diff --git a/Lib/test/mapping_tests.py b/Lib/test/mapping_tests.py
new file mode 100644
index 000000000..53f29f605
--- /dev/null
+++ b/Lib/test/mapping_tests.py
@@ -0,0 +1,666 @@
+# tests common to dict and UserDict
+import unittest
+import collections
+import sys
+
+
+class BasicTestMappingProtocol(unittest.TestCase):
+    # This base class can be used to check that an object conforms to the
+    # mapping protocol
+
+    # Functions that can be useful to override to adapt to dictionary
+    # semantics
+    type2test = None # which class is being tested (overwrite in subclasses)
+
+    def _reference(self):
+        """Return a dictionary of values which are invariant by storage
+        in the object under test."""
+        return {"1": "2", "key1":"value1", "key2":(1,2,3)}
+    def _empty_mapping(self):
+        """Return an empty mapping object"""
+        return self.type2test()
+    def _full_mapping(self, data):
+        """Return a mapping object with the value contained in data
+        dictionary"""
+        x = self._empty_mapping()
+        for key, value in data.items():
+            x[key] = value
+        return x
+
+    def __init__(self, *args, **kw):
+        unittest.TestCase.__init__(self, *args, **kw)
+        self.reference = self._reference().copy()
+
+        # A (key, value) pair not in the mapping
+        key, value = self.reference.popitem()
+        self.other = {key:value}
+
+        # A (key, value) pair in the mapping
+        key, value = self.reference.popitem()
+        self.inmapping = {key:value}
+        self.reference[key] = value
+
+    def test_read(self):
+        # Test for read only operations on mapping
+        p = self._empty_mapping()
+        p1 = dict(p) #workaround for singleton objects
+        d = self._full_mapping(self.reference)
+        if d is p:
+            p = p1
+        #Indexing
+        for key, value in self.reference.items():
+            self.assertEqual(d[key], value)
+        knownkey = list(self.other.keys())[0]
+        self.assertRaises(KeyError, lambda:d[knownkey])
+        #len
+        self.assertEqual(len(p), 0)
+        self.assertEqual(len(d), len(self.reference))
+        #__contains__
+        for k in self.reference:
+            self.assertIn(k, d)
+        for k in self.other:
+            self.assertNotIn(k, d)
+        #cmp
+        self.assertEqual(p, p)
+        self.assertEqual(d, d)
+        self.assertNotEqual(p, d)
+        self.assertNotEqual(d, p)
+        #bool
+        if p: self.fail("Empty mapping must compare to False")
+        if not d: self.fail("Full mapping must compare to True")
+        # keys(), items(), iterkeys() ...
+        def check_iterandlist(iter, lst, ref):
+            self.assertTrue(hasattr(iter, '__next__'))
+            self.assertTrue(hasattr(iter, '__iter__'))
+            x = list(iter)
+            self.assertTrue(set(x)==set(lst)==set(ref))
+        check_iterandlist(iter(d.keys()), list(d.keys()),
+                          self.reference.keys())
+        check_iterandlist(iter(d), list(d.keys()), self.reference.keys())
+        check_iterandlist(iter(d.values()), list(d.values()),
+                          self.reference.values())
+        check_iterandlist(iter(d.items()), list(d.items()),
+                          self.reference.items())
+        #get
+        key, value = next(iter(d.items()))
+        knownkey, knownvalue = next(iter(self.other.items()))
+        self.assertEqual(d.get(key, knownvalue), value)
+        self.assertEqual(d.get(knownkey, knownvalue), knownvalue)
+        self.assertNotIn(knownkey, d)
+
+    def test_write(self):
+        # Test for write operations on mapping
+        p = self._empty_mapping()
+        #Indexing
+        for key, value in self.reference.items():
+            p[key] = value
+            self.assertEqual(p[key], value)
+        for key in self.reference.keys():
+            del p[key]
+            self.assertRaises(KeyError, lambda:p[key])
+        p = self._empty_mapping()
+        #update
+        p.update(self.reference)
+        self.assertEqual(dict(p), self.reference)
+        items = list(p.items())
+        p = self._empty_mapping()
+        p.update(items)
+        self.assertEqual(dict(p), self.reference)
+        d = self._full_mapping(self.reference)
+        #setdefault
+        key, value = next(iter(d.items()))
+        knownkey, knownvalue = next(iter(self.other.items()))
+        self.assertEqual(d.setdefault(key, knownvalue), value)
+        self.assertEqual(d[key], value)
+        self.assertEqual(d.setdefault(knownkey, knownvalue), knownvalue)
+        self.assertEqual(d[knownkey], knownvalue)
+        #pop
+        self.assertEqual(d.pop(knownkey), knownvalue)
+        self.assertNotIn(knownkey, d)
+        self.assertRaises(KeyError, d.pop, knownkey)
+        default = 909
+        d[knownkey] = knownvalue
+        self.assertEqual(d.pop(knownkey, default), knownvalue)
+        self.assertNotIn(knownkey, d)
+        self.assertEqual(d.pop(knownkey, default), default)
+        #popitem
+        key, value = d.popitem()
+        self.assertNotIn(key, d)
+        self.assertEqual(value, self.reference[key])
+        p=self._empty_mapping()
+        self.assertRaises(KeyError, p.popitem)
+
+    def test_constructor(self):
+        self.assertEqual(self._empty_mapping(), self._empty_mapping())
+
+    def test_bool(self):
+        self.assertTrue(not self._empty_mapping())
+        self.assertTrue(self.reference)
+        self.assertTrue(bool(self._empty_mapping()) is False)
+        self.assertTrue(bool(self.reference) is True)
+
+    def test_keys(self):
+        d = self._empty_mapping()
+        self.assertEqual(list(d.keys()), [])
+        d = self.reference
+        self.assertIn(list(self.inmapping.keys())[0], d.keys())
+        self.assertNotIn(list(self.other.keys())[0], d.keys())
+        self.assertRaises(TypeError, d.keys, None)
+
+    def test_values(self):
+        d = self._empty_mapping()
+        self.assertEqual(list(d.values()), [])
+
+        self.assertRaises(TypeError, d.values, None)
+
+    def test_items(self):
+        d = self._empty_mapping()
+        self.assertEqual(list(d.items()), [])
+
+        self.assertRaises(TypeError, d.items, None)
+
+    def test_len(self):
+        d = self._empty_mapping()
+        self.assertEqual(len(d), 0)
+
+    def test_getitem(self):
+        d = self.reference
+        self.assertEqual(d[list(self.inmapping.keys())[0]],
+                         list(self.inmapping.values())[0])
+
+        self.assertRaises(TypeError, d.__getitem__)
+
+    def test_update(self):
+        # mapping argument
+        d = self._empty_mapping()
+        d.update(self.other)
+        self.assertEqual(list(d.items()), list(self.other.items()))
+
+        # No argument
+        d = self._empty_mapping()
+        d.update()
+        self.assertEqual(d, self._empty_mapping())
+
+        # item sequence
+        d = self._empty_mapping()
+        d.update(self.other.items())
+        self.assertEqual(list(d.items()), list(self.other.items()))
+
+        # Iterator
+        d = self._empty_mapping()
+        d.update(self.other.items())
+        self.assertEqual(list(d.items()), list(self.other.items()))
+
+        # FIXME: Doesn't work with UserDict
+        # self.assertRaises((TypeError, AttributeError), d.update, None)
+        self.assertRaises((TypeError, AttributeError), d.update, 42)
+
+        outerself = self
+        class SimpleUserDict:
+            def __init__(self):
+                self.d = outerself.reference
+            def keys(self):
+                return self.d.keys()
+            def __getitem__(self, i):
+                return self.d[i]
+        d.clear()
+        d.update(SimpleUserDict())
+        i1 = sorted(d.items())
+        i2 = sorted(self.reference.items())
+        self.assertEqual(i1, i2)
+
+        class Exc(Exception): pass
+
+        d = self._empty_mapping()
+        class FailingUserDict:
+            def keys(self):
