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diff --git a/contrib/python/zope.interface/py2/zope/interface/tests/test_declarations.py b/contrib/python/zope.interface/py2/zope/interface/tests/test_declarations.py
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+++ b/contrib/python/zope.interface/py2/zope/interface/tests/test_declarations.py
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+##############################################################################
+#
+# Copyright (c) 2003 Zope Foundation and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+##############################################################################
+"""Test the new API for making and checking interface declarations
+"""
+import unittest
+
+from zope.interface._compat import _skip_under_py3k
+from zope.interface._compat import PYTHON3
+from __tests__.tests import OptimizationTestMixin
+from __tests__.tests import MissingSomeAttrs
+from __tests__.tests.test_interface import NameAndModuleComparisonTestsMixin
+
+# pylint:disable=inherit-non-class,too-many-lines,protected-access
+# pylint:disable=blacklisted-name,attribute-defined-outside-init
+
+class _Py3ClassAdvice(object):
+
+    def _run_generated_code(self, code, globs, locs,
+                            fails_under_py3k=True,
+                           ):
+        # pylint:disable=exec-used,no-member
+        import warnings
+        with warnings.catch_warnings(record=True) as log:
+            warnings.resetwarnings()
+            if not PYTHON3:
+                exec(code, globs, locs)
+                self.assertEqual(len(log), 0) # no longer warn
+                return True
+
+            try:
+                exec(code, globs, locs)
+            except TypeError:
+                return False
+            else:
+                if fails_under_py3k:
+                    self.fail("Didn't raise TypeError")
+            return None
+
+
+class NamedTests(unittest.TestCase):
+
+    def test_class(self):
+        from zope.interface.declarations import named
+
+        @named(u'foo')
+        class Foo(object):
+            pass
+
+        self.assertEqual(Foo.__component_name__, u'foo') # pylint:disable=no-member
+
+    def test_function(self):
+        from zope.interface.declarations import named
+
+        @named(u'foo')
+        def doFoo(o):
+            raise NotImplementedError()
+
+        self.assertEqual(doFoo.__component_name__, u'foo')
+
+    def test_instance(self):
+        from zope.interface.declarations import named
+
+        class Foo(object):
+            pass
+        foo = Foo()
+        named(u'foo')(foo)
+
+        self.assertEqual(foo.__component_name__, u'foo') # pylint:disable=no-member
+
+
+class EmptyDeclarationTests(unittest.TestCase):
+    # Tests that should pass for all objects that are empty
+    # declarations. This includes a Declaration explicitly created
+    # that way, and the empty ImmutableDeclaration.
+    def _getEmpty(self):
+        from zope.interface.declarations import Declaration
+        return Declaration()
+
+    def test___iter___empty(self):
+        decl = self._getEmpty()
+        self.assertEqual(list(decl), [])
+
+    def test_flattened_empty(self):
+        from zope.interface.interface import Interface
+        decl = self._getEmpty()
+        self.assertEqual(list(decl.flattened()), [Interface])
+
+    def test___contains___empty(self):
+        from zope.interface.interface import Interface
+        decl = self._getEmpty()
+        self.assertNotIn(Interface, decl)
+
+    def test_extends_empty(self):
+        from zope.interface.interface import Interface
+        decl = self._getEmpty()
+        self.assertTrue(decl.extends(Interface))
+        self.assertTrue(decl.extends(Interface, strict=True))
+
+    def test_interfaces_empty(self):
+        decl = self._getEmpty()
+        l = list(decl.interfaces())
+        self.assertEqual(l, [])
+
+    def test___sro___(self):
+        from zope.interface.interface import Interface
+        decl = self._getEmpty()
+        self.assertEqual(decl.__sro__, (decl, Interface,))
+
+    def test___iro___(self):
+        from zope.interface.interface import Interface
+        decl = self._getEmpty()
+        self.assertEqual(decl.__iro__, (Interface,))
+
+    def test_get(self):
+        decl = self._getEmpty()
+        self.assertIsNone(decl.get('attr'))
+        self.assertEqual(decl.get('abc', 'def'), 'def')
+        # It's a positive cache only (when it even exists)
+        # so this added nothing.
+        self.assertFalse(decl._v_attrs)
+
+    def test_changed_w_existing__v_attrs(self):
+        decl = self._getEmpty()
+        decl._v_attrs = object()
+        decl.changed(decl)
+        self.assertFalse(decl._v_attrs)
+
+
+class DeclarationTests(EmptyDeclarationTests):
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import Declaration
+        return Declaration
+
+    def _makeOne(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def test_ctor_no_bases(self):
+        decl = self._makeOne()
+        self.assertEqual(list(decl.__bases__), [])
+
+    def test_ctor_w_interface_in_bases(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        decl = self._makeOne(IFoo)
+        self.assertEqual(list(decl.__bases__), [IFoo])
+
+    def test_ctor_w_implements_in_bases(self):
+        from zope.interface.declarations import Implements
+        impl = Implements()
+        decl = self._makeOne(impl)
+        self.assertEqual(list(decl.__bases__), [impl])
+
+    def test_changed_wo_existing__v_attrs(self):
+        decl = self._makeOne()
+        decl.changed(decl) # doesn't raise
+        self.assertIsNone(decl._v_attrs)
+
+    def test___contains__w_self(self):
+        decl = self._makeOne()
+        self.assertNotIn(decl, decl)
+
+    def test___contains__w_unrelated_iface(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        decl = self._makeOne()
+        self.assertNotIn(IFoo, decl)
+
+    def test___contains__w_base_interface(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        decl = self._makeOne(IFoo)
+        self.assertIn(IFoo, decl)
+
+    def test___iter___single_base(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        decl = self._makeOne(IFoo)
+        self.assertEqual(list(decl), [IFoo])
+
+    def test___iter___multiple_bases(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar')
+        decl = self._makeOne(IFoo, IBar)
+        self.assertEqual(list(decl), [IFoo, IBar])
+
+    def test___iter___inheritance(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar', (IFoo,))
+        decl = self._makeOne(IBar)
+        self.assertEqual(list(decl), [IBar]) #IBar.interfaces() omits bases
+
+    def test___iter___w_nested_sequence_overlap(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar')
+        decl = self._makeOne(IBar, (IFoo, IBar))
+        self.assertEqual(list(decl), [IBar, IFoo])
+
+    def test_flattened_single_base(self):
+        from zope.interface.interface import Interface
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        decl = self._makeOne(IFoo)
+        self.assertEqual(list(decl.flattened()), [IFoo, Interface])
+
+    def test_flattened_multiple_bases(self):
+        from zope.interface.interface import Interface
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar')
+        decl = self._makeOne(IFoo, IBar)
+        self.assertEqual(list(decl.flattened()), [IFoo, IBar, Interface])
+
+    def test_flattened_inheritance(self):
+        from zope.interface.interface import Interface
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar', (IFoo,))
+        decl = self._makeOne(IBar)
+        self.assertEqual(list(decl.flattened()), [IBar, IFoo, Interface])
+
+    def test_flattened_w_nested_sequence_overlap(self):
+        from zope.interface.interface import Interface
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar')
+        # This is the same as calling ``Declaration(IBar, IFoo, IBar)``
+        # which doesn't make much sense, but here it is. In older
+        # versions of zope.interface, the __iro__ would have been
+        # IFoo, IBar, Interface, which especially makes no sense.
+        decl = self._makeOne(IBar, (IFoo, IBar))
+        # Note that decl.__iro__ has IFoo first.
+        self.assertEqual(list(decl.flattened()), [IBar, IFoo, Interface])
+
+    def test___sub___unrelated_interface(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar')
+        before = self._makeOne(IFoo)
+        after = before - IBar
+        self.assertIsInstance(after, self._getTargetClass())
+        self.assertEqual(list(after), [IFoo])
+
+    def test___sub___related_interface(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        before = self._makeOne(IFoo)
+        after = before - IFoo
+        self.assertEqual(list(after), [])
+
+    def test___sub___related_interface_by_inheritance(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar', (IFoo,))
+        before = self._makeOne(IBar)
+        after = before - IBar
+        self.assertEqual(list(after), [])
+
+    def test___add___unrelated_interface(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar')
+        before = self._makeOne(IFoo)
+        after = before + IBar
+        self.assertIsInstance(after, self._getTargetClass())
+        self.assertEqual(list(after), [IFoo, IBar])
+
+    def test___add___related_interface(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar')
+        IBaz = InterfaceClass('IBaz')
+        before = self._makeOne(IFoo, IBar)
+        other = self._makeOne(IBar, IBaz)
+        after = before + other
+        self.assertEqual(list(after), [IFoo, IBar, IBaz])
+
+    def test___add___overlapping_interface(self):
+        # The derived interfaces end up with higher priority, and
+        # don't produce a C3 resolution order violation. This
+        # example produced a C3 error, and the resulting legacy order
+        # used to be wrong ([IBase, IDerived] instead of
+        # the other way).
+        from zope.interface import Interface
+        from zope.interface.interface import InterfaceClass
+        from __tests__.tests.test_ro import C3Setting
+        from zope.interface import ro
+
+        IBase = InterfaceClass('IBase')
+        IDerived = InterfaceClass('IDerived', (IBase,))
+
+        with C3Setting(ro.C3.STRICT_IRO, True):
+            base = self._makeOne(IBase)
+            after = base + IDerived
+
+        self.assertEqual(after.__iro__, (IDerived, IBase, Interface))
+        self.assertEqual(after.__bases__, (IDerived, IBase))
+        self.assertEqual(list(after), [IDerived, IBase])
+
+    def test___add___overlapping_interface_implementedBy(self):
+        # Like test___add___overlapping_interface, but pulling
+        # in a realistic example. This one previously produced a
+        # C3 error, but the resulting legacy order was (somehow)
+        # correct.
