Issue #25616: Tests for OrderedDict are extracted from test_collections

into separate file test_ordered_dict.

3 files changed, 318 insertions, 307 deletions

diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index 66db90f..0882bac 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -1,16 +1,19 @@
 """Unit tests for collections.py."""
 
-import unittest, doctest, operator
-from test.support import TESTFN, forget, unlink
-import inspect
-from test import support
-from collections import namedtuple, Counter, OrderedDict, _count_elements
-from test import mapping_tests
-import pickle, copy
-from random import randrange, shuffle
+import collections
+import copy
+import doctest
 import keyword
+import operator
+import pickle
+from random import choice, randrange
 import re
+import string
 import sys
+from test import support
+import unittest
+
+from collections import namedtuple, Counter, OrderedDict, _count_elements
 from collections import UserDict
 from collections import ChainMap
 from collections.abc import Hashable, Iterable, Iterator
@@ -281,8 +284,7 @@ class TestNamedTuple(unittest.TestCase):
 
         # n = 5000
         n = 254 # SyntaxError: more than 255 arguments:
-        import string, random
-        names = list(set(''.join([random.choice(string.ascii_letters)
+        names = list(set(''.join([choice(string.ascii_letters)
                                   for j in range(10)]) for i in range(n)))
         n = len(names)
         Big = namedtuple('Big', names)
@@ -1281,309 +1283,13 @@ class TestCounter(unittest.TestCase):
 