+                raise Exc
+        self.assertRaises(Exc, d.update, FailingUserDict())
+
+        d.clear()
+
+        class FailingUserDict:
+            def keys(self):
+                class BogonIter:
+                    def __init__(self):
+                        self.i = 1
+                    def __iter__(self):
+                        return self
+                    def __next__(self):
+                        if self.i:
+                            self.i = 0
+                            return 'a'
+                        raise Exc
+                return BogonIter()
+            def __getitem__(self, key):
+                return key
+        self.assertRaises(Exc, d.update, FailingUserDict())
+
+        class FailingUserDict:
+            def keys(self):
+                class BogonIter:
+                    def __init__(self):
+                        self.i = ord('a')
+                    def __iter__(self):
+                        return self
+                    def __next__(self):
+                        if self.i <= ord('z'):
+                            rtn = chr(self.i)
+                            self.i += 1
+                            return rtn
+                        raise StopIteration
+                return BogonIter()
+            def __getitem__(self, key):
+                raise Exc
+        self.assertRaises(Exc, d.update, FailingUserDict())
+
+        d = self._empty_mapping()
+        class badseq(object):
+            def __iter__(self):
+                return self
+            def __next__(self):
+                raise Exc()
+
+        self.assertRaises(Exc, d.update, badseq())
+
+        self.assertRaises(ValueError, d.update, [(1, 2, 3)])
+
+    # no test_fromkeys or test_copy as both os.environ and selves don't support it
+
+    def test_get(self):
+        d = self._empty_mapping()
+        self.assertTrue(d.get(list(self.other.keys())[0]) is None)
+        self.assertEqual(d.get(list(self.other.keys())[0], 3), 3)
+        d = self.reference
+        self.assertTrue(d.get(list(self.other.keys())[0]) is None)
+        self.assertEqual(d.get(list(self.other.keys())[0], 3), 3)
+        self.assertEqual(d.get(list(self.inmapping.keys())[0]),
+                         list(self.inmapping.values())[0])
+        self.assertEqual(d.get(list(self.inmapping.keys())[0], 3),
+                         list(self.inmapping.values())[0])
+        self.assertRaises(TypeError, d.get)
+        self.assertRaises(TypeError, d.get, None, None, None)
+
+    def test_setdefault(self):
+        d = self._empty_mapping()
+        self.assertRaises(TypeError, d.setdefault)
+
+    def test_popitem(self):
+        d = self._empty_mapping()
+        self.assertRaises(KeyError, d.popitem)
+        self.assertRaises(TypeError, d.popitem, 42)
+
+    def test_pop(self):
+        d = self._empty_mapping()
+        k, v = list(self.inmapping.items())[0]
+        d[k] = v
+        self.assertRaises(KeyError, d.pop, list(self.other.keys())[0])
+
+        self.assertEqual(d.pop(k), v)
+        self.assertEqual(len(d), 0)
+
+        self.assertRaises(KeyError, d.pop, k)
+
+
+class TestMappingProtocol(BasicTestMappingProtocol):
+    def test_constructor(self):
+        BasicTestMappingProtocol.test_constructor(self)
+        self.assertTrue(self._empty_mapping() is not self._empty_mapping())
+        self.assertEqual(self.type2test(x=1, y=2), {"x": 1, "y": 2})
+
+    def test_bool(self):
+        BasicTestMappingProtocol.test_bool(self)
+        self.assertTrue(not self._empty_mapping())
+        self.assertTrue(self._full_mapping({"x": "y"}))
+        self.assertTrue(bool(self._empty_mapping()) is False)
+        self.assertTrue(bool(self._full_mapping({"x": "y"})) is True)
+
+    def test_keys(self):
+        BasicTestMappingProtocol.test_keys(self)
+        d = self._empty_mapping()
+        self.assertEqual(list(d.keys()), [])
+        d = self._full_mapping({'a': 1, 'b': 2})
+        k = d.keys()
+        self.assertIn('a', k)
+        self.assertIn('b', k)
+        self.assertNotIn('c', k)
+
+    def test_values(self):
+        BasicTestMappingProtocol.test_values(self)
+        d = self._full_mapping({1:2})
+        self.assertEqual(list(d.values()), [2])
+
+    def test_items(self):
+        BasicTestMappingProtocol.test_items(self)
+
+        d = self._full_mapping({1:2})
+        self.assertEqual(list(d.items()), [(1, 2)])
+
+    def test_contains(self):
+        d = self._empty_mapping()
+        self.assertNotIn('a', d)
+        self.assertTrue(not ('a' in d))
+        self.assertTrue('a' not in d)
+        d = self._full_mapping({'a': 1, 'b': 2})
+        self.assertIn('a', d)
+        self.assertIn('b', d)
+        self.assertNotIn('c', d)
+
+        self.assertRaises(TypeError, d.__contains__)
+
+    def test_len(self):
+        BasicTestMappingProtocol.test_len(self)
+        d = self._full_mapping({'a': 1, 'b': 2})
+        self.assertEqual(len(d), 2)
+
+    def test_getitem(self):
+        BasicTestMappingProtocol.test_getitem(self)
+        d = self._full_mapping({'a': 1, 'b': 2})
+        self.assertEqual(d['a'], 1)
+        self.assertEqual(d['b'], 2)
+        d['c'] = 3
+        d['a'] = 4
+        self.assertEqual(d['c'], 3)
+        self.assertEqual(d['a'], 4)
+        del d['b']
+        self.assertEqual(d, {'a': 4, 'c': 3})
+
+        self.assertRaises(TypeError, d.__getitem__)
+
+    def test_clear(self):
+        d = self._full_mapping({1:1, 2:2, 3:3})
+        d.clear()
+        self.assertEqual(d, {})
+
+        self.assertRaises(TypeError, d.clear, None)
+
+    def test_update(self):
+        BasicTestMappingProtocol.test_update(self)
+        # mapping argument
+        d = self._empty_mapping()
+        d.update({1:100})
+        d.update({2:20})
+        d.update({1:1, 2:2, 3:3})
+        self.assertEqual(d, {1:1, 2:2, 3:3})
+
+        # no argument
+        d.update()
+        self.assertEqual(d, {1:1, 2:2, 3:3})
+
+        # keyword arguments
+        d = self._empty_mapping()
+        d.update(x=100)
+        d.update(y=20)
+        d.update(x=1, y=2, z=3)
+        self.assertEqual(d, {"x":1, "y":2, "z":3})
+
+        # item sequence
+        d = self._empty_mapping()
+        d.update([("x", 100), ("y", 20)])
+        self.assertEqual(d, {"x":100, "y":20})
+
+        # Both item sequence and keyword arguments
+        d = self._empty_mapping()
+        d.update([("x", 100), ("y", 20)], x=1, y=2)
+        self.assertEqual(d, {"x":1, "y":2})
+
+        # iterator
+        d = self._full_mapping({1:3, 2:4})
+        d.update(self._full_mapping({1:2, 3:4, 5:6}).items())
+        self.assertEqual(d, {1:2, 2:4, 3:4, 5:6})
+
+        class SimpleUserDict:
+            def __init__(self):
+                self.d = {1:1, 2:2, 3:3}
+            def keys(self):
+                return self.d.keys()
+            def __getitem__(self, i):
+                return self.d[i]
+        d.clear()
+        d.update(SimpleUserDict())
+        self.assertEqual(d, {1:1, 2:2, 3:3})
+
+    def test_fromkeys(self):
+        self.assertEqual(self.type2test.fromkeys('abc'), {'a':None, 'b':None, 'c':None})
+        d = self._empty_mapping()
+        self.assertTrue(not(d.fromkeys('abc') is d))
+        self.assertEqual(d.fromkeys('abc'), {'a':None, 'b':None, 'c':None})
+        self.assertEqual(d.fromkeys((4,5),0), {4:0, 5:0})
+        self.assertEqual(d.fromkeys([]), {})
+        def g():
+            yield 1
+        self.assertEqual(d.fromkeys(g()), {1:None})
+        self.assertRaises(TypeError, {}.fromkeys, 3)
+        class dictlike(self.type2test): pass
+        self.assertEqual(dictlike.fromkeys('a'), {'a':None})
+        self.assertEqual(dictlike().fromkeys('a'), {'a':None})
+        self.assertTrue(dictlike.fromkeys('a').__class__ is dictlike)
+        self.assertTrue(dictlike().fromkeys('a').__class__ is dictlike)
+        self.assertTrue(type(dictlike.fromkeys('a')) is dictlike)
+        class mydict(self.type2test):
+            def __new__(cls):