+        from zope.interface import Interface
+        from zope.interface import implementedBy
+        from zope.interface import implementer
+        from __tests__.tests.test_ro import C3Setting
+        from zope.interface import ro
+
+        class IBase(Interface):
+            pass
+
+        class IDerived(IBase):
+            pass
+
+        @implementer(IBase)
+        class Base(object):
+            pass
+
+        with C3Setting(ro.C3.STRICT_IRO, True):
+            after = implementedBy(Base) + IDerived
+
+        self.assertEqual(after.__sro__, (after, IDerived, IBase, Interface))
+        self.assertEqual(after.__bases__, (IDerived, IBase))
+        self.assertEqual(list(after), [IDerived, IBase])
+
+
+class TestImmutableDeclaration(EmptyDeclarationTests):
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import _ImmutableDeclaration
+        return _ImmutableDeclaration
+
+    def _getEmpty(self):
+        from zope.interface.declarations import _empty
+        return _empty
+
+    def test_pickle(self):
+        import pickle
+        copied = pickle.loads(pickle.dumps(self._getEmpty()))
+        self.assertIs(copied, self._getEmpty())
+
+    def test_singleton(self):
+        self.assertIs(
+            self._getTargetClass()(),
+            self._getEmpty()
+        )
+
+    def test__bases__(self):
+        self.assertEqual(self._getEmpty().__bases__, ())
+
+    def test_change__bases__(self):
+        empty = self._getEmpty()
+        empty.__bases__ = ()
+        self.assertEqual(self._getEmpty().__bases__, ())
+
+        with self.assertRaises(TypeError):
+            empty.__bases__ = (1,)
+
+    def test_dependents(self):
+        empty = self._getEmpty()
+        deps = empty.dependents
+        self.assertEqual({}, deps)
+        # Doesn't change the return.
+        deps[1] = 2
+        self.assertEqual({}, empty.dependents)
+
+    def test_changed(self):
+        # Does nothing, has no visible side-effects
+        self._getEmpty().changed(None)
+
+    def test_extends_always_false(self):
+        self.assertFalse(self._getEmpty().extends(self))
+        self.assertFalse(self._getEmpty().extends(self, strict=True))
+        self.assertFalse(self._getEmpty().extends(self, strict=False))
+
+    def test_get_always_default(self):
+        self.assertIsNone(self._getEmpty().get('name'))
+        self.assertEqual(self._getEmpty().get('name', 42), 42)
+
+    def test_v_attrs(self):
+        decl = self._getEmpty()
+        self.assertEqual(decl._v_attrs, {})
+
+        decl._v_attrs['attr'] = 42
+        self.assertEqual(decl._v_attrs, {})
+        self.assertIsNone(decl.get('attr'))
+
+        attrs = decl._v_attrs = {}
+        attrs['attr'] = 42
+        self.assertEqual(decl._v_attrs, {})
+        self.assertIsNone(decl.get('attr'))
+
+
+class TestImplements(NameAndModuleComparisonTestsMixin,
+                     unittest.TestCase):
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import Implements
+        return Implements
+
+    def _makeOne(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def _makeOneToCompare(self):
+        from zope.interface.declarations import implementedBy
+        class A(object):
+            pass
+
+        return implementedBy(A)
+
+    def test_ctor_no_bases(self):
+        impl = self._makeOne()
+        self.assertEqual(impl.inherit, None)
+        self.assertEqual(impl.declared, ())
+        self.assertEqual(impl.__name__, '?')
+        self.assertEqual(list(impl.__bases__), [])
+
+    def test___repr__(self):
+        impl = self._makeOne()
+        impl.__name__ = 'Testing'
+        self.assertEqual(repr(impl), 'classImplements(Testing)')
+
+    def test___reduce__(self):
+        from zope.interface.declarations import implementedBy
+        impl = self._makeOne()
+        self.assertEqual(impl.__reduce__(), (implementedBy, (None,)))
+
+    def test_sort(self):
+        from zope.interface.declarations import implementedBy
+        class A(object):
+            pass
+        class B(object):
+            pass
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+
+        self.assertEqual(implementedBy(A), implementedBy(A))
+        self.assertEqual(hash(implementedBy(A)), hash(implementedBy(A)))
+        self.assertTrue(implementedBy(A) < None)
+        self.assertTrue(None > implementedBy(A)) # pylint:disable=misplaced-comparison-constant
+        self.assertTrue(implementedBy(A) < implementedBy(B))
+        self.assertTrue(implementedBy(A) > IFoo)
+        self.assertTrue(implementedBy(A) <= implementedBy(B))
+        self.assertTrue(implementedBy(A) >= IFoo)
+        self.assertTrue(implementedBy(A) != IFoo)
+
+    def test_proxy_equality(self):
+        # https://github.com/zopefoundation/zope.interface/issues/55
+        class Proxy(object):
+            def __init__(self, wrapped):
+                self._wrapped = wrapped
+
+            def __getattr__(self, name):
+                raise NotImplementedError()
+
+            def __eq__(self, other):
+                return self._wrapped == other
+
+            def __ne__(self, other):
+                return self._wrapped != other
+
+        from zope.interface.declarations import implementedBy
+        class A(object):
+            pass
+
+        class B(object):
+            pass
+
+        implementedByA = implementedBy(A)
+        implementedByB = implementedBy(B)
+        proxy = Proxy(implementedByA)
+
+        # The order of arguments to the operators matters,
+        # test both
+        self.assertTrue(implementedByA == implementedByA) # pylint:disable=comparison-with-itself
+        self.assertTrue(implementedByA != implementedByB)
+        self.assertTrue(implementedByB != implementedByA)
+
+        self.assertTrue(proxy == implementedByA)
+        self.assertTrue(implementedByA == proxy)
+        self.assertFalse(proxy != implementedByA)
+        self.assertFalse(implementedByA != proxy)
+
+        self.assertTrue(proxy != implementedByB)
+        self.assertTrue(implementedByB != proxy)
+
+    def test_changed_deletes_super_cache(self):
+        impl = self._makeOne()
+        self.assertIsNone(impl._super_cache)
+        self.assertNotIn('_super_cache', impl.__dict__)
+
+        impl._super_cache = 42
+        self.assertIn('_super_cache', impl.__dict__)
+
+        impl.changed(None)
+        self.assertIsNone(impl._super_cache)
+        self.assertNotIn('_super_cache', impl.__dict__)
+
+    def test_changed_does_not_add_super_cache(self):
+        impl = self._makeOne()
+        self.assertIsNone(impl._super_cache)
+        self.assertNotIn('_super_cache', impl.__dict__)
+
+        impl.changed(None)
+        self.assertIsNone(impl._super_cache)
+        self.assertNotIn('_super_cache', impl.__dict__)
+
+
+class Test_implementedByFallback(unittest.TestCase):
+
+    def _getTargetClass(self):
+        # pylint:disable=no-name-in-module
+        from zope.interface.declarations import implementedByFallback
+        return implementedByFallback
+
+    _getFallbackClass = _getTargetClass
+
+    def _callFUT(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def test_dictless_wo_existing_Implements_wo_registrations(self):
+        class Foo(object):
+            __slots__ = ('__implemented__',)
+        foo = Foo()
+        foo.__implemented__ = None
+        self.assertEqual(list(self._callFUT(foo)), [])
+
+    def test_dictless_wo_existing_Implements_cant_assign___implemented__(self):
+        class Foo(object):
+            def _get_impl(self):
+                raise NotImplementedError()
+            def _set_impl(self, val):
+                raise TypeError
+            __implemented__ = property(_get_impl, _set_impl)
+            def __call__(self):
+                # act like a factory
+                raise NotImplementedError()
+        foo = Foo()
+        self.assertRaises(TypeError, self._callFUT, foo)
+
+    def test_dictless_wo_existing_Implements_w_registrations(self):
+        from zope.interface import declarations
+        class Foo(object):
+            __slots__ = ('__implemented__',)
+        foo = Foo()
+        foo.__implemented__ = None
+        reg = object()
+        with _MonkeyDict(declarations,
+                         'BuiltinImplementationSpecifications') as specs:
+            specs[foo] = reg
+            self.assertTrue(self._callFUT(foo) is reg)
+
+    def test_dictless_w_existing_Implements(self):
+        from zope.interface.declarations import Implements
+        impl = Implements()
+        class Foo(object):
+            __slots__ = ('__implemented__',)
+        foo = Foo()
+        foo.__implemented__ = impl
+        self.assertTrue(self._callFUT(foo) is impl)
+
+    def test_dictless_w_existing_not_Implements(self):
+        from zope.interface.interface import InterfaceClass
+        class Foo(object):
+            __slots__ = ('__implemented__',)
+        foo = Foo()
+        IFoo = InterfaceClass('IFoo')
+        foo.__implemented__ = (IFoo,)
+        self.assertEqual(list(self._callFUT(foo)), [IFoo])
+
+    def test_w_existing_attr_as_Implements(self):
+        from zope.interface.declarations import Implements
+        impl = Implements()
+        class Foo(object):
+            __implemented__ = impl
+        self.assertTrue(self._callFUT(Foo) is impl)
+
+    def test_builtins_added_to_cache(self):
+        from zope.interface import declarations
+        from zope.interface.declarations import Implements
+        with _MonkeyDict(declarations,
+                         'BuiltinImplementationSpecifications') as specs:
+            self.assertEqual(list(self._callFUT(tuple)), [])
+            self.assertEqual(list(self._callFUT(list)), [])
+            self.assertEqual(list(self._callFUT(dict)), [])
+            for typ in (tuple, list, dict):
+                spec = specs[typ]
+                self.assertIsInstance(spec, Implements)
+                self.assertEqual(repr(spec),
+                                 'classImplements(%s)'
+                                 % (typ.__name__,))
+
+    def test_builtins_w_existing_cache(self):
+        from zope.interface import declarations
+        t_spec, l_spec, d_spec = object(), object(), object()
+        with _MonkeyDict(declarations,
+                         'BuiltinImplementationSpecifications') as specs:
+            specs[tuple] = t_spec
+            specs[list] = l_spec
+            specs[dict] = d_spec
+            self.assertTrue(self._callFUT(tuple) is t_spec)
+            self.assertTrue(self._callFUT(list) is l_spec)
+            self.assertTrue(self._callFUT(dict) is d_spec)
+
+    def test_oldstyle_class_no_assertions(self):
+        # TODO: Figure out P3 story
+        class Foo:
+            pass
+        self.assertEqual(list(self._callFUT(Foo)), [])
+
+    def test_no_assertions(self):
+        # TODO: Figure out P3 story
+        class Foo(object):
+            pass
+        self.assertEqual(list(self._callFUT(Foo)), [])
+
+    def test_w_None_no_bases_not_factory(self):
+        class Foo(object):
+            __implemented__ = None
+        foo = Foo()
+        self.assertRaises(TypeError, self._callFUT, foo)
+
+    def test_w_None_no_bases_w_factory(self):
+        from zope.interface.declarations import objectSpecificationDescriptor
+        class Foo(object):
+            __implemented__ = None
+            def __call__(self):
+                raise NotImplementedError()
+
+        foo = Foo()
+        foo.__name__ = 'foo'
+        spec = self._callFUT(foo)
+        self.assertEqual(spec.__name__,
