
+        except RuntimeError:
+            pass
+        else:
+            self.fail('RuntimeError not reraised')
+        self.assertTrue(a.enter_called)
+        self.assertTrue(a.exit_called)
+
+    def testExceptionInExit(self):
+        body_executed = False
+        with self.Dummy(gobble=True) as a, self.ExitRaises():
+            body_executed = True
+        self.assertTrue(a.enter_called)
+        self.assertTrue(a.exit_called)
+        self.assertTrue(body_executed)
+        self.assertNotEqual(a.exc_info[0], None)
+
+    def testEnterReturnsTuple(self):
+        with self.Dummy(value=(1,2)) as (a1, a2), \
+             self.Dummy(value=(10, 20)) as (b1, b2):
+            self.assertEqual(1, a1)
+            self.assertEqual(2, a2)
+            self.assertEqual(10, b1)
+            self.assertEqual(20, b2)
+
+if __name__ == '__main__':
+    unittest.main()