+                return collections.UserDict()
+        ud = mydict.fromkeys('ab')
+        self.assertEqual(ud, {'a':None, 'b':None})
+        self.assertIsInstance(ud, collections.UserDict)
+        self.assertRaises(TypeError, dict.fromkeys)
+
+        class Exc(Exception): pass
+
+        class baddict1(self.type2test):
+            def __init__(self):
+                raise Exc()
+
+        self.assertRaises(Exc, baddict1.fromkeys, [1])
+
+        class BadSeq(object):
+            def __iter__(self):
+                return self
+            def __next__(self):
+                raise Exc()
+
+        self.assertRaises(Exc, self.type2test.fromkeys, BadSeq())
+
+        class baddict2(self.type2test):
+            def __setitem__(self, key, value):
+                raise Exc()
+
+        self.assertRaises(Exc, baddict2.fromkeys, [1])
+
+    def test_copy(self):
+        d = self._full_mapping({1:1, 2:2, 3:3})
+        self.assertEqual(d.copy(), {1:1, 2:2, 3:3})
+        d = self._empty_mapping()
+        self.assertEqual(d.copy(), d)
+        self.assertIsInstance(d.copy(), d.__class__)
+        self.assertRaises(TypeError, d.copy, None)
+
+    def test_get(self):
+        BasicTestMappingProtocol.test_get(self)
+        d = self._empty_mapping()
+        self.assertTrue(d.get('c') is None)
+        self.assertEqual(d.get('c', 3), 3)
+        d = self._full_mapping({'a' : 1, 'b' : 2})
+        self.assertTrue(d.get('c') is None)
+        self.assertEqual(d.get('c', 3), 3)
+        self.assertEqual(d.get('a'), 1)
+        self.assertEqual(d.get('a', 3), 1)
+
+    def test_setdefault(self):
+        BasicTestMappingProtocol.test_setdefault(self)
+        d = self._empty_mapping()
+        self.assertTrue(d.setdefault('key0') is None)
+        d.setdefault('key0', [])
+        self.assertTrue(d.setdefault('key0') is None)
+        d.setdefault('key', []).append(3)
+        self.assertEqual(d['key'][0], 3)
+        d.setdefault('key', []).append(4)
+        self.assertEqual(len(d['key']), 2)
+
+    def test_popitem(self):
+        BasicTestMappingProtocol.test_popitem(self)
+        for copymode in -1, +1:
+            # -1: b has same structure as a
+            # +1: b is a.copy()
+            for log2size in range(12):
+                size = 2**log2size
+                a = self._empty_mapping()
+                b = self._empty_mapping()
+                for i in range(size):
+                    a[repr(i)] = i
+                    if copymode < 0:
+                        b[repr(i)] = i
+                if copymode > 0:
+                    b = a.copy()
+                for i in range(size):
+                    ka, va = ta = a.popitem()
+                    self.assertEqual(va, int(ka))
+                    kb, vb = tb = b.popitem()
+                    self.assertEqual(vb, int(kb))
+                    self.assertTrue(not(copymode < 0 and ta != tb))
+                self.assertTrue(not a)
+                self.assertTrue(not b)
+
+    def test_pop(self):
+        BasicTestMappingProtocol.test_pop(self)
+
+        # Tests for pop with specified key
+        d = self._empty_mapping()
+        k, v = 'abc', 'def'
+
+        self.assertEqual(d.pop(k, v), v)
+        d[k] = v
+        self.assertEqual(d.pop(k, 1), v)
+
+
+class TestHashMappingProtocol(TestMappingProtocol):
+
+    def test_getitem(self):
+        TestMappingProtocol.test_getitem(self)
+        class Exc(Exception): pass
+
+        class BadEq(object):
+            def __eq__(self, other):
+                raise Exc()
+            def __hash__(self):
+                return 24
+
+        d = self._empty_mapping()
+        d[BadEq()] = 42
+        self.assertRaises(KeyError, d.__getitem__, 23)
+
+        class BadHash(object):
+            fail = False
+            def __hash__(self):
+                if self.fail:
+                    raise Exc()
+                else:
+                    return 42
+
+        d = self._empty_mapping()
+        x = BadHash()
+        d[x] = 42
+        x.fail = True
+        self.assertRaises(Exc, d.__getitem__, x)
+
+    def test_fromkeys(self):
+        TestMappingProtocol.test_fromkeys(self)
+        class mydict(self.type2test):
+            def __new__(cls):
+                return collections.UserDict()
+        ud = mydict.fromkeys('ab')
+        self.assertEqual(ud, {'a':None, 'b':None})
+        self.assertIsInstance(ud, collections.UserDict)
+
+    def test_pop(self):
+        TestMappingProtocol.test_pop(self)
+
+        class Exc(Exception): pass
+
+        class BadHash(object):
+            fail = False
+            def __hash__(self):
+                if self.fail:
+                    raise Exc()
+                else:
+                    return 42
+
+        d = self._empty_mapping()
+        x = BadHash()
+        d[x] = 42
+        x.fail = True
+        self.assertRaises(Exc, d.pop, x)
+
+    def test_mutatingiteration(self):
+        d = self._empty_mapping()
+        d[1] = 1
+        try:
+            for i in d:
+                d[i+1] = 1
+        except RuntimeError:
+            pass
+        else:
+            self.fail("changing dict size during iteration doesn't raise Error")
+
+    def test_repr(self):
+        d = self._empty_mapping()
+        self.assertEqual(repr(d), '{}')
+        d[1] = 2
+        self.assertEqual(repr(d), '{1: 2}')
+        d = self._empty_mapping()
+        d[1] = d
+        self.assertEqual(repr(d), '{1: {...}}')
+
+        class Exc(Exception): pass
+
+        class BadRepr(object):
+            def __repr__(self):
+                raise Exc()
+
+        d = self._full_mapping({1: BadRepr()})
+        self.assertRaises(Exc, repr, d)
+
+    def test_repr_deep(self):
+        d = self._empty_mapping()
+        for i in range(sys.getrecursionlimit() + 100):
+            d0 = d
+            d = self._empty_mapping()
+            d[1] = d0
+        self.assertRaises(RecursionError, repr, d)
+
+    def test_eq(self):
+        self.assertEqual(self._empty_mapping(), self._empty_mapping())
+        self.assertEqual(self._full_mapping({1: 2}),
+                         self._full_mapping({1: 2}))
+
+        class Exc(Exception): pass
+
+        class BadCmp(object):
+            def __eq__(self, other):
+                raise Exc()
+            def __hash__(self):
+                return 1
+
+        d1 = self._full_mapping({BadCmp(): 1})
+        d2 = self._full_mapping({1: 1})
+        self.assertRaises(Exc, lambda: BadCmp()==1)
+        self.assertRaises(Exc, lambda: d1==d2)
+
+    def test_setdefault(self):
+        TestMappingProtocol.test_setdefault(self)
+
+        class Exc(Exception): pass
+
+        class BadHash(object):
+            fail = False
+            def __hash__(self):
+                if self.fail:
+                    raise Exc()
+                else:
+                    return 42
+
+        d = self._empty_mapping()
+        x = BadHash()
+        d[x] = 42
+        x.fail = True
+        self.assertRaises(Exc, d.setdefault, x, [])
diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py
new file mode 100644
index 000000000..13be857f7
--- /dev/null
+++ b/Lib/test/test_dict.py
@@ -0,0 +1,1389 @@
+import collections
+import collections.abc
+import gc
+import pickle
+import random
+import string
+import sys
+import unittest
+import weakref
+from test import support
+
+
+class DictTest(unittest.TestCase):
+
+    def test_invalid_keyword_arguments(self):
+        class Custom(dict):
+            pass
+        for invalid in {1 : 2}, Custom({1 : 2}):
+            with self.assertRaises(TypeError):
+                dict(**invalid)
+            with self.assertRaises(TypeError):
+                {}.update(**invalid)
+
+    def test_constructor(self):
+        # calling built-in types without argument must return empty
+        self.assertEqual(dict(), {})
+        self.assertIsNot(dict(), {})
+
+    def test_literal_constructor(self):
+        # check literal constructor for different sized dicts
+        # (to exercise the BUILD_MAP oparg).