+                         '__tests__.tests.test_declarations.foo')
+        self.assertIs(spec.inherit, foo)
+        self.assertIs(foo.__implemented__, spec)
+        self.assertIs(foo.__providedBy__, objectSpecificationDescriptor) # pylint:disable=no-member
+        self.assertNotIn('__provides__', foo.__dict__)
+
+    def test_w_None_no_bases_w_class(self):
+        from zope.interface.declarations import ClassProvides
+        class Foo(object):
+            __implemented__ = None
+        spec = self._callFUT(Foo)
+        self.assertEqual(spec.__name__,
+                         '__tests__.tests.test_declarations.Foo')
+        self.assertIs(spec.inherit, Foo)
+        self.assertIs(Foo.__implemented__, spec)
+        self.assertIsInstance(Foo.__providedBy__, ClassProvides) # pylint:disable=no-member
+        self.assertIsInstance(Foo.__provides__, ClassProvides) # pylint:disable=no-member
+        self.assertEqual(Foo.__provides__, Foo.__providedBy__) # pylint:disable=no-member
+
+    def test_w_existing_Implements(self):
+        from zope.interface.declarations import Implements
+        impl = Implements()
+        class Foo(object):
+            __implemented__ = impl
+        self.assertTrue(self._callFUT(Foo) is impl)
+
+    def test_super_when_base_implements_interface(self):
+        from zope.interface import Interface
+        from zope.interface.declarations import implementer
+
+        class IBase(Interface):
+            pass
+
+        class IDerived(IBase):
+            pass
+
+        @implementer(IBase)
+        class Base(object):
+            pass
+
+        @implementer(IDerived)
+        class Derived(Base):
+            pass
+
+        self.assertEqual(list(self._callFUT(Derived)), [IDerived, IBase])
+        sup = super(Derived, Derived)
+        self.assertEqual(list(self._callFUT(sup)), [IBase])
+
+    def test_super_when_base_implements_interface_diamond(self):
+        from zope.interface import Interface
+        from zope.interface.declarations import implementer
+
+        class IBase(Interface):
+            pass
+
+        class IDerived(IBase):
+            pass
+
+        @implementer(IBase)
+        class Base(object):
+            pass
+
+        class Child1(Base):
+            pass
+
+        class Child2(Base):
+            pass
+
+        @implementer(IDerived)
+        class Derived(Child1, Child2):
+            pass
+
+        self.assertEqual(list(self._callFUT(Derived)), [IDerived, IBase])
+        sup = super(Derived, Derived)
+        self.assertEqual(list(self._callFUT(sup)), [IBase])
+
+    def test_super_when_parent_implements_interface_diamond(self):
+        from zope.interface import Interface
+        from zope.interface.declarations import implementer
+
+        class IBase(Interface):
+            pass
+
+        class IDerived(IBase):
+            pass
+
+
+        class Base(object):
+            pass
+
+        class Child1(Base):
+            pass
+
+        @implementer(IBase)
+        class Child2(Base):
+            pass
+
+        @implementer(IDerived)
+        class Derived(Child1, Child2):
+            pass
+
+        self.assertEqual(Derived.__mro__, (Derived, Child1, Child2, Base, object))
+        self.assertEqual(list(self._callFUT(Derived)), [IDerived, IBase])
+        sup = super(Derived, Derived)
+        fut = self._callFUT(sup)
+        self.assertEqual(list(fut), [IBase])
+        self.assertIsNone(fut._dependents)
+
+    def test_super_when_base_doesnt_implement_interface(self):
+        from zope.interface import Interface
+        from zope.interface.declarations import implementer
+
+        class IBase(Interface):
+            pass
+
+        class IDerived(IBase):
+            pass
+
+        class Base(object):
+            pass
+
+        @implementer(IDerived)
+        class Derived(Base):
+            pass
+
+        self.assertEqual(list(self._callFUT(Derived)), [IDerived])
+
+        sup = super(Derived, Derived)
+        self.assertEqual(list(self._callFUT(sup)), [])
+
+    def test_super_when_base_is_object(self):
+        from zope.interface import Interface
+        from zope.interface.declarations import implementer
+
+        class IBase(Interface):
+            pass
+
+        class IDerived(IBase):
+            pass
+
+        @implementer(IDerived)
+        class Derived(object):
+            pass
+
+        self.assertEqual(list(self._callFUT(Derived)), [IDerived])
+
+        sup = super(Derived, Derived)
+        self.assertEqual(list(self._callFUT(sup)), [])
+    def test_super_multi_level_multi_inheritance(self):
+        from zope.interface.declarations import implementer
+        from zope.interface import Interface
+
+        class IBase(Interface):
+            pass
+
+        class IM1(Interface):
+            pass
+
+        class IM2(Interface):
+            pass
+
+        class IDerived(IBase):
+            pass
+
+        class IUnrelated(Interface):
+            pass
+
+        @implementer(IBase)
+        class Base(object):
+            pass
+
+        @implementer(IM1)
+        class M1(Base):
+            pass
+
+        @implementer(IM2)
+        class M2(Base):
+            pass
+
+        @implementer(IDerived, IUnrelated)
+        class Derived(M1, M2):
+            pass
+
+        d = Derived
+        sd = super(Derived, Derived)
+        sm1 = super(M1, Derived)
+        sm2 = super(M2, Derived)
+
+        self.assertEqual(list(self._callFUT(d)),
+                         [IDerived, IUnrelated, IM1, IBase, IM2])
+        self.assertEqual(list(self._callFUT(sd)),
+                         [IM1, IBase, IM2])
+        self.assertEqual(list(self._callFUT(sm1)),
+                         [IM2, IBase])
+        self.assertEqual(list(self._callFUT(sm2)),
+                         [IBase])
+
+
+class Test_implementedBy(Test_implementedByFallback,
+                         OptimizationTestMixin):
+    # Repeat tests for C optimizations
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import implementedBy
+        return implementedBy
+
+
+class _ImplementsTestMixin(object):
+    FUT_SETS_PROVIDED_BY = True
+
+    def _callFUT(self, cls, iface):
+        # Declare that *cls* implements *iface*; return *cls*
+        raise NotImplementedError
+
+    def _check_implementer(self, Foo,
+                           orig_spec=None,
+                           spec_name=__name__ + '.Foo',
+                           inherit="not given"):
+        from zope.interface.declarations import ClassProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+
+        returned = self._callFUT(Foo, IFoo)
+
+        self.assertIs(returned, Foo)
+        spec = Foo.__implemented__
+        if orig_spec is not None:
+            self.assertIs(spec, orig_spec)
+
+        self.assertEqual(spec.__name__,
+                         spec_name)
+        inherit = Foo if inherit == "not given" else inherit
+        self.assertIs(spec.inherit, inherit)
+        self.assertIs(Foo.__implemented__, spec)
+        if self.FUT_SETS_PROVIDED_BY:
+            self.assertIsInstance(Foo.__providedBy__, ClassProvides)
+            self.assertIsInstance(Foo.__provides__, ClassProvides)
+            self.assertEqual(Foo.__provides__, Foo.__providedBy__)
+
+        return Foo, IFoo
+
+    def test_oldstyle_class(self):
+        # This only matters on Python 2
+        class Foo:
+            pass
+        self._check_implementer(Foo)
+
+    def test_newstyle_class(self):
+        class Foo(object):
+            pass
+        self._check_implementer(Foo)
+
+class Test_classImplementsOnly(_ImplementsTestMixin, unittest.TestCase):
+    FUT_SETS_PROVIDED_BY = False
+
+    def _callFUT(self, cls, iface):
+        from zope.interface.declarations import classImplementsOnly
+        classImplementsOnly(cls, iface)
+        return cls
+
+    def test_w_existing_Implements(self):
+        from zope.interface.declarations import Implements
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar')
+        impl = Implements(IFoo)
+        impl.declared = (IFoo,)
+        class Foo(object):
+            __implemented__ = impl
+        impl.inherit = Foo
+        self._callFUT(Foo, IBar)
+        # Same spec, now different values
+        self.assertTrue(Foo.__implemented__ is impl)
+        self.assertEqual(impl.inherit, None)
+        self.assertEqual(impl.declared, (IBar,))
+
+    def test_oldstyle_class(self):
+        from zope.interface.declarations import Implements
+        from zope.interface.interface import InterfaceClass
+        IBar = InterfaceClass('IBar')
+        old_spec = Implements(IBar)
+
+        class Foo:
+            __implemented__ = old_spec
+        self._check_implementer(Foo, old_spec, '?', inherit=None)
+
+    def test_newstyle_class(self):
+        from zope.interface.declarations import Implements
+        from zope.interface.interface import InterfaceClass
+        IBar = InterfaceClass('IBar')
+        old_spec = Implements(IBar)
+
+        class Foo(object):
+            __implemented__ = old_spec
+        self._check_implementer(Foo, old_spec, '?', inherit=None)
+
+
+    def test_redundant_with_super_still_implements(self):
+        Base, IBase = self._check_implementer(
+            type('Foo', (object,), {}),
+            inherit=None,
+        )
+
+        class Child(Base):
+            pass
+
+        self._callFUT(Child, IBase)
+        self.assertTrue(IBase.implementedBy(Child))
+
+
+class Test_classImplements(_ImplementsTestMixin, unittest.TestCase):
+
+    def _callFUT(self, cls, iface):
+        from zope.interface.declarations import classImplements
+        result = classImplements(cls, iface) # pylint:disable=assignment-from-no-return
+        self.assertIsNone(result)
+        return cls
+
+    def __check_implementer_redundant(self, Base):
+        # If we @implementer exactly what was already present, we write
+        # no declared attributes on the parent (we still set everything, though)
+        Base, IBase = self._check_implementer(Base)
+
+        class Child(Base):
+            pass
+
+        returned = self._callFUT(Child, IBase)
+        self.assertIn('__implemented__', returned.__dict__)
+        self.assertNotIn('__providedBy__', returned.__dict__)
+        self.assertIn('__provides__', returned.__dict__)
+
+        spec = Child.__implemented__
+        self.assertEqual(spec.declared, ())
+        self.assertEqual(spec.inherit, Child)
+
+        self.assertTrue(IBase.providedBy(Child()))
+
+    def test_redundant_implementer_empty_class_declarations_newstyle(self):
+        self.__check_implementer_redundant(type('Foo', (object,), {}))
+
+    def test_redundant_implementer_empty_class_declarations_oldstyle(self):
+        # This only matters on Python 2
+        class Foo:
+            pass
+        self.__check_implementer_redundant(Foo)
+
+    def test_redundant_implementer_Interface(self):
+        from zope.interface import Interface
+        from zope.interface import implementedBy
+        from zope.interface import ro
+        from __tests__.tests.test_ro import C3Setting
+
+        class Foo(object):
+            pass
+
+        with C3Setting(ro.C3.STRICT_IRO, False):
+            self._callFUT(Foo, Interface)
+            self.assertEqual(list(implementedBy(Foo)), [Interface])
+
+            class Baz(Foo):
+                pass
+
+            self._callFUT(Baz, Interface)
+            self.assertEqual(list(implementedBy(Baz)), [Interface])
+
+    def _order_for_two(self, applied_first, applied_second):
+        return (applied_first, applied_second)
+