+        for n in (0, 1, 6, 256, 400):
+            items = [(''.join(random.sample(string.ascii_letters, 8)), i)
+                     for i in range(n)]
+            random.shuffle(items)
+            formatted_items = ('{!r}: {:d}'.format(k, v) for k, v in items)
+            dictliteral = '{' + ', '.join(formatted_items) + '}'
+            self.assertEqual(eval(dictliteral), dict(items))
+
+    def test_bool(self):
+        self.assertIs(not {}, True)
+        self.assertTrue({1: 2})
+        self.assertIs(bool({}), False)
+        self.assertIs(bool({1: 2}), True)
+
+    def test_keys(self):
+        d = {}
+        self.assertEqual(set(d.keys()), set())
+        d = {'a': 1, 'b': 2}
+        k = d.keys()
+        self.assertEqual(set(k), {'a', 'b'})
+        self.assertIn('a', k)
+        self.assertIn('b', k)
+        self.assertIn('a', d)
+        self.assertIn('b', d)
+        self.assertRaises(TypeError, d.keys, None)
+        self.assertEqual(repr(dict(a=1).keys()), "dict_keys(['a'])")
+
+    def test_values(self):
+        d = {}
+        self.assertEqual(set(d.values()), set())
+        d = {1:2}
+        self.assertEqual(set(d.values()), {2})
+        self.assertRaises(TypeError, d.values, None)
+        self.assertEqual(repr(dict(a=1).values()), "dict_values([1])")
+
+    def test_items(self):
+        d = {}
+        self.assertEqual(set(d.items()), set())
+
+        d = {1:2}
+        self.assertEqual(set(d.items()), {(1, 2)})
+        self.assertRaises(TypeError, d.items, None)
+        self.assertEqual(repr(dict(a=1).items()), "dict_items([('a', 1)])")
+
+    def test_contains(self):
+        d = {}
+        self.assertNotIn('a', d)
+        self.assertFalse('a' in d)
+        self.assertTrue('a' not in d)
+        d = {'a': 1, 'b': 2}
+        self.assertIn('a', d)
+        self.assertIn('b', d)
+        self.assertNotIn('c', d)
+
+        self.assertRaises(TypeError, d.__contains__)
+
+    def test_len(self):
+        d = {}
+        self.assertEqual(len(d), 0)
+        d = {'a': 1, 'b': 2}
+        self.assertEqual(len(d), 2)
+
+    def test_getitem(self):
+        d = {'a': 1, 'b': 2}
+        self.assertEqual(d['a'], 1)
+        self.assertEqual(d['b'], 2)
+        d['c'] = 3
+        d['a'] = 4
+        self.assertEqual(d['c'], 3)
+        self.assertEqual(d['a'], 4)
+        del d['b']
+        self.assertEqual(d, {'a': 4, 'c': 3})
+
+        self.assertRaises(TypeError, d.__getitem__)
+
+        class BadEq(object):
+            def __eq__(self, other):
+                raise Exc()
+            def __hash__(self):
+                return 24
+
+        d = {}
+        d[BadEq()] = 42
+        self.assertRaises(KeyError, d.__getitem__, 23)
+
+        class Exc(Exception): pass
+
+        class BadHash(object):
+            fail = False
+            def __hash__(self):
+                if self.fail:
+                    raise Exc()
+                else:
+                    return 42
+
+        x = BadHash()
+        d[x] = 42
+        x.fail = True
+        self.assertRaises(Exc, d.__getitem__, x)
+
+    def test_clear(self):
+        d = {1:1, 2:2, 3:3}
+        d.clear()
+        self.assertEqual(d, {})
+
+        self.assertRaises(TypeError, d.clear, None)
+
+    def test_update(self):
+        d = {}
+        d.update({1:100})
+        d.update({2:20})
+        d.update({1:1, 2:2, 3:3})
+        self.assertEqual(d, {1:1, 2:2, 3:3})
+
+        d.update()
+        self.assertEqual(d, {1:1, 2:2, 3:3})
+
+        self.assertRaises((TypeError, AttributeError), d.update, None)
+
+        class SimpleUserDict:
+            def __init__(self):
+                self.d = {1:1, 2:2, 3:3}
+            def keys(self):
+                return self.d.keys()
+            def __getitem__(self, i):
+                return self.d[i]
+        d.clear()
+        d.update(SimpleUserDict())
+        self.assertEqual(d, {1:1, 2:2, 3:3})
+
+        class Exc(Exception): pass
+
+        d.clear()
+        class FailingUserDict:
+            def keys(self):
+                raise Exc
+        self.assertRaises(Exc, d.update, FailingUserDict())
+
+        class FailingUserDict:
+            def keys(self):
+                class BogonIter:
+                    def __init__(self):
+                        self.i = 1
+                    def __iter__(self):
+                        return self
+                    def __next__(self):
+                        if self.i:
+                            self.i = 0
+                            return 'a'
+                        raise Exc
+                return BogonIter()
+            def __getitem__(self, key):
+                return key
+        self.assertRaises(Exc, d.update, FailingUserDict())
+
+        class FailingUserDict:
+            def keys(self):
+                class BogonIter:
+                    def __init__(self):
+                        self.i = ord('a')
+                    def __iter__(self):
+                        return self
+                    def __next__(self):
+                        if self.i <= ord('z'):
+                            rtn = chr(self.i)
+                            self.i += 1
+                            return rtn
+                        raise StopIteration
+                return BogonIter()
+            def __getitem__(self, key):
+                raise Exc
+        self.assertRaises(Exc, d.update, FailingUserDict())
+
+        class badseq(object):
+            def __iter__(self):
+                return self
+            def __next__(self):
+                raise Exc()
+
+        self.assertRaises(Exc, {}.update, badseq())
+
+        self.assertRaises(ValueError, {}.update, [(1, 2, 3)])
+
+    def test_fromkeys(self):
+        self.assertEqual(dict.fromkeys('abc'), {'a':None, 'b':None, 'c':None})
+        d = {}
+        self.assertIsNot(d.fromkeys('abc'), d)
+        self.assertEqual(d.fromkeys('abc'), {'a':None, 'b':None, 'c':None})
+        self.assertEqual(d.fromkeys((4,5),0), {4:0, 5:0})
+        self.assertEqual(d.fromkeys([]), {})
+        def g():
+            yield 1
+        self.assertEqual(d.fromkeys(g()), {1:None})
+        self.assertRaises(TypeError, {}.fromkeys, 3)
+        class dictlike(dict): pass
+        self.assertEqual(dictlike.fromkeys('a'), {'a':None})
+        self.assertEqual(dictlike().fromkeys('a'), {'a':None})
+        self.assertIsInstance(dictlike.fromkeys('a'), dictlike)
+        self.assertIsInstance(dictlike().fromkeys('a'), dictlike)
+        class mydict(dict):
+            def __new__(cls):
+                return collections.UserDict()
+        ud = mydict.fromkeys('ab')
+        self.assertEqual(ud, {'a':None, 'b':None})
+        self.assertIsInstance(ud, collections.UserDict)
+        self.assertRaises(TypeError, dict.fromkeys)
+
+        class Exc(Exception): pass
+
+        class baddict1(dict):
+            def __init__(self):
+                raise Exc()
+
+        self.assertRaises(Exc, baddict1.fromkeys, [1])
+
+        class BadSeq(object):
+            def __iter__(self):
+                return self
+            def __next__(self):
+                raise Exc()
+
+        self.assertRaises(Exc, dict.fromkeys, BadSeq())
+
+        class baddict2(dict):
+            def __setitem__(self, key, value):
+                raise Exc()
+
+        self.assertRaises(Exc, baddict2.fromkeys, [1])
+
+        # test fast path for dictionary inputs
+        d = dict(zip(range(6), range(6)))
+        self.assertEqual(dict.fromkeys(d, 0), dict(zip(range(6), [0]*6)))
+
+        class baddict3(dict):
+            def __new__(cls):
+                return d
+        d = {i : i for i in range(10)}
+        res = d.copy()
+        res.update(a=None, b=None, c=None)
+        self.assertEqual(baddict3.fromkeys({"a", "b", "c"}), res)
+
+    def test_copy(self):
+        d = {1: 1, 2: 2, 3: 3}
+        self.assertIsNot(d.copy(), d)
+        self.assertEqual(d.copy(), d)
+        self.assertEqual(d.copy(), {1: 1, 2: 2, 3: 3})
+
+        copy = d.copy()
+        d[4] = 4
+        self.assertNotEqual(copy, d)
+
+        self.assertEqual({}.copy(), {})
+        self.assertRaises(TypeError, d.copy, None)
+
+    def test_copy_fuzz(self):
+        for dict_size in [10, 100, 1000, 10000, 100000]:
+            dict_size = random.randrange(
+                dict_size // 2, dict_size + dict_size // 2)
+            with self.subTest(dict_size=dict_size):
+                d = {}
+                for i in range(dict_size):
+                    d[i] = i
+
+                d2 = d.copy()
+                self.assertIsNot(d2, d)
+                self.assertEqual(d, d2)
+                d2['key'] = 'value'
+                self.assertNotEqual(d, d2)
+                self.assertEqual(len(d2), len(d) + 1)
+
+    def test_copy_maintains_tracking(self):
+        class A:
+            pass
+
+        key = A()
+
+        for d in ({}, {'a': 1}, {key: 'val'}):
+            d2 = d.copy()
+            self.assertEqual(gc.is_tracked(d), gc.is_tracked(d2))
+
+    def test_copy_noncompact(self):
+        # Dicts don't compact themselves on del/pop operations.
+        # Copy will use a slow merging strategy that produces
+        # a compacted copy when roughly 33% of dict is a non-used
+        # keys-space (to optimize memory footprint).
+        # In this test we want to hit the slow/compacting
+        # branch of dict.copy() and make sure it works OK.
+        d = {k: k for k in range(1000)}
+        for k in range(950):
+            del d[k]
+        d2 = d.copy()
+        self.assertEqual(d2, d)
+
+    def test_get(self):
+        d = {}
+        self.assertIs(d.get('c'), None)
+        self.assertEqual(d.get('c', 3), 3)
+        d = {'a': 1, 'b': 2}
+        self.assertIs(d.get('c'), None)
+        self.assertEqual(d.get('c', 3), 3)
+        self.assertEqual(d.get('a'), 1)
+        self.assertEqual(d.get('a', 3), 1)
+        self.assertRaises(TypeError, d.get)
+        self.assertRaises(TypeError, d.get, None, None, None)
+
+    def test_setdefault(self):
+        # dict.setdefault()
+        d = {}
+        self.assertIs(d.setdefault('key0'), None)
+        d.setdefault('key0', [])
+        self.assertIs(d.setdefault('key0'), None)
+        d.setdefault('key', []).append(3)
+        self.assertEqual(d['key'][0], 3)
+        d.setdefault('key', []).append(4)
+        self.assertEqual(len(d['key']), 2)
+        self.assertRaises(TypeError, d.setdefault)
+
+        class Exc(Exception): pass
+
+        class BadHash(object):
+            fail = False
+            def __hash__(self):
+                if self.fail:
+                    raise Exc()
+                else:
+                    return 42
+
+        x = BadHash()
+        d[x] = 42
+        x.fail = True
+        self.assertRaises(Exc, d.setdefault, x, [])
+
+    def test_setdefault_atomic(self):
+        # Issue #13521: setdefault() calls __hash__ and __eq__ only once.
+        class Hashed(object):
+            def __init__(self):
+                self.hash_count = 0
+                self.eq_count = 0
+            def __hash__(self):
+                self.hash_count += 1
+                return 42
+            def __eq__(self, other):
+                self.eq_count += 1
+                return id(self) == id(other)
+        hashed1 = Hashed()
+        y = {hashed1: 5}
+        hashed2 = Hashed()
+        y.setdefault(hashed2, [])
+        self.assertEqual(hashed1.hash_count, 1)
+        self.assertEqual(hashed2.hash_count, 1)
+        self.assertEqual(hashed1.eq_count + hashed2.eq_count, 1)
+
+    def test_setitem_atomic_at_resize(self):
+        class Hashed(object):
+            def __init__(self):
+                self.hash_count = 0
+                self.eq_count = 0
+            def __hash__(self):
+                self.hash_count += 1
+                return 42
+            def __eq__(self, other):
+                self.eq_count += 1
+                return id(self) == id(other)
+        hashed1 = Hashed()
+        # 5 items
+        y = {hashed1: 5, 0: 0, 1: 1, 2: 2, 3: 3}
+        hashed2 = Hashed()
+        # 6th item forces a resize
+        y[hashed2] = []
+        self.assertEqual(hashed1.hash_count, 1)
+        self.assertEqual(hashed2.hash_count, 1)
+        self.assertEqual(hashed1.eq_count + hashed2.eq_count, 1)
+
+    def test_popitem(self):
+        # dict.popitem()
+        for copymode in -1, +1:
+            # -1: b has same structure as a
+            # +1: b is a.copy()
+            for log2size in range(12):
+                size = 2**log2size
+                a = {}
+                b = {}
+                for i in range(size):
+                    a[repr(i)] = i
+                    if copymode < 0:
+                        b[repr(i)] = i
+                if copymode > 0:
+                    b = a.copy()
+                for i in range(size):
+                    ka, va = ta = a.popitem()
+                    self.assertEqual(va, int(ka))
+                    kb, vb = tb = b.popitem()
+                    self.assertEqual(vb, int(kb))
+                    self.assertFalse(copymode < 0 and ta != tb)
+                self.assertFalse(a)
+                self.assertFalse(b)
+
+        d = {}
+        self.assertRaises(KeyError, d.popitem)
+
+    def test_pop(self):
+        # Tests for pop with specified key
+        d = {}
+        k, v = 'abc', 'def'
+        d[k] = v
+        self.assertRaises(KeyError, d.pop, 'ghi')
+
+        self.assertEqual(d.pop(k), v)
+        self.assertEqual(len(d), 0)
+
+        self.assertRaises(KeyError, d.pop, k)
+
+        self.assertEqual(d.pop(k, v), v)
+        d[k] = v
+        self.assertEqual(d.pop(k, 1), v)
+
+        self.assertRaises(TypeError, d.pop)
+
+        class Exc(Exception): pass
+
+        class BadHash(object):
+            fail = False
+            def __hash__(self):
+                if self.fail:
+                    raise Exc()
+                else:
+                    return 42
+
+        x = BadHash()
+        d[x] = 42
+        x.fail = True
+        self.assertRaises(Exc, d.pop, x)
+
+    def test_mutating_iteration(self):
+        # changing dict size during iteration
+        d = {}
+        d[1] = 1
+        with self.assertRaises(RuntimeError):
+            for i in d:
+                d[i+1] = 1
+
+    def test_mutating_iteration_delete(self):
+        # change dict content during iteration
+        d = {}
+        d[0] = 0
+        with self.assertRaises(RuntimeError):
+            for i in d:
+                del d[0]
+                d[0] = 0
+
+    def test_mutating_iteration_delete_over_values(self):
+        # change dict content during iteration
+        d = {}
+        d[0] = 0
+        with self.assertRaises(RuntimeError):
+            for i in d.values():
+                del d[0]
+                d[0] = 0
+
+    def test_mutating_iteration_delete_over_items(self):
+        # change dict content during iteration
+        d = {}
+        d[0] = 0
+        with self.assertRaises(RuntimeError):
+            for i in d.items():
+                del d[0]
+                d[0] = 0
+
+    def test_mutating_lookup(self):
+        # changing dict during a lookup (issue #14417)
+        class NastyKey:
+            mutate_dict = None
+
+            def __init__(self, value):
+                self.value = value
+
+            def __hash__(self):
+                # hash collision!
+                return 1
+
+            def __eq__(self, other):
+                if NastyKey.mutate_dict:
+                    mydict, key = NastyKey.mutate_dict
+                    NastyKey.mutate_dict = None
+                    del mydict[key]
+                return self.value == other.value
+
+        key1 = NastyKey(1)
+        key2 = NastyKey(2)
+        d = {key1: 1}
+        NastyKey.mutate_dict = (d, key1)
+        d[key2] = 2
+        self.assertEqual(d, {key2: 2})
+
+    def test_repr(self):
+        d = {}
+        self.assertEqual(repr(d), '{}')
+        d[1] = 2
+        self.assertEqual(repr(d), '{1: 2}')
+        d = {}
+        d[1] = d
+        self.assertEqual(repr(d), '{1: {...}}')
+
+        class Exc(Exception): pass
+
+        class BadRepr(object):
+            def __repr__(self):
+                raise Exc()
+
+        d = {1: BadRepr()}
+        self.assertRaises(Exc, repr, d)
+
+    def test_repr_deep(self):
+        d = {}
+        for i in range(sys.getrecursionlimit() + 100):
+            d = {1: d}
+        self.assertRaises(RecursionError, repr, d)
+
+    def test_eq(self):
+        self.assertEqual({}, {})
+        self.assertEqual({1: 2}, {1: 2})
+
+        class Exc(Exception): pass
+
+        class BadCmp(object):
+            def __eq__(self, other):
+                raise Exc()
+            def __hash__(self):
+                return 1
+
+        d1 = {BadCmp(): 1}
+        d2 = {1: 1}
+
+        with self.assertRaises(Exc):
+            d1 == d2
+
+    def test_keys_contained(self):
+        self.helper_keys_contained(lambda x: x.keys())
+        self.helper_keys_contained(lambda x: x.items())
+
+    def helper_keys_contained(self, fn):
+        # Test rich comparisons against dict key views, which should behave the
+        # same as sets.
+        empty = fn(dict())
+        empty2 = fn(dict())
+        smaller = fn({1:1, 2:2})
+        larger = fn({1:1, 2:2, 3:3})
+        larger2 = fn({1:1, 2:2, 3:3})
+        larger3 = fn({4:1, 2:2, 3:3})
+
+        self.assertTrue(smaller <  larger)
+        self.assertTrue(smaller <= larger)
+        self.assertTrue(larger >  smaller)
+        self.assertTrue(larger >= smaller)
+
+        self.assertFalse(smaller >= larger)
+        self.assertFalse(smaller >  larger)
+        self.assertFalse(larger  <= smaller)
+        self.assertFalse(larger  <  smaller)
+
+        self.assertFalse(smaller <  larger3)
+        self.assertFalse(smaller <= larger3)
+        self.assertFalse(larger3 >  smaller)
+        self.assertFalse(larger3 >= smaller)
+
+        # Inequality strictness
+        self.assertTrue(larger2 >= larger)
+        self.assertTrue(larger2 <= larger)
+        self.assertFalse(larger2 > larger)
+        self.assertFalse(larger2 < larger)
+
+        self.assertTrue(larger == larger2)
+        self.assertTrue(smaller != larger)
+
+        # There is an optimization on the zero-element case.