+    def test_w_existing_Implements(self):
+        from zope.interface.declarations import Implements
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar')
+        impl = Implements(IFoo)
+        impl.declared = (IFoo,)
+        class Foo(object):
+            __implemented__ = impl
+        impl.inherit = Foo
+        self._callFUT(Foo, IBar)
+        # Same spec, now different values
+        self.assertIs(Foo.__implemented__, impl)
+        self.assertEqual(impl.inherit, Foo)
+        self.assertEqual(impl.declared,
+                         self._order_for_two(IFoo, IBar))
+
+    def test_w_existing_Implements_w_bases(self):
+        from zope.interface.declarations import Implements
+        from zope.interface.interface import InterfaceClass
+        IRoot = InterfaceClass('IRoot')
+        ISecondRoot = InterfaceClass('ISecondRoot')
+        IExtendsRoot = InterfaceClass('IExtendsRoot', (IRoot,))
+
+        impl_root = Implements.named('Root', IRoot)
+        impl_root.declared = (IRoot,)
+
+        class Root1(object):
+            __implemented__ = impl_root
+        class Root2(object):
+            __implemented__ = impl_root
+
+        impl_extends_root = Implements.named('ExtendsRoot1', IExtendsRoot)
+        impl_extends_root.declared = (IExtendsRoot,)
+        class ExtendsRoot(Root1, Root2):
+            __implemented__ = impl_extends_root
+        impl_extends_root.inherit = ExtendsRoot
+
+        self._callFUT(ExtendsRoot, ISecondRoot)
+        # Same spec, now different values
+        self.assertIs(ExtendsRoot.__implemented__, impl_extends_root)
+        self.assertEqual(impl_extends_root.inherit, ExtendsRoot)
+        self.assertEqual(impl_extends_root.declared,
+                         self._order_for_two(IExtendsRoot, ISecondRoot,))
+        self.assertEqual(impl_extends_root.__bases__,
+                         self._order_for_two(IExtendsRoot, ISecondRoot) + (impl_root,))
+
+
+class Test_classImplementsFirst(Test_classImplements):
+
+    def _callFUT(self, cls, iface):
+        from zope.interface.declarations import classImplementsFirst
+        result = classImplementsFirst(cls, iface) # pylint:disable=assignment-from-no-return
+        self.assertIsNone(result)
+        return cls
+
+    def _order_for_two(self, applied_first, applied_second):
+        return (applied_second, applied_first)
+
+
+class Test__implements_advice(unittest.TestCase):
+
+    def _callFUT(self, *args, **kw):
+        from zope.interface.declarations import _implements_advice
+        return _implements_advice(*args, **kw)
+
+    def test_no_existing_implements(self):
+        from zope.interface.declarations import classImplements
+        from zope.interface.declarations import Implements
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        class Foo(object):
+            __implements_advice_data__ = ((IFoo,), classImplements)
+        self._callFUT(Foo)
+        self.assertNotIn('__implements_advice_data__', Foo.__dict__)
+        self.assertIsInstance(Foo.__implemented__, Implements) # pylint:disable=no-member
+        self.assertEqual(list(Foo.__implemented__), [IFoo]) # pylint:disable=no-member
+
+
+class Test_implementer(Test_classImplements):
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import implementer
+        return implementer
+
+    def _makeOne(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def _callFUT(self, cls, *ifaces):
+        decorator = self._makeOne(*ifaces)
+        return decorator(cls)
+
+    def test_nonclass_cannot_assign_attr(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        decorator = self._makeOne(IFoo)
+        self.assertRaises(TypeError, decorator, object())
+
+    def test_nonclass_can_assign_attr(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        class Foo(object):
+            pass
+        foo = Foo()
+        decorator = self._makeOne(IFoo)
+        returned = decorator(foo)
+        self.assertTrue(returned is foo)
+        spec = foo.__implemented__ # pylint:disable=no-member
+        self.assertEqual(spec.__name__, '__tests__.tests.test_declarations.?')
+        self.assertIsNone(spec.inherit,)
+        self.assertIs(foo.__implemented__, spec) # pylint:disable=no-member
+
+    def test_does_not_leak_on_unique_classes(self):
+        # Make sure nothing is hanging on to the class or Implements
+        # object after they go out of scope. There was briefly a bug
+        # in 5.x that caused SpecificationBase._bases (in C) to not be
+        # traversed or cleared.
+        # https://github.com/zopefoundation/zope.interface/issues/216
+        import gc
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+
+        begin_count = len(gc.get_objects())
+
+        for _ in range(1900):
+            class TestClass(object):
+                pass
+
+            self._callFUT(TestClass, IFoo)
+
+        gc.collect()
+
+        end_count = len(gc.get_objects())
+
+        # How many new objects might still be around? In all currently
+        # tested interpreters, there aren't any, so our counts should
+        # match exactly. When the bug existed, in a steady state, the loop
+        # would grow by two objects each iteration
+        fudge_factor = 0
+        self.assertLessEqual(end_count, begin_count + fudge_factor)
+
+
+
+class Test_implementer_only(Test_classImplementsOnly):
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import implementer_only
+        return implementer_only
+
+    def _makeOne(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def _callFUT(self, cls, iface):
+        decorator = self._makeOne(iface)
+        return decorator(cls)
+
+    def test_function(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        decorator = self._makeOne(IFoo)
+        def _function():
+            raise NotImplementedError()
+        self.assertRaises(ValueError, decorator, _function)
+
+    def test_method(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass('IFoo')
+        decorator = self._makeOne(IFoo)
+        class Bar:
+            def _method(self):
+                raise NotImplementedError()
+        self.assertRaises(ValueError, decorator, Bar._method)
+
+
+
+# Test '_implements' by way of 'implements{,Only}', its only callers.
+
+class Test_implementsOnly(unittest.TestCase, _Py3ClassAdvice):
+
+    def test_simple(self):
+        import warnings
+        from zope.interface.declarations import implementsOnly
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        globs = {'implementsOnly': implementsOnly,
+                 'IFoo': IFoo,
+                }
+        locs = {}
+        CODE = "\n".join([
+            'class Foo(object):'
+            '    implementsOnly(IFoo)',
+            ])
+        with warnings.catch_warnings(record=True) as log:
+            warnings.resetwarnings()
+            try:
+                exec(CODE, globs, locs)  # pylint:disable=exec-used
+            except TypeError:
+                self.assertTrue(PYTHON3, "Must be Python 3")
+            else:
+                if PYTHON3:
+                    self.fail("Didn't raise TypeError")
+                Foo = locs['Foo']
+                spec = Foo.__implemented__
+                self.assertEqual(list(spec), [IFoo])
+                self.assertEqual(len(log), 0) # no longer warn
+
+    def test_called_once_from_class_w_bases(self):
+        from zope.interface.declarations import implements
+        from zope.interface.declarations import implementsOnly
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        IBar = InterfaceClass("IBar")
+        globs = {'implements': implements,
+                 'implementsOnly': implementsOnly,
+                 'IFoo': IFoo,
+                 'IBar': IBar,
+                }
+        locs = {}
+        CODE = "\n".join([
+            'class Foo(object):',
+            '    implements(IFoo)',
+            'class Bar(Foo):'
+            '    implementsOnly(IBar)',
+            ])
+        if self._run_generated_code(CODE, globs, locs):
+            Bar = locs['Bar']
+            spec = Bar.__implemented__
+            self.assertEqual(list(spec), [IBar])
+
+
+class Test_implements(unittest.TestCase, _Py3ClassAdvice):
+
+    def test_called_from_function(self):
+        import warnings
+        from zope.interface.declarations import implements
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        globs = {'implements': implements, 'IFoo': IFoo}
+        locs = {}
+        CODE = "\n".join([
+            'def foo():',
+            '    implements(IFoo)'
+            ])
+        if self._run_generated_code(CODE, globs, locs, False):
+            foo = locs['foo']
+            with warnings.catch_warnings(record=True) as log:
+                warnings.resetwarnings()
+                self.assertRaises(TypeError, foo)
+                self.assertEqual(len(log), 0) # no longer warn
+
+    def test_called_twice_from_class(self):
+        import warnings
+        from zope.interface.declarations import implements
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        IBar = InterfaceClass("IBar")
+        globs = {'implements': implements, 'IFoo': IFoo, 'IBar': IBar}
+        locs = {}
+        CODE = "\n".join([
+            'class Foo(object):',
+            '    implements(IFoo)',
+            '    implements(IBar)',
+            ])
+        with warnings.catch_warnings(record=True) as log:
+            warnings.resetwarnings()
+            try:
+                exec(CODE, globs, locs)  # pylint:disable=exec-used
+            except TypeError:
+                if not PYTHON3:
+                    self.assertEqual(len(log), 0) # no longer warn
+            else:
+                self.fail("Didn't raise TypeError")
+
+    def test_called_once_from_class(self):
+        from zope.interface.declarations import implements
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        globs = {'implements': implements, 'IFoo': IFoo}
+        locs = {}
+        CODE = "\n".join([
+            'class Foo(object):',
+            '    implements(IFoo)',
+            ])
+        if self._run_generated_code(CODE, globs, locs):
+            Foo = locs['Foo']
+            spec = Foo.__implemented__
+            self.assertEqual(list(spec), [IFoo])
+
+
+class ProvidesClassTests(unittest.TestCase):
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import ProvidesClass
+        return ProvidesClass
+
+    def _makeOne(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def test_simple_class_one_interface(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        spec = self._makeOne(Foo, IFoo)
+        self.assertEqual(list(spec), [IFoo])
+
+    def test___reduce__(self):
+        from zope.interface.declarations import Provides # the function
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        spec = self._makeOne(Foo, IFoo)
+        klass, args = spec.__reduce__()
+        self.assertIs(klass, Provides)
+        self.assertEqual(args, (Foo, IFoo))
+
+    def test___get___class(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        spec = self._makeOne(Foo, IFoo)
+        Foo.__provides__ = spec
+        self.assertIs(Foo.__provides__, spec)
+
+    def test___get___instance(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        spec = self._makeOne(Foo, IFoo)
+        Foo.__provides__ = spec
+        def _test():
+            foo = Foo()
+            return foo.__provides__
+        self.assertRaises(AttributeError, _test)
+
+
+class ProvidesClassStrictTests(ProvidesClassTests):
+    # Tests that require the strict C3 resolution order.