+        self.assertTrue(empty == empty2)
+        self.assertFalse(empty != empty2)
+        self.assertFalse(empty == smaller)
+        self.assertTrue(empty != smaller)
+
+        # With the same size, an elementwise compare happens
+        self.assertTrue(larger != larger3)
+        self.assertFalse(larger == larger3)
+
+    def test_errors_in_view_containment_check(self):
+        class C:
+            def __eq__(self, other):
+                raise RuntimeError
+
+        d1 = {1: C()}
+        d2 = {1: C()}
+        with self.assertRaises(RuntimeError):
+            d1.items() == d2.items()
+        with self.assertRaises(RuntimeError):
+            d1.items() != d2.items()
+        with self.assertRaises(RuntimeError):
+            d1.items() <= d2.items()
+        with self.assertRaises(RuntimeError):
+            d1.items() >= d2.items()
+
+        d3 = {1: C(), 2: C()}
+        with self.assertRaises(RuntimeError):
+            d2.items() < d3.items()
+        with self.assertRaises(RuntimeError):
+            d3.items() > d2.items()
+
+    def test_dictview_set_operations_on_keys(self):
+        k1 = {1:1, 2:2}.keys()
+        k2 = {1:1, 2:2, 3:3}.keys()
+        k3 = {4:4}.keys()
+
+        self.assertEqual(k1 - k2, set())
+        self.assertEqual(k1 - k3, {1,2})
+        self.assertEqual(k2 - k1, {3})
+        self.assertEqual(k3 - k1, {4})
+        self.assertEqual(k1 & k2, {1,2})
+        self.assertEqual(k1 & k3, set())
+        self.assertEqual(k1 | k2, {1,2,3})
+        self.assertEqual(k1 ^ k2, {3})
+        self.assertEqual(k1 ^ k3, {1,2,4})
+
+    def test_dictview_set_operations_on_items(self):
+        k1 = {1:1, 2:2}.items()
+        k2 = {1:1, 2:2, 3:3}.items()
+        k3 = {4:4}.items()
+
+        self.assertEqual(k1 - k2, set())
+        self.assertEqual(k1 - k3, {(1,1), (2,2)})
+        self.assertEqual(k2 - k1, {(3,3)})
+        self.assertEqual(k3 - k1, {(4,4)})
+        self.assertEqual(k1 & k2, {(1,1), (2,2)})
+        self.assertEqual(k1 & k3, set())
+        self.assertEqual(k1 | k2, {(1,1), (2,2), (3,3)})
+        self.assertEqual(k1 ^ k2, {(3,3)})
+        self.assertEqual(k1 ^ k3, {(1,1), (2,2), (4,4)})
+
+    def test_dictview_mixed_set_operations(self):
+        # Just a few for .keys()
+        self.assertTrue({1:1}.keys() == {1})
+        self.assertTrue({1} == {1:1}.keys())
+        self.assertEqual({1:1}.keys() | {2}, {1, 2})
+        self.assertEqual({2} | {1:1}.keys(), {1, 2})
+        # And a few for .items()
+        self.assertTrue({1:1}.items() == {(1,1)})
+        self.assertTrue({(1,1)} == {1:1}.items())
+        self.assertEqual({1:1}.items() | {2}, {(1,1), 2})
+        self.assertEqual({2} | {1:1}.items(), {(1,1), 2})
+
+    def test_missing(self):
+        # Make sure dict doesn't have a __missing__ method
+        self.assertFalse(hasattr(dict, "__missing__"))
+        self.assertFalse(hasattr({}, "__missing__"))
+        # Test several cases:
+        # (D) subclass defines __missing__ method returning a value
+        # (E) subclass defines __missing__ method raising RuntimeError
+        # (F) subclass sets __missing__ instance variable (no effect)
+        # (G) subclass doesn't define __missing__ at all
+        class D(dict):
+            def __missing__(self, key):
+                return 42
+        d = D({1: 2, 3: 4})
+        self.assertEqual(d[1], 2)
+        self.assertEqual(d[3], 4)
+        self.assertNotIn(2, d)
+        self.assertNotIn(2, d.keys())
+        self.assertEqual(d[2], 42)
+
+        class E(dict):
+            def __missing__(self, key):
+                raise RuntimeError(key)
+        e = E()
+        with self.assertRaises(RuntimeError) as c:
+            e[42]
+        self.assertEqual(c.exception.args, (42,))
+
+        class F(dict):
+            def __init__(self):
+                # An instance variable __missing__ should have no effect
+                self.__missing__ = lambda key: None
+        f = F()
+        with self.assertRaises(KeyError) as c:
+            f[42]
+        self.assertEqual(c.exception.args, (42,))
+
+        class G(dict):
+            pass
+        g = G()
+        with self.assertRaises(KeyError) as c:
+            g[42]
+        self.assertEqual(c.exception.args, (42,))
+
+    def test_tuple_keyerror(self):
+        # SF #1576657
+        d = {}
+        with self.assertRaises(KeyError) as c:
+            d[(1,)]
+        self.assertEqual(c.exception.args, ((1,),))
+
+    def test_bad_key(self):
+        # Dictionary lookups should fail if __eq__() raises an exception.
+        class CustomException(Exception):
+            pass
+
+        class BadDictKey:
+            def __hash__(self):
+                return hash(self.__class__)
+
+            def __eq__(self, other):
+                if isinstance(other, self.__class__):
+                    raise CustomException
+                return other
+
+        d = {}
+        x1 = BadDictKey()
+        x2 = BadDictKey()
+        d[x1] = 1
+        for stmt in ['d[x2] = 2',
+                     'z = d[x2]',
+                     'x2 in d',
+                     'd.get(x2)',
+                     'd.setdefault(x2, 42)',
+                     'd.pop(x2)',
+                     'd.update({x2: 2})']:
+            with self.assertRaises(CustomException):
+                exec(stmt, locals())
+
+    def test_resize1(self):
+        # Dict resizing bug, found by Jack Jansen in 2.2 CVS development.
+        # This version got an assert failure in debug build, infinite loop in
+        # release build.  Unfortunately, provoking this kind of stuff requires
+        # a mix of inserts and deletes hitting exactly the right hash codes in
+        # exactly the right order, and I can't think of a randomized approach
+        # that would be *likely* to hit a failing case in reasonable time.
+
+        d = {}
+        for i in range(5):
+            d[i] = i
+        for i in range(5):
+            del d[i]
+        for i in range(5, 9):  # i==8 was the problem
+            d[i] = i
+
+    def test_resize2(self):
+        # Another dict resizing bug (SF bug #1456209).
+        # This caused Segmentation faults or Illegal instructions.
+
+        class X(object):
+            def __hash__(self):
+                return 5
+            def __eq__(self, other):
+                if resizing:
+                    d.clear()
+                return False
+        d = {}
+        resizing = False
+        d[X()] = 1
+        d[X()] = 2
+        d[X()] = 3
+        d[X()] = 4
+        d[X()] = 5
+        # now trigger a resize
+        resizing = True
+        d[9] = 6
+
+    def test_empty_presized_dict_in_freelist(self):
+        # Bug #3537: if an empty but presized dict with a size larger
+        # than 7 was in the freelist, it triggered an assertion failure
+        with self.assertRaises(ZeroDivisionError):
+            d = {'a': 1 // 0, 'b': None, 'c': None, 'd': None, 'e': None,
+                 'f': None, 'g': None, 'h': None}
+        d = {}
+
+    def test_container_iterator(self):
+        # Bug #3680: tp_traverse was not implemented for dictiter and
+        # dictview objects.
+        class C(object):
+            pass
+        views = (dict.items, dict.values, dict.keys)
+        for v in views:
+            obj = C()
+            ref = weakref.ref(obj)
+            container = {obj: 1}
+            obj.v = v(container)
+            obj.x = iter(obj.v)
+            del obj, container
+            gc.collect()
+            self.assertIs(ref(), None, "Cycle was not collected")
+
+    def _not_tracked(self, t):
+        # Nested containers can take several collections to untrack
+        gc.collect()
+        gc.collect()
+        self.assertFalse(gc.is_tracked(t), t)
+
+    def _tracked(self, t):
+        self.assertTrue(gc.is_tracked(t), t)
+        gc.collect()
+        gc.collect()
+        self.assertTrue(gc.is_tracked(t), t)
+
+    @support.cpython_only
+    def test_track_literals(self):
+        # Test GC-optimization of dict literals
+        x, y, z, w = 1.5, "a", (1, None), []
+
+        self._not_tracked({})
+        self._not_tracked({x:(), y:x, z:1})
+        self._not_tracked({1: "a", "b": 2})
+        self._not_tracked({1: 2, (None, True, False, ()): int})
+        self._not_tracked({1: object()})
+
+        # Dicts with mutable elements are always tracked, even if those
+        # elements are not tracked right now.