+
+    def _getTargetClass(self):
+        ProvidesClass = super(ProvidesClassStrictTests, self)._getTargetClass()
+        class StrictProvides(ProvidesClass):
+            def _do_calculate_ro(self, base_mros):
+                return ProvidesClass._do_calculate_ro(self, base_mros=base_mros, strict=True)
+        return StrictProvides
+
+    def test_overlapping_interfaces_corrected(self):
+        # Giving Provides(cls, IFace), where IFace is already
+        # provided by cls, doesn't produce invalid resolution orders.
+        from zope.interface import implementedBy
+        from zope.interface import Interface
+        from zope.interface import implementer
+
+        class IBase(Interface):
+            pass
+
+        @implementer(IBase)
+        class Base(object):
+            pass
+
+        spec = self._makeOne(Base, IBase)
+        self.assertEqual(spec.__sro__, (
+            spec,
+            implementedBy(Base),
+            IBase,
+            implementedBy(object),
+            Interface
+        ))
+
+
+class TestProvidesClassRepr(unittest.TestCase):
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import ProvidesClass
+        return ProvidesClass
+
+    def _makeOne(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def test__repr__(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        assert IFoo.__name__ == 'IFoo'
+        assert IFoo.__module__ == __name__
+        assert repr(IFoo) == '<InterfaceClass %s.IFoo>' % (__name__,)
+
+        IBar = InterfaceClass("IBar")
+
+        inst = self._makeOne(type(self), IFoo, IBar)
+        self.assertEqual(
+            repr(inst),
+            "directlyProvides(TestProvidesClassRepr, IFoo, IBar)"
+        )
+
+    def test__repr__module_provides_typical_use(self):
+        # as created through a ``moduleProvides()`` statement
+        # in a module body
+        from __tests__.tests import dummy
+        provides = dummy.__provides__ # pylint:disable=no-member
+        self.assertEqual(
+            repr(provides),
+            "directlyProvides(sys.modules['__tests__.tests.dummy'], IDummyModule)"
+        )
+
+    def test__repr__module_after_pickle(self):
+        # It doesn't matter, these objects can't be pickled.
+        import pickle
+        from __tests__.tests import dummy
+        provides = dummy.__provides__ # pylint:disable=no-member
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            with self.assertRaises(pickle.PicklingError):
+                pickle.dumps(provides, proto)
+
+    def test__repr__directlyProvides_module(self):
+        import sys
+        from __tests__.tests import dummy
+        from zope.interface.declarations import directlyProvides
+        from zope.interface.declarations import alsoProvides
+        from zope.interface.interface import InterfaceClass
+
+        IFoo = InterfaceClass('IFoo')
+        IBar = InterfaceClass('IBar')
+
+        orig_provides = dummy.__provides__ # pylint:disable=no-member
+        del dummy.__provides__ # pylint:disable=no-member
+        self.addCleanup(setattr, dummy, '__provides__', orig_provides)
+
+        directlyProvides(dummy, IFoo)
+        provides = dummy.__provides__ # pylint:disable=no-member
+
+        self.assertEqual(
+            repr(provides),
+            "directlyProvides(sys.modules['__tests__.tests.dummy'], IFoo)"
+        )
+
+        alsoProvides(dummy, IBar)
+        provides = dummy.__provides__ # pylint:disable=no-member
+
+        self.assertEqual(
+            repr(provides),
+            "directlyProvides(sys.modules['__tests__.tests.dummy'], IFoo, IBar)"
+        )
+
+        # If we make this module also provide IFoo and IBar, then the repr
+        # lists both names.
+        my_module = sys.modules[__name__]
+        assert not hasattr(my_module, '__provides__')
+
+        directlyProvides(my_module, IFoo, IBar)
+        self.addCleanup(delattr, my_module, '__provides__')
+        self.assertIs(my_module.__provides__, provides)
+        self.assertEqual(
+            repr(provides),
+            "directlyProvides(('__tests__.tests.dummy', "
+            "'__tests__.tests.test_declarations'), "
+            "IFoo, IBar)"
+        )
+
+    def test__repr__module_provides_cached_shared(self):
+        from zope.interface.interface import InterfaceClass
+        from zope.interface.declarations import ModuleType
+        IFoo = InterfaceClass("IFoo")
+
+        inst = self._makeOne(ModuleType, IFoo)
+        inst._v_module_names += ('some.module',)
+        inst._v_module_names += ('another.module',)
+        self.assertEqual(
+            repr(inst),
+            "directlyProvides(('some.module', 'another.module'), IFoo)"
+        )
+
+    def test__repr__duplicate_names(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo", __module__='mod1')
+        IFoo2 = InterfaceClass("IFoo", __module__='mod2')
+        IBaz = InterfaceClass("IBaz")
+
+        inst = self._makeOne(type(self), IFoo, IBaz, IFoo2)
+        self.assertEqual(
+            repr(inst),
+            "directlyProvides(TestProvidesClassRepr, IFoo, IBaz, mod2.IFoo)"
+        )
+
+    def test__repr__implementedBy_in_interfaces(self):
+        from zope.interface import Interface
+        from zope.interface import implementedBy
+        class IFoo(Interface):
+            "Does nothing"
+
+        class Bar(object):
+            "Does nothing"
+
+        impl = implementedBy(type(self))
+
+        inst = self._makeOne(Bar, IFoo, impl)
+        self.assertEqual(
+            repr(inst),
+            'directlyProvides(Bar, IFoo, classImplements(TestProvidesClassRepr))'
+        )
+
+    def test__repr__empty_interfaces(self):
+        inst = self._makeOne(type(self))
+        self.assertEqual(
+            repr(inst),
+            'directlyProvides(TestProvidesClassRepr)',
+        )
+
+    def test__repr__non_class(self):
+        class Object(object):
+            __bases__ = ()
+            __str__ = lambda _: self.fail("Should not call str")
+
+            def __repr__(self):
+                return '<Object>'
+        inst = self._makeOne(Object())
+        self.assertEqual(
+            repr(inst),
+            'directlyProvides(<Object>)',
+        )
+
+    def test__repr__providedBy_from_class(self):
+        from zope.interface.declarations import implementer
+        from zope.interface.declarations import providedBy
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+
+        inst = providedBy(Foo())
+        self.assertEqual(
+            repr(inst),
+            'classImplements(Foo, IFoo)'
+        )
+
+    def test__repr__providedBy_alsoProvides(self):
+        from zope.interface.declarations import implementer
+        from zope.interface.declarations import providedBy
+        from zope.interface.declarations import alsoProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        IBar = InterfaceClass("IBar")
+
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+
+        foo = Foo()
+        alsoProvides(foo, IBar)
+
+        inst = providedBy(foo)
+        self.assertEqual(
+            repr(inst),
+            "directlyProvides(Foo, IBar, classImplements(Foo, IFoo))"
+        )
+
+
+
+class Test_Provides(unittest.TestCase):
+
+    def _callFUT(self, *args, **kw):
+        from zope.interface.declarations import Provides
+        return Provides(*args, **kw)
+
+    def test_no_cached_spec(self):
+        from zope.interface import declarations
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        cache = {}
+        class Foo(object):
+            pass
+        with _Monkey(declarations, InstanceDeclarations=cache):
+            spec = self._callFUT(Foo, IFoo)
+        self.assertEqual(list(spec), [IFoo])
+        self.assertTrue(cache[(Foo, IFoo)] is spec)
+
+    def test_w_cached_spec(self):
+        from zope.interface import declarations
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        prior = object()
+        class Foo(object):
+            pass
+        cache = {(Foo, IFoo): prior}
+        with _Monkey(declarations, InstanceDeclarations=cache):
+            spec = self._callFUT(Foo, IFoo)
+        self.assertTrue(spec is prior)
+
+
+class Test_directlyProvides(unittest.TestCase):
+
+    def _callFUT(self, *args, **kw):
+        from zope.interface.declarations import directlyProvides
+        return directlyProvides(*args, **kw)
+
+    def test_w_normal_object(self):
+        from zope.interface.declarations import ProvidesClass
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        obj = Foo()
+        self._callFUT(obj, IFoo)
+        self.assertIsInstance(obj.__provides__, ProvidesClass) # pylint:disable=no-member
+        self.assertEqual(list(obj.__provides__), [IFoo]) # pylint:disable=no-member
+
+    def test_w_class(self):
+        from zope.interface.declarations import ClassProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        self._callFUT(Foo, IFoo)
+        self.assertIsInstance(Foo.__provides__, ClassProvides) # pylint:disable=no-member
+        self.assertEqual(list(Foo.__provides__), [IFoo]) # pylint:disable=no-member
+
+    @_skip_under_py3k
+    def test_w_non_descriptor_aware_metaclass(self):
+        # There are no non-descriptor-aware types in Py3k
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class MetaClass(type):
+            def __getattribute__(cls, name):
+                # Emulate metaclass whose base is not the type object.
+                if name == '__class__':
+                    return cls
+                # Under certain circumstances, the implementedByFallback
+                # can get here for __dict__
+                return type.__getattribute__(cls, name) # pragma: no cover
+
+        class Foo(object):
+            __metaclass__ = MetaClass
+        obj = Foo()
+        self.assertRaises(TypeError, self._callFUT, obj, IFoo)
+
+    def test_w_classless_object(self):
+        from zope.interface.declarations import ProvidesClass
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        the_dict = {}
+        class Foo(object):
+            def __getattribute__(self, name):
+                # Emulate object w/o any class
+                if name == '__class__':
+                    return None
+                raise NotImplementedError(name)
+            def __setattr__(self, name, value):
+                the_dict[name] = value
+        obj = Foo()
+        self._callFUT(obj, IFoo)
+        self.assertIsInstance(the_dict['__provides__'], ProvidesClass)
+        self.assertEqual(list(the_dict['__provides__']), [IFoo])
+
+
+class Test_alsoProvides(unittest.TestCase):
+
+    def _callFUT(self, *args, **kw):
+        from zope.interface.declarations import alsoProvides
+        return alsoProvides(*args, **kw)
+
+    def test_wo_existing_provides(self):
+        from zope.interface.declarations import ProvidesClass
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        obj = Foo()
+        self._callFUT(obj, IFoo)
+        self.assertIsInstance(obj.__provides__, ProvidesClass) # pylint:disable=no-member
+        self.assertEqual(list(obj.__provides__), [IFoo]) # pylint:disable=no-member
+
+    def test_w_existing_provides(self):
+        from zope.interface.declarations import directlyProvides
+        from zope.interface.declarations import ProvidesClass
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        IBar = InterfaceClass("IBar")
+        class Foo(object):
+            pass
+        obj = Foo()
+        directlyProvides(obj, IFoo)
+        self._callFUT(obj, IBar)
+        self.assertIsInstance(obj.__provides__, ProvidesClass) # pylint:disable=no-member
+        self.assertEqual(list(obj.__provides__), [IFoo, IBar]) # pylint:disable=no-member
+
+
+class Test_noLongerProvides(unittest.TestCase):
+
+    def _callFUT(self, *args, **kw):
+        from zope.interface.declarations import noLongerProvides
+        return noLongerProvides(*args, **kw)
+
+    def test_wo_existing_provides(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        obj = Foo()
+        self._callFUT(obj, IFoo)
+        self.assertEqual(list(obj.__provides__), []) # pylint:disable=no-member
+
+    def test_w_existing_provides_hit(self):
+        from zope.interface.declarations import directlyProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        obj = Foo()
+        directlyProvides(obj, IFoo)
+        self._callFUT(obj, IFoo)
+        self.assertEqual(list(obj.__provides__), []) # pylint:disable=no-member
+
+    def test_w_existing_provides_miss(self):
+        from zope.interface.declarations import directlyProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        IBar = InterfaceClass("IBar")
+        class Foo(object):
+            pass
+        obj = Foo()
+        directlyProvides(obj, IFoo)
+        self._callFUT(obj, IBar)
+        self.assertEqual(list(obj.__provides__), [IFoo]) # pylint:disable=no-member
+
+    def test_w_iface_implemented_by_class(self):
+        from zope.interface.declarations import implementer
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+        obj = Foo()
+        self.assertRaises(ValueError, self._callFUT, obj, IFoo)
+
+
+class ClassProvidesBaseFallbackTests(unittest.TestCase):
+
+    def _getTargetClass(self):
+        # pylint:disable=no-name-in-module
+        from zope.interface.declarations import ClassProvidesBaseFallback
+        return ClassProvidesBaseFallback
+
+    def _makeOne(self, klass, implements):
+        # Don't instantiate directly:  the C version can't have attributes
+        # assigned.
+        class Derived(self._getTargetClass()):
+            def __init__(self, k, i):
+                self._cls = k
+                self._implements = i
+        return Derived(klass, implements)
+
+    def test_w_same_class_via_class(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        cpbp = Foo.__provides__ = self._makeOne(Foo, IFoo)
+        self.assertTrue(Foo.__provides__ is cpbp)
+
+    def test_w_same_class_via_instance(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        foo = Foo()
+        Foo.__provides__ = self._makeOne(Foo, IFoo)
+        self.assertIs(foo.__provides__, IFoo)
+
+    def test_w_different_class(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        class Bar(Foo):
+            pass
+        bar = Bar()
+        Foo.__provides__ = self._makeOne(Foo, IFoo)
+        self.assertRaises(AttributeError, getattr, Bar, '__provides__')
+        self.assertRaises(AttributeError, getattr, bar, '__provides__')
+
+
+class ClassProvidesBaseTests(OptimizationTestMixin,
+                             ClassProvidesBaseFallbackTests):
+    # Repeat tests for C optimizations
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import ClassProvidesBase
+        return ClassProvidesBase
+
+    def _getFallbackClass(self):
+        # pylint:disable=no-name-in-module
+        from zope.interface.declarations import ClassProvidesBaseFallback
+        return ClassProvidesBaseFallback
+
+
+class ClassProvidesTests(unittest.TestCase):
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import ClassProvides
+        return ClassProvides
+
+    def _makeOne(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def test_w_simple_metaclass(self):
+        from zope.interface.declarations import implementer
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        IBar = InterfaceClass("IBar")
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+        cp = Foo.__provides__ = self._makeOne(Foo, type(Foo), IBar)
+        self.assertTrue(Foo.__provides__ is cp)
+        self.assertEqual(list(Foo().__provides__), [IFoo])
+
+    def test___reduce__(self):
+        from zope.interface.declarations import implementer
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        IBar = InterfaceClass("IBar")
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+        cp = Foo.__provides__ = self._makeOne(Foo, type(Foo), IBar)
+        self.assertEqual(cp.__reduce__(),
+                         (type(cp), (Foo, type(Foo), IBar)))
+
+
+class ClassProvidesStrictTests(ClassProvidesTests):
+    # Tests that require the strict C3 resolution order.
+
+    def _getTargetClass(self):
+        ClassProvides = super(ClassProvidesStrictTests, self)._getTargetClass()
+        class StrictClassProvides(ClassProvides):
+            def _do_calculate_ro(self, base_mros):
+                return ClassProvides._do_calculate_ro(self, base_mros=base_mros, strict=True)
+        return StrictClassProvides
+
+    def test_overlapping_interfaces_corrected(self):
+        # Giving ClassProvides(cls, metaclass, IFace), where IFace is already
+        # provided by metacls, doesn't produce invalid resolution orders.