+        self._tracked({1: []})
+        self._tracked({1: ([],)})
+        self._tracked({1: {}})
+        self._tracked({1: set()})
+
+    @support.cpython_only
+    def test_track_dynamic(self):
+        # Test GC-optimization of dynamically-created dicts
+        class MyObject(object):
+            pass
+        x, y, z, w, o = 1.5, "a", (1, object()), [], MyObject()
+
+        d = dict()
+        self._not_tracked(d)
+        d[1] = "a"
+        self._not_tracked(d)
+        d[y] = 2
+        self._not_tracked(d)
+        d[z] = 3
+        self._not_tracked(d)
+        self._not_tracked(d.copy())
+        d[4] = w
+        self._tracked(d)
+        self._tracked(d.copy())
+        d[4] = None
+        self._not_tracked(d)
+        self._not_tracked(d.copy())
+
+        # dd isn't tracked right now, but it may mutate and therefore d
+        # which contains it must be tracked.
+        d = dict()
+        dd = dict()
+        d[1] = dd
+        self._not_tracked(dd)
+        self._tracked(d)
+        dd[1] = d
+        self._tracked(dd)
+
+        d = dict.fromkeys([x, y, z])
+        self._not_tracked(d)
+        dd = dict()
+        dd.update(d)
+        self._not_tracked(dd)
+        d = dict.fromkeys([x, y, z, o])
+        self._tracked(d)
+        dd = dict()
+        dd.update(d)
+        self._tracked(dd)
+
+        d = dict(x=x, y=y, z=z)
+        self._not_tracked(d)
+        d = dict(x=x, y=y, z=z, w=w)
+        self._tracked(d)
+        d = dict()
+        d.update(x=x, y=y, z=z)
+        self._not_tracked(d)
+        d.update(w=w)
+        self._tracked(d)
+
+        d = dict([(x, y), (z, 1)])
+        self._not_tracked(d)
+        d = dict([(x, y), (z, w)])
+        self._tracked(d)
+        d = dict()
+        d.update([(x, y), (z, 1)])
+        self._not_tracked(d)
+        d.update([(x, y), (z, w)])
+        self._tracked(d)
+
+    @support.cpython_only
+    def test_track_subtypes(self):
+        # Dict subtypes are always tracked
+        class MyDict(dict):
+            pass
+        self._tracked(MyDict())
+
+    def make_shared_key_dict(self, n):
+        class C:
+            pass
+
+        dicts = []
+        for i in range(n):
+            a = C()
+            a.x, a.y, a.z = 1, 2, 3
+            dicts.append(a.__dict__)
+
+        return dicts
+
+    @support.cpython_only
+    def test_splittable_setdefault(self):
+        """split table must be combined when setdefault()
+        breaks insertion order"""
+        a, b = self.make_shared_key_dict(2)
+
+        a['a'] = 1
+        size_a = sys.getsizeof(a)
+        a['b'] = 2
+        b.setdefault('b', 2)
+        size_b = sys.getsizeof(b)
+        b['a'] = 1
+
+        self.assertGreater(size_b, size_a)
+        self.assertEqual(list(a), ['x', 'y', 'z', 'a', 'b'])
+        self.assertEqual(list(b), ['x', 'y', 'z', 'b', 'a'])
+
+    @support.cpython_only
+    def test_splittable_del(self):
+        """split table must be combined when del d[k]"""
+        a, b = self.make_shared_key_dict(2)
+
+        orig_size = sys.getsizeof(a)
+
+        del a['y']  # split table is combined
+        with self.assertRaises(KeyError):
+            del a['y']
+
+        self.assertGreater(sys.getsizeof(a), orig_size)
+        self.assertEqual(list(a), ['x', 'z'])
+        self.assertEqual(list(b), ['x', 'y', 'z'])
+
+        # Two dicts have different insertion order.
+        a['y'] = 42
+        self.assertEqual(list(a), ['x', 'z', 'y'])
+        self.assertEqual(list(b), ['x', 'y', 'z'])
+
+    @support.cpython_only
+    def test_splittable_pop(self):
+        """split table must be combined when d.pop(k)"""
+        a, b = self.make_shared_key_dict(2)
+
+        orig_size = sys.getsizeof(a)
+
+        a.pop('y')  # split table is combined
+        with self.assertRaises(KeyError):
+            a.pop('y')
+
+        self.assertGreater(sys.getsizeof(a), orig_size)
+        self.assertEqual(list(a), ['x', 'z'])
+        self.assertEqual(list(b), ['x', 'y', 'z'])
+
+        # Two dicts have different insertion order.
+        a['y'] = 42
+        self.assertEqual(list(a), ['x', 'z', 'y'])
+        self.assertEqual(list(b), ['x', 'y', 'z'])
+
+    @support.cpython_only
+    def test_splittable_pop_pending(self):
+        """pop a pending key in a splitted table should not crash"""
+        a, b = self.make_shared_key_dict(2)
+
+        a['a'] = 4
+        with self.assertRaises(KeyError):
+            b.pop('a')
+
+    @support.cpython_only
+    def test_splittable_popitem(self):
+        """split table must be combined when d.popitem()"""
+        a, b = self.make_shared_key_dict(2)
+
+        orig_size = sys.getsizeof(a)
+
+        item = a.popitem()  # split table is combined
+        self.assertEqual(item, ('z', 3))
+        with self.assertRaises(KeyError):
+            del a['z']
+
+        self.assertGreater(sys.getsizeof(a), orig_size)
+        self.assertEqual(list(a), ['x', 'y'])
+        self.assertEqual(list(b), ['x', 'y', 'z'])
+
+    @support.cpython_only
+    def test_splittable_setattr_after_pop(self):
+        """setattr() must not convert combined table into split table."""
+        # Issue 28147
+        import _testcapi
+
+        class C:
+            pass
+        a = C()
+
+        a.a = 1
+        self.assertTrue(_testcapi.dict_hassplittable(a.__dict__))
+
+        # dict.pop() convert it to combined table
+        a.__dict__.pop('a')
+        self.assertFalse(_testcapi.dict_hassplittable(a.__dict__))
+
+        # But C should not convert a.__dict__ to split table again.
+        a.a = 1
+        self.assertFalse(_testcapi.dict_hassplittable(a.__dict__))
+
+        # Same for popitem()
+        a = C()
+        a.a = 2
+        self.assertTrue(_testcapi.dict_hassplittable(a.__dict__))
+        a.__dict__.popitem()
+        self.assertFalse(_testcapi.dict_hassplittable(a.__dict__))
+        a.a = 3
+        self.assertFalse(_testcapi.dict_hassplittable(a.__dict__))
+
+    def test_iterator_pickling(self):
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            data = {1:"a", 2:"b", 3:"c"}
+            it = iter(data)
+            d = pickle.dumps(it, proto)
+            it = pickle.loads(d)
+            self.assertEqual(list(it), list(data))
+
+            it = pickle.loads(d)
+            try:
+                drop = next(it)
+            except StopIteration:
+                continue
+            d = pickle.dumps(it, proto)
+            it = pickle.loads(d)
+            del data[drop]
+            self.assertEqual(list(it), list(data))
+
+    def test_itemiterator_pickling(self):
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            data = {1:"a", 2:"b", 3:"c"}
+            # dictviews aren't picklable, only their iterators
+            itorg = iter(data.items())
+            d = pickle.dumps(itorg, proto)
+            it = pickle.loads(d)
+            # note that the type of the unpickled iterator
+            # is not necessarily the same as the original.  It is
+            # merely an object supporting the iterator protocol, yielding
+            # the same objects as the original one.
+            # self.assertEqual(type(itorg), type(it))
+            self.assertIsInstance(it, collections.abc.Iterator)
+            self.assertEqual(dict(it), data)
+
+            it = pickle.loads(d)
+            drop = next(it)
+            d = pickle.dumps(it, proto)
+            it = pickle.loads(d)
+            del data[drop[0]]
+            self.assertEqual(dict(it), data)
+
+    def test_valuesiterator_pickling(self):
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            data = {1:"a", 2:"b", 3:"c"}
+            # data.values() isn't picklable, only its iterator
+            it = iter(data.values())
+            d = pickle.dumps(it, proto)
+            it = pickle.loads(d)
+            self.assertEqual(list(it), list(data.values()))
+
+            it = pickle.loads(d)
+            drop = next(it)
+            d = pickle.dumps(it, proto)
+            it = pickle.loads(d)
+            values = list(it) + [drop]
+            self.assertEqual(sorted(values), sorted(list(data.values())))
+
+    def test_reverseiterator_pickling(self):
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            data = {1:"a", 2:"b", 3:"c"}
+            it = reversed(data)
+            d = pickle.dumps(it, proto)
+            it = pickle.loads(d)
+            self.assertEqual(list(it), list(reversed(data)))
+
+            it = pickle.loads(d)
+            try:
+                drop = next(it)
+            except StopIteration:
+                continue
+            d = pickle.dumps(it, proto)
+            it = pickle.loads(d)
+            del data[drop]
+            self.assertEqual(list(it), list(reversed(data)))
+
+    def test_reverseitemiterator_pickling(self):
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            data = {1:"a", 2:"b", 3:"c"}
+            # dictviews aren't picklable, only their iterators
+            itorg = reversed(data.items())
+            d = pickle.dumps(itorg, proto)
+            it = pickle.loads(d)
+            # note that the type of the unpickled iterator
+            # is not necessarily the same as the original.  It is
+            # merely an object supporting the iterator protocol, yielding
+            # the same objects as the original one.