+        from zope.interface import implementedBy
+        from zope.interface import Interface
+        from zope.interface import implementer
+
+        class IBase(Interface):
+            pass
+
+        @implementer(IBase)
+        class metaclass(type):
+            pass
+
+        cls = metaclass(
+            'cls',
+            (object,),
+            {}
+        )
+
+        spec = self._makeOne(cls, metaclass, IBase)
+        self.assertEqual(spec.__sro__, (
+            spec,
+            implementedBy(metaclass),
+            IBase,
+            implementedBy(type),
+            implementedBy(object),
+            Interface
+        ))
+
+
+class TestClassProvidesRepr(unittest.TestCase):
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import ClassProvides
+        return ClassProvides
+
+    def _makeOne(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def test__repr__empty(self):
+        inst = self._makeOne(type(self), type)
+        self.assertEqual(
+            repr(inst),
+            "directlyProvides(TestClassProvidesRepr)"
+        )
+
+    def test__repr__providing_one(self):
+        from zope.interface import Interface
+        class IFoo(Interface):
+            "Does nothing"
+
+        inst = self._makeOne(type(self), type, IFoo)
+        self.assertEqual(
+            repr(inst),
+            "directlyProvides(TestClassProvidesRepr, IFoo)"
+        )
+
+    def test__repr__duplicate_names(self):
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo", __module__='mod1')
+        IFoo2 = InterfaceClass("IFoo", __module__='mod2')
+        IBaz = InterfaceClass("IBaz")
+
+        inst = self._makeOne(type(self), type, IFoo, IBaz, IFoo2)
+        self.assertEqual(
+            repr(inst),
+            "directlyProvides(TestClassProvidesRepr, IFoo, IBaz, mod2.IFoo)"
+        )
+
+    def test__repr__implementedBy(self):
+        from zope.interface.declarations import implementer
+        from zope.interface.declarations import implementedBy
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+
+        inst = implementedBy(Foo)
+        self.assertEqual(
+            repr(inst),
+            'classImplements(Foo, IFoo)'
+        )
+
+    def test__repr__implementedBy_generic_callable(self):
+        from zope.interface.declarations import implementedBy
+        # We can't get a __name__ by default, so we get a
+        # module name and a question mark
+        class Callable(object):
+            def __call__(self):
+                return self
+
+        inst = implementedBy(Callable())
+        self.assertEqual(
+            repr(inst),
+            'classImplements(%s.?)' % (__name__,)
+        )
+
+        c = Callable()
+        c.__name__ = 'Callable'
+        inst = implementedBy(c)
+        self.assertEqual(
+            repr(inst),
+            'classImplements(Callable)'
+        )
+
+
+class Test_directlyProvidedBy(unittest.TestCase):
+
+    def _callFUT(self, *args, **kw):
+        from zope.interface.declarations import directlyProvidedBy
+        return directlyProvidedBy(*args, **kw)
+
+    def test_wo_declarations_in_class_or_instance(self):
+        class Foo(object):
+            pass
+        foo = Foo()
+        self.assertEqual(list(self._callFUT(foo)), [])
+
+    def test_w_declarations_in_class_but_not_instance(self):
+        from zope.interface.declarations import implementer
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+        foo = Foo()
+        self.assertEqual(list(self._callFUT(foo)), [])
+
+    def test_w_declarations_in_instance_but_not_class(self):
+        from zope.interface.declarations import directlyProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        foo = Foo()
+        directlyProvides(foo, IFoo)
+        self.assertEqual(list(self._callFUT(foo)), [IFoo])
+
+    def test_w_declarations_in_instance_and_class(self):
+        from zope.interface.declarations import directlyProvides
+        from zope.interface.declarations import implementer
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        IBar = InterfaceClass("IBar")
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+        foo = Foo()
+        directlyProvides(foo, IBar)
+        self.assertEqual(list(self._callFUT(foo)), [IBar])
+
+
+class Test_classProvides(unittest.TestCase, _Py3ClassAdvice):
+    # pylint:disable=exec-used
+
+    def test_called_from_function(self):
+        import warnings
+        from zope.interface.declarations import classProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        globs = {'classProvides': classProvides, 'IFoo': IFoo}
+        locs = {}
+        CODE = "\n".join([
+            'def foo():',
+            '    classProvides(IFoo)'
+            ])
+        exec(CODE, globs, locs)
+        foo = locs['foo']
+        with warnings.catch_warnings(record=True) as log:
+            warnings.resetwarnings()
+            self.assertRaises(TypeError, foo)
+            if not PYTHON3:
+                self.assertEqual(len(log), 0) # no longer warn
+
+    def test_called_twice_from_class(self):
+        import warnings
+        from zope.interface.declarations import classProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        IBar = InterfaceClass("IBar")
+        globs = {'classProvides': classProvides, 'IFoo': IFoo, 'IBar': IBar}
+        locs = {}
+        CODE = "\n".join([
+            'class Foo(object):',
+            '    classProvides(IFoo)',
+            '    classProvides(IBar)',
+            ])
+        with warnings.catch_warnings(record=True) as log:
+            warnings.resetwarnings()
+            try:
+                exec(CODE, globs, locs)
+            except TypeError:
+                if not PYTHON3:
+                    self.assertEqual(len(log), 0) # no longer warn
+            else:
+                self.fail("Didn't raise TypeError")
+
+    def test_called_once_from_class(self):
+        from zope.interface.declarations import classProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        globs = {'classProvides': classProvides, 'IFoo': IFoo}
+        locs = {}
+        CODE = "\n".join([
+            'class Foo(object):',
+            '    classProvides(IFoo)',
+            ])
+        if self._run_generated_code(CODE, globs, locs):
+            Foo = locs['Foo']
+            spec = Foo.__providedBy__
+            self.assertEqual(list(spec), [IFoo])
+
+# Test _classProvides_advice through classProvides, its only caller.
+
+
+class Test_provider(unittest.TestCase):
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import provider
+        return provider
+
+    def _makeOne(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def test_w_class(self):
+        from zope.interface.declarations import ClassProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        @self._makeOne(IFoo)
+        class Foo(object):
+            pass
+        self.assertIsInstance(Foo.__provides__, ClassProvides) # pylint:disable=no-member
+        self.assertEqual(list(Foo.__provides__), [IFoo]) # pylint:disable=no-member
+
+
+class Test_moduleProvides(unittest.TestCase):
+    # pylint:disable=exec-used
+
+    def test_called_from_function(self):
+        from zope.interface.declarations import moduleProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        globs = {'__name__': '__tests__.tests.tests.foo',
+                 'moduleProvides': moduleProvides, 'IFoo': IFoo}
+        locs = {}
+        CODE = "\n".join([
+            'def foo():',
+            '    moduleProvides(IFoo)'
+            ])
+        exec(CODE, globs, locs)
+        foo = locs['foo']
+        self.assertRaises(TypeError, foo)
+
+    def test_called_from_class(self):
+        from zope.interface.declarations import moduleProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        globs = {'__name__': '__tests__.tests.tests.foo',
+                 'moduleProvides': moduleProvides, 'IFoo': IFoo}
+        locs = {}
+        CODE = "\n".join([
+            'class Foo(object):',
+            '    moduleProvides(IFoo)',
+            ])
+        with self.assertRaises(TypeError):
+            exec(CODE, globs, locs)
+
+    def test_called_once_from_module_scope(self):
+        from zope.interface.declarations import moduleProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        globs = {'__name__': '__tests__.tests.tests.foo',
+                 'moduleProvides': moduleProvides, 'IFoo': IFoo}
+        CODE = "\n".join([
+            'moduleProvides(IFoo)',
+            ])
+        exec(CODE, globs)
+        spec = globs['__provides__']
+        self.assertEqual(list(spec), [IFoo])
+
+    def test_called_twice_from_module_scope(self):
+        from zope.interface.declarations import moduleProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        globs = {'__name__': '__tests__.tests.tests.foo',
+                 'moduleProvides': moduleProvides, 'IFoo': IFoo}
+
+        CODE = "\n".join([
+            'moduleProvides(IFoo)',
+            'moduleProvides(IFoo)',
+            ])
+        with self.assertRaises(TypeError):
+            exec(CODE, globs)
+
+
+class Test_getObjectSpecificationFallback(unittest.TestCase):
+
+    def _getFallbackClass(self):
+        # pylint:disable=no-name-in-module
+        from zope.interface.declarations import getObjectSpecificationFallback
+        return getObjectSpecificationFallback
+
+    _getTargetClass = _getFallbackClass
+
+    def _callFUT(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def test_wo_existing_provides_classless(self):
+        the_dict = {}
+        class Foo(object):
+            def __getattribute__(self, name):
+                # Emulate object w/o any class
+                if name == '__class__':
+                    raise AttributeError(name)
+                try:
+                    return the_dict[name]
+                except KeyError:
+                    raise AttributeError(name)
+            def __setattr__(self, name, value):
+                raise NotImplementedError()
+        foo = Foo()
+        spec = self._callFUT(foo)
+        self.assertEqual(list(spec), [])
+
+    def test_existing_provides_is_spec(self):
+        from zope.interface.declarations import directlyProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        def foo():
+            raise NotImplementedError()
+        directlyProvides(foo, IFoo)
+        spec = self._callFUT(foo)
+        self.assertIs(spec, foo.__provides__) # pylint:disable=no-member
+
+    def test_existing_provides_is_not_spec(self):
+        def foo():
+            raise NotImplementedError()
+        foo.__provides__ = object() # not a valid spec
+        spec = self._callFUT(foo)
+        self.assertEqual(list(spec), [])
+
+    def test_existing_provides(self):
+        from zope.interface.declarations import directlyProvides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        foo = Foo()
+        directlyProvides(foo, IFoo)
+        spec = self._callFUT(foo)
+        self.assertEqual(list(spec), [IFoo])
+
+    def test_wo_provides_on_class_w_implements(self):
+        from zope.interface.declarations import implementer
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+        foo = Foo()
+        spec = self._callFUT(foo)
+        self.assertEqual(list(spec), [IFoo])
+
+    def test_wo_provides_on_class_wo_implements(self):
+        class Foo(object):
+            pass
+        foo = Foo()
+        spec = self._callFUT(foo)
+        self.assertEqual(list(spec), [])
+
+    def test_catches_only_AttributeError_on_provides(self):
+        MissingSomeAttrs.test_raises(self, self._callFUT, expected_missing='__provides__')
+
+    def test_catches_only_AttributeError_on_class(self):
+        MissingSomeAttrs.test_raises(self, self._callFUT, expected_missing='__class__',
+                                     __provides__=None)
+
+    def test_raises_AttributeError_when_provides_fails_type_check_AttributeError(self):
+        # isinstance(ob.__provides__, SpecificationBase) is not
+        # protected inside any kind of block.
+
+        class Foo(object):
+            __provides__ = MissingSomeAttrs(AttributeError)
+
+        # isinstance() ignores AttributeError on __class__
+        self._callFUT(Foo())
+
+    def test_raises_AttributeError_when_provides_fails_type_check_RuntimeError(self):
+        # isinstance(ob.__provides__, SpecificationBase) is not
+        # protected inside any kind of block.
+        class Foo(object):
+            __provides__ = MissingSomeAttrs(RuntimeError)
+
+        if PYTHON3:
+            with self.assertRaises(RuntimeError) as exc:
+                self._callFUT(Foo())
+
+            self.assertEqual('__class__', exc.exception.args[0])
+        else:
+            # Python 2 catches everything.
+            self._callFUT(Foo())
+
+
+class Test_getObjectSpecification(Test_getObjectSpecificationFallback,
+                                  OptimizationTestMixin):
+    # Repeat tests for C optimizations
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import getObjectSpecification
+        return getObjectSpecification
+
+
+class Test_providedByFallback(unittest.TestCase):
+
+    def _getFallbackClass(self):
+        # pylint:disable=no-name-in-module
+        from zope.interface.declarations import providedByFallback
+        return providedByFallback
+
+    _getTargetClass = _getFallbackClass
+
+    def _callFUT(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def test_wo_providedBy_on_class_wo_implements(self):
+        class Foo(object):
+            pass
+        foo = Foo()
+        spec = self._callFUT(foo)
+        self.assertEqual(list(spec), [])
+
+    def test_w_providedBy_valid_spec(self):
+        from zope.interface.declarations import Provides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        foo = Foo()
+        foo.__providedBy__ = Provides(Foo, IFoo)
+        spec = self._callFUT(foo)
+        self.assertEqual(list(spec), [IFoo])
+
+    def test_w_providedBy_invalid_spec(self):
+        class Foo(object):
+            pass
+        foo = Foo()
+        foo.__providedBy__ = object()
+        spec = self._callFUT(foo)
+        self.assertEqual(list(spec), [])
+
+    def test_w_providedBy_invalid_spec_class_w_implements(self):
+        from zope.interface.declarations import implementer
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+        foo = Foo()
+        foo.__providedBy__ = object()
+        spec = self._callFUT(foo)
+        self.assertEqual(list(spec), [IFoo])
+
+    def test_w_providedBy_invalid_spec_w_provides_no_provides_on_class(self):
+        class Foo(object):
+            pass
+        foo = Foo()
+        foo.__providedBy__ = object()
+        expected = foo.__provides__ = object()
+        spec = self._callFUT(foo)
+        self.assertTrue(spec is expected)
+
+    def test_w_providedBy_invalid_spec_w_provides_diff_provides_on_class(self):
+        class Foo(object):
+            pass
+        foo = Foo()
+        foo.__providedBy__ = object()
+        expected = foo.__provides__ = object()
+        Foo.__provides__ = object()
+        spec = self._callFUT(foo)
+        self.assertTrue(spec is expected)
+
+    def test_w_providedBy_invalid_spec_w_provides_same_provides_on_class(self):
+        from zope.interface.declarations import implementer
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+        foo = Foo()
+        foo.__providedBy__ = object()
+        foo.__provides__ = Foo.__provides__ = object()
+        spec = self._callFUT(foo)
+        self.assertEqual(list(spec), [IFoo])
+
+    def test_super_when_base_implements_interface(self):
+        from zope.interface import Interface
+        from zope.interface.declarations import implementer
+
+        class IBase(Interface):
+            pass
+
+        class IDerived(IBase):
+            pass
+
+        @implementer(IBase)
+        class Base(object):
+            pass
+
+        @implementer(IDerived)
+        class Derived(Base):
+            pass
+
+        derived = Derived()
+        self.assertEqual(list(self._callFUT(derived)), [IDerived, IBase])
+
+        sup = super(Derived, derived)
+        fut = self._callFUT(sup)
+        self.assertIsNone(fut._dependents)
+        self.assertEqual(list(fut), [IBase])
+
+    def test_super_when_base_doesnt_implement_interface(self):
+        from zope.interface import Interface
+        from zope.interface.declarations import implementer
+
+        class IBase(Interface):
+            pass
+
+        class IDerived(IBase):
+            pass
+
+        class Base(object):
+            pass
+
+        @implementer(IDerived)
+        class Derived(Base):
+            pass
+
+        derived = Derived()
+        self.assertEqual(list(self._callFUT(derived)), [IDerived])
+
+        sup = super(Derived, derived)
+        self.assertEqual(list(self._callFUT(sup)), [])
+
+    def test_super_when_base_is_object(self):
+        from zope.interface import Interface
+        from zope.interface.declarations import implementer
+
+        class IBase(Interface):
+            pass
+
+        class IDerived(IBase):
+            pass
+
+        @implementer(IDerived)
+        class Derived(object):
+            pass
+
+        derived = Derived()
+        self.assertEqual(list(self._callFUT(derived)), [IDerived])
+
+        sup = super(Derived, derived)
+        fut = self._callFUT(sup)
+        self.assertIsNone(fut._dependents)
+        self.assertEqual(list(fut), [])
+
+    def test_super_when_object_directly_provides(self):
+        from zope.interface import Interface
+        from zope.interface.declarations import implementer
+        from zope.interface.declarations import directlyProvides
+
+        class IBase(Interface):
+            pass
+
+        class IDerived(IBase):
+            pass
+
+        @implementer(IBase)
+        class Base(object):
+            pass
+
+        class Derived(Base):
+            pass
+
+        derived = Derived()
+        self.assertEqual(list(self._callFUT(derived)), [IBase])
+
+        directlyProvides(derived, IDerived)
+        self.assertEqual(list(self._callFUT(derived)), [IDerived, IBase])
+
+        sup = super(Derived, derived)
+        fut = self._callFUT(sup)
+        self.assertIsNone(fut._dependents)
+        self.assertEqual(list(fut), [IBase])
+
+    def test_super_multi_level_multi_inheritance(self):
+        from zope.interface.declarations import implementer
+        from zope.interface import Interface
+
+        class IBase(Interface):
+            pass
+
+        class IM1(Interface):
+            pass
+
+        class IM2(Interface):
+            pass
+
+        class IDerived(IBase):
+            pass
+
+        class IUnrelated(Interface):
+            pass
+
+        @implementer(IBase)
+        class Base(object):
+            pass
+
+        @implementer(IM1)
+        class M1(Base):
+            pass
+
+        @implementer(IM2)
+        class M2(Base):
+            pass
+
+        @implementer(IDerived, IUnrelated)
+        class Derived(M1, M2):
+            pass
+
+        d = Derived()
+        sd = super(Derived, d)
+        sm1 = super(M1, d)
+        sm2 = super(M2, d)
+
+        self.assertEqual(list(self._callFUT(d)),
+                         [IDerived, IUnrelated, IM1, IBase, IM2])
+        self.assertEqual(list(self._callFUT(sd)),
+                         [IM1, IBase, IM2])
+        self.assertEqual(list(self._callFUT(sm1)),
+                         [IM2, IBase])
+        self.assertEqual(list(self._callFUT(sm2)),
+                         [IBase])
+
+    def test_catches_only_AttributeError_on_providedBy(self):
+        MissingSomeAttrs.test_raises(self, self._callFUT,
+                                     expected_missing='__providedBy__',
+                                     __class__=object)
+
+    def test_catches_only_AttributeError_on_class(self):
+        # isinstance() tries to get the __class__, which is non-obvious,
+        # so it must be protected too.
+        PY3 = str is not bytes
+        MissingSomeAttrs.test_raises(self, self._callFUT,
+                                     expected_missing='__class__' if PY3 else '__providedBy__')
+
+
+
+class Test_providedBy(Test_providedByFallback,
+                      OptimizationTestMixin):
+    # Repeat tests for C optimizations
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import providedBy
+        return providedBy
+
+
+class ObjectSpecificationDescriptorFallbackTests(unittest.TestCase):
+
+    def _getFallbackClass(self):
+        # pylint:disable=no-name-in-module
+        from zope.interface.declarations \
+            import ObjectSpecificationDescriptorFallback
+        return ObjectSpecificationDescriptorFallback
+
+    _getTargetClass = _getFallbackClass
+
+    def _makeOne(self, *args, **kw):
+        return self._getTargetClass()(*args, **kw)
+
+    def test_accessed_via_class(self):
+        from zope.interface.declarations import Provides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        class Foo(object):
+            pass
+        Foo.__provides__ = Provides(Foo, IFoo)
+        Foo.__providedBy__ = self._makeOne()
+        self.assertEqual(list(Foo.__providedBy__), [IFoo])
+
+    def test_accessed_via_inst_wo_provides(self):
+        from zope.interface.declarations import implementer
+        from zope.interface.declarations import Provides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        IBar = InterfaceClass("IBar")
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+        Foo.__provides__ = Provides(Foo, IBar)
+        Foo.__providedBy__ = self._makeOne()
+        foo = Foo()
+        self.assertEqual(list(foo.__providedBy__), [IFoo])
+
+    def test_accessed_via_inst_w_provides(self):
+        from zope.interface.declarations import directlyProvides
+        from zope.interface.declarations import implementer
+        from zope.interface.declarations import Provides
+        from zope.interface.interface import InterfaceClass
+        IFoo = InterfaceClass("IFoo")
+        IBar = InterfaceClass("IBar")
+        IBaz = InterfaceClass("IBaz")
+        @implementer(IFoo)
+        class Foo(object):
+            pass
+        Foo.__provides__ = Provides(Foo, IBar)
+        Foo.__providedBy__ = self._makeOne()
+        foo = Foo()
+        directlyProvides(foo, IBaz)
+        self.assertEqual(list(foo.__providedBy__), [IBaz, IFoo])
+
+    def test_arbitrary_exception_accessing_provides_not_caught(self):
+
+        class MyException(Exception):
+            pass
+
+        class Foo(object):
+            __providedBy__ = self._makeOne()
+
+            @property
+            def __provides__(self):
+                raise MyException
+
+        foo = Foo()
+        with self.assertRaises(MyException):
+            getattr(foo, '__providedBy__')
+
+    def test_AttributeError_accessing_provides_caught(self):
+
+        class MyException(Exception):
+            pass
+
+        class Foo(object):
+            __providedBy__ = self._makeOne()
+
+            @property
+            def __provides__(self):
+                raise AttributeError
+
+        foo = Foo()
+        provided = getattr(foo, '__providedBy__')
+        self.assertIsNotNone(provided)
+
+    def test_None_in__provides__overrides(self):
+        from zope.interface import Interface
+        from zope.interface import implementer
+
+        class IFoo(Interface):
+            pass
+
+        @implementer(IFoo)
+        class Foo(object):
+
+            @property
+            def __provides__(self):
+                return None
+
+        Foo.__providedBy__ = self._makeOne()
+
+        provided = getattr(Foo(), '__providedBy__')
+        self.assertIsNone(provided)
+
+class ObjectSpecificationDescriptorTests(
+        ObjectSpecificationDescriptorFallbackTests,
+        OptimizationTestMixin):
+    # Repeat tests for C optimizations
+
+    def _getTargetClass(self):
+        from zope.interface.declarations import ObjectSpecificationDescriptor
+        return ObjectSpecificationDescriptor
+
+
+# Test _normalizeargs through its callers.
+
+
+class _Monkey(object):
+    # context-manager for replacing module names in the scope of a test.
+    def __init__(self, module, **kw):
+        self.module = module
+        self.to_restore = {key: getattr(module, key) for key in kw}
+        for key, value in kw.items():
+            setattr(module, key, value)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        for key, value in self.to_restore.items():
+            setattr(self.module, key, value)
+
+
+class _MonkeyDict(object):
+    # context-manager for restoring a dict w/in a module in the scope of a test.
+    def __init__(self, module, attrname, **kw):
+        self.module = module
+        self.target = getattr(module, attrname)
+        self.to_restore = self.target.copy()
+        self.target.clear()
+        self.target.update(kw)
+
+    def __enter__(self):
+        return self.target
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.target.clear()
+        self.target.update(self.to_restore)