+            # self.assertEqual(type(itorg), type(it))
+            self.assertIsInstance(it, collections.abc.Iterator)
+            self.assertEqual(dict(it), data)
+
+            it = pickle.loads(d)
+            drop = next(it)
+            d = pickle.dumps(it, proto)
+            it = pickle.loads(d)
+            del data[drop[0]]
+            self.assertEqual(dict(it), data)
+
+    def test_reversevaluesiterator_pickling(self):
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            data = {1:"a", 2:"b", 3:"c"}
+            # data.values() isn't picklable, only its iterator
+            it = reversed(data.values())
+            d = pickle.dumps(it, proto)
+            it = pickle.loads(d)
+            self.assertEqual(list(it), list(reversed(data.values())))
+
+            it = pickle.loads(d)
+            drop = next(it)
+            d = pickle.dumps(it, proto)
+            it = pickle.loads(d)
+            values = list(it) + [drop]
+            self.assertEqual(sorted(values), sorted(data.values()))
+
+    def test_instance_dict_getattr_str_subclass(self):
+        class Foo:
+            def __init__(self, msg):
+                self.msg = msg
+        f = Foo('123')
+        class _str(str):
+            pass
+        self.assertEqual(f.msg, getattr(f, _str('msg')))
+        self.assertEqual(f.msg, f.__dict__[_str('msg')])
+
+    def test_object_set_item_single_instance_non_str_key(self):
+        class Foo: pass
+        f = Foo()
+        f.__dict__[1] = 1
+        f.a = 'a'
+        self.assertEqual(f.__dict__, {1:1, 'a':'a'})
+
+    def check_reentrant_insertion(self, mutate):
+        # This object will trigger mutation of the dict when replaced
+        # by another value.  Note this relies on refcounting: the test
+        # won't achieve its purpose on fully-GCed Python implementations.
+        class Mutating:
+            def __del__(self):
+                mutate(d)
+
+        d = {k: Mutating() for k in 'abcdefghijklmnopqr'}
+        for k in list(d):
+            d[k] = k
+
+    def test_reentrant_insertion(self):
+        # Reentrant insertion shouldn't crash (see issue #22653)
+        def mutate(d):
+            d['b'] = 5
+        self.check_reentrant_insertion(mutate)
+
+        def mutate(d):
+            d.update(self.__dict__)
+            d.clear()
+        self.check_reentrant_insertion(mutate)
+
+        def mutate(d):
+            while d:
+                d.popitem()
+        self.check_reentrant_insertion(mutate)
+
+    def test_merge_and_mutate(self):
+        class X:
+            def __hash__(self):
+                return 0
+
+            def __eq__(self, o):
+                other.clear()
+                return False
+
+        l = [(i,0) for i in range(1, 1337)]
+        other = dict(l)
+        other[X()] = 0
+        d = {X(): 0, 1: 1}
+        self.assertRaises(RuntimeError, d.update, other)
+
+    def test_free_after_iterating(self):
+        support.check_free_after_iterating(self, iter, dict)
+        support.check_free_after_iterating(self, lambda d: iter(d.keys()), dict)
+        support.check_free_after_iterating(self, lambda d: iter(d.values()), dict)
+        support.check_free_after_iterating(self, lambda d: iter(d.items()), dict)
+
+    def test_equal_operator_modifying_operand(self):
+        # test fix for seg fault reported in issue 27945 part 3.
+        class X():
+            def __del__(self):
+                dict_b.clear()
+
+            def __eq__(self, other):
+                dict_a.clear()
+                return True
+
+            def __hash__(self):
+                return 13
+
+        dict_a = {X(): 0}
+        dict_b = {X(): X()}
+        self.assertTrue(dict_a == dict_b)
+
+    def test_fromkeys_operator_modifying_dict_operand(self):
+        # test fix for seg fault reported in issue 27945 part 4a.
+        class X(int):
+            def __hash__(self):
+                return 13
+
+            def __eq__(self, other):
+                if len(d) > 1:
+                    d.clear()
+                return False
+
+        d = {}  # this is required to exist so that d can be constructed!
+        d = {X(1): 1, X(2): 2}
+        try:
+            dict.fromkeys(d)  # shouldn't crash
+        except RuntimeError:  # implementation defined
+            pass
+
+    def test_fromkeys_operator_modifying_set_operand(self):
+        # test fix for seg fault reported in issue 27945 part 4b.
+        class X(int):
+            def __hash__(self):
+                return 13
+
+            def __eq__(self, other):
+                if len(d) > 1:
+                    d.clear()
+                return False
+
+        d = {}  # this is required to exist so that d can be constructed!
+        d = {X(1), X(2)}
+        try:
+            dict.fromkeys(d)  # shouldn't crash
+        except RuntimeError:  # implementation defined
+            pass
+
+    def test_dictitems_contains_use_after_free(self):
+        class X:
+            def __eq__(self, other):
+                d.clear()
+                return NotImplemented
+
+        d = {0: set()}
+        (0, X()) in d.items()
+
+    def test_init_use_after_free(self):
+        class X:
+            def __hash__(self):
+                pair[:] = []
+                return 13
+
+        pair = [X(), 123]
+        dict([pair])
+
+    def test_oob_indexing_dictiter_iternextitem(self):
+        class X(int):
+            def __del__(self):
+                d.clear()
+
+        d = {i: X(i) for i in range(8)}
+
+        def iter_and_mutate():
+            for result in d.items():
+                if result[0] == 2:
+                    d[2] = None # free d[2] --> X(2).__del__ was called
+
+        self.assertRaises(RuntimeError, iter_and_mutate)
+
+    def test_reversed(self):
+        d = {"a": 1, "b": 2, "foo": 0, "c": 3, "d": 4}
+        del d["foo"]
+        r = reversed(d)
+        self.assertEqual(list(r), list('dcba'))
+        self.assertRaises(StopIteration, next, r)
+
+    def test_dict_copy_order(self):
+        # bpo-34320
+        od = collections.OrderedDict([('a', 1), ('b', 2)])
+        od.move_to_end('a')
+        expected = list(od.items())
+
+        copy = dict(od)
+        self.assertEqual(list(copy.items()), expected)
+
+        # dict subclass doesn't override __iter__
+        class CustomDict(dict):
+            pass
+
+        pairs = [('a', 1), ('b', 2), ('c', 3)]
+
+        d = CustomDict(pairs)
+        self.assertEqual(pairs, list(dict(d).items()))
+
+        class CustomReversedDict(dict):
+            def keys(self):
+                return reversed(list(dict.keys(self)))
+
+            __iter__ = keys
+
+            def items(self):
+                return reversed(dict.items(self))
+
+        d = CustomReversedDict(pairs)
+        self.assertEqual(pairs[::-1], list(dict(d).items()))
+
+
+class CAPITest(unittest.TestCase):
+
+    # Test _PyDict_GetItem_KnownHash()
+    @support.cpython_only
+    def test_getitem_knownhash(self):
+        from _testcapi import dict_getitem_knownhash
+
+        d = {'x': 1, 'y': 2, 'z': 3}
+        self.assertEqual(dict_getitem_knownhash(d, 'x', hash('x')), 1)
+        self.assertEqual(dict_getitem_knownhash(d, 'y', hash('y')), 2)
+        self.assertEqual(dict_getitem_knownhash(d, 'z', hash('z')), 3)
+
+        # not a dict
+        self.assertRaises(SystemError, dict_getitem_knownhash, [], 1, hash(1))
+        # key does not exist
+        self.assertRaises(KeyError, dict_getitem_knownhash, {}, 1, hash(1))
+
+        class Exc(Exception): pass
+        class BadEq:
+            def __eq__(self, other):
+                raise Exc
+            def __hash__(self):
+                return 7
+
+        k1, k2 = BadEq(), BadEq()
+        d = {k1: 1}
+        self.assertEqual(dict_getitem_knownhash(d, k1, hash(k1)), 1)
+        self.assertRaises(Exc, dict_getitem_knownhash, d, k2, hash(k2))
+
+
+from test import mapping_tests
+
+class GeneralMappingTests(mapping_tests.BasicTestMappingProtocol):
+    type2test = dict
+
+class Dict(dict):
+    pass
+
+class SubclassMappingTests(mapping_tests.BasicTestMappingProtocol):
+    type2test = Dict
+
+
+if __name__ == "__main__":
+    unittest.main()