 
 ################################################################################
-### OrderedDict
-################################################################################
-
-class TestOrderedDict(unittest.TestCase):
-
-    def test_init(self):
-        with self.assertRaises(TypeError):
-            OrderedDict([('a', 1), ('b', 2)], None)                                 # too many args
-        pairs = [('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5)]
-        self.assertEqual(sorted(OrderedDict(dict(pairs)).items()), pairs)           # dict input
-        self.assertEqual(sorted(OrderedDict(**dict(pairs)).items()), pairs)         # kwds input
-        self.assertEqual(list(OrderedDict(pairs).items()), pairs)                   # pairs input
-        self.assertEqual(list(OrderedDict([('a', 1), ('b', 2), ('c', 9), ('d', 4)],
-                                          c=3, e=5).items()), pairs)                # mixed input
-
-        # make sure no positional args conflict with possible kwdargs
-        self.assertEqual(list(OrderedDict(self=42).items()), [('self', 42)])
-        self.assertEqual(list(OrderedDict(other=42).items()), [('other', 42)])
-        self.assertRaises(TypeError, OrderedDict, 42)
-        self.assertRaises(TypeError, OrderedDict, (), ())
-        self.assertRaises(TypeError, OrderedDict.__init__)
-
-        # Make sure that direct calls to __init__ do not clear previous contents
-        d = OrderedDict([('a', 1), ('b', 2), ('c', 3), ('d', 44), ('e', 55)])
-        d.__init__([('e', 5), ('f', 6)], g=7, d=4)
-        self.assertEqual(list(d.items()),
-            [('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5), ('f', 6), ('g', 7)])
-
-    def test_update(self):
-        with self.assertRaises(TypeError):
-            OrderedDict().update([('a', 1), ('b', 2)], None)                        # too many args
-        pairs = [('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5)]
-        od = OrderedDict()
-        od.update(dict(pairs))
-        self.assertEqual(sorted(od.items()), pairs)                                 # dict input
-        od = OrderedDict()
-        od.update(**dict(pairs))
-        self.assertEqual(sorted(od.items()), pairs)                                 # kwds input
-        od = OrderedDict()
-        od.update(pairs)
-        self.assertEqual(list(od.items()), pairs)                                   # pairs input
-        od = OrderedDict()
-        od.update([('a', 1), ('b', 2), ('c', 9), ('d', 4)], c=3, e=5)
-        self.assertEqual(list(od.items()), pairs)                                   # mixed input
-
-        # Issue 9137: Named argument called 'other' or 'self'
-        # shouldn't be treated specially.
-        od = OrderedDict()
-        od.update(self=23)
-        self.assertEqual(list(od.items()), [('self', 23)])
-        od = OrderedDict()
-        od.update(other={})
-        self.assertEqual(list(od.items()), [('other', {})])
-        od = OrderedDict()
-        od.update(red=5, blue=6, other=7, self=8)
-        self.assertEqual(sorted(list(od.items())),
-                         [('blue', 6), ('other', 7), ('red', 5), ('self', 8)])
-
-        # Make sure that direct calls to update do not clear previous contents
-        # add that updates items are not moved to the end
-        d = OrderedDict([('a', 1), ('b', 2), ('c', 3), ('d', 44), ('e', 55)])
-        d.update([('e', 5), ('f', 6)], g=7, d=4)
-        self.assertEqual(list(d.items()),
-            [('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5), ('f', 6), ('g', 7)])
-
-        self.assertRaises(TypeError, OrderedDict().update, 42)
-        self.assertRaises(TypeError, OrderedDict().update, (), ())
-        self.assertRaises(TypeError, OrderedDict.update)
-
-    def test_abc(self):
-        self.assertIsInstance(OrderedDict(), MutableMapping)
-        self.assertTrue(issubclass(OrderedDict, MutableMapping))
-
-    def test_clear(self):
-        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
-        shuffle(pairs)
-        od = OrderedDict(pairs)
-        self.assertEqual(len(od), len(pairs))
-        od.clear()
-        self.assertEqual(len(od), 0)
-
-    def test_delitem(self):
-        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
-        od = OrderedDict(pairs)
-        del od['a']
-        self.assertNotIn('a', od)
-        with self.assertRaises(KeyError):
-            del od['a']
-        self.assertEqual(list(od.items()), pairs[:2] + pairs[3:])
-
-    def test_setitem(self):
-        od = OrderedDict([('d', 1), ('b', 2), ('c', 3), ('a', 4), ('e', 5)])
-        od['c'] = 10           # existing element
-        od['f'] = 20           # new element
-        self.assertEqual(list(od.items()),
-                         [('d', 1), ('b', 2), ('c', 10), ('a', 4), ('e', 5), ('f', 20)])
-
-    def test_iterators(self):
-        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
-        shuffle(pairs)
-        od = OrderedDict(pairs)
-        self.assertEqual(list(od), [t[0] for t in pairs])
-        self.assertEqual(list(od.keys()), [t[0] for t in pairs])
-        self.assertEqual(list(od.values()), [t[1] for t in pairs])
-        self.assertEqual(list(od.items()), pairs)
-        self.assertEqual(list(reversed(od)),
-                         [t[0] for t in reversed(pairs)])
-
-    def test_popitem(self):
-        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
-        shuffle(pairs)
-        od = OrderedDict(pairs)
-        while pairs:
-            self.assertEqual(od.popitem(), pairs.pop())
-        with self.assertRaises(KeyError):
-            od.popitem()
-        self.assertEqual(len(od), 0)
-
-    def test_pop(self):
-        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
-        shuffle(pairs)
-        od = OrderedDict(pairs)
-        shuffle(pairs)
-        while pairs:
-            k, v = pairs.pop()
-            self.assertEqual(od.pop(k), v)
-        with self.assertRaises(KeyError):
-            od.pop('xyz')
-        self.assertEqual(len(od), 0)
-        self.assertEqual(od.pop(k, 12345), 12345)
-
-        # make sure pop still works when __missing__ is defined
-        class Missing(OrderedDict):
-            def __missing__(self, key):
-                return 0
-        m = Missing(a=1)
-        self.assertEqual(m.pop('b', 5), 5)
-        self.assertEqual(m.pop('a', 6), 1)
-        self.assertEqual(m.pop('a', 6), 6)
-        with self.assertRaises(KeyError):
-            m.pop('a')
-
-    def test_equality(self):
-        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
-        shuffle(pairs)
-        od1 = OrderedDict(pairs)
-        od2 = OrderedDict(pairs)
-        self.assertEqual(od1, od2)          # same order implies equality
-        pairs = pairs[2:] + pairs[:2]
-        od2 = OrderedDict(pairs)
-        self.assertNotEqual(od1, od2)       # different order implies inequality
-        # comparison to regular dict is not order sensitive
-        self.assertEqual(od1, dict(od2))
-        self.assertEqual(dict(od2), od1)
-        # different length implied inequality
-        self.assertNotEqual(od1, OrderedDict(pairs[:-1]))
-
-    def test_copying(self):
-        # Check that ordered dicts are copyable, deepcopyable, picklable,
-        # and have a repr/eval round-trip
-        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
-        od = OrderedDict(pairs)
-        def check(dup):
-            msg = "\ncopy: %s\nod: %s" % (dup, od)
-            self.assertIsNot(dup, od, msg)
-            self.assertEqual(dup, od)
-        check(od.copy())
-        check(copy.copy(od))
-        check(copy.deepcopy(od))
-        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
-            with self.subTest(proto=proto):
-                check(pickle.loads(pickle.dumps(od, proto)))
-        check(eval(repr(od)))
-        update_test = OrderedDict()
-        update_test.update(od)
-        check(update_test)
-        check(OrderedDict(od))
-
-    def test_yaml_linkage(self):
-        # Verify that __reduce__ is setup in a way that supports PyYAML's dump() feature.
-        # In yaml, lists are native but tuples are not.
-        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
-        od = OrderedDict(pairs)
-        # yaml.dump(od) -->
-        # '!!python/object/apply:__main__.OrderedDict\n- - [a, 1]\n  - [b, 2]\n'
-        self.assertTrue(all(type(pair)==list for pair in od.__reduce__()[1]))
-
-    def test_reduce_not_too_fat(self):
-        # do not save instance dictionary if not needed
-        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
-        od = OrderedDict(pairs)
-        self.assertIsNone(od.__reduce__()[2])
-        od.x = 10
-        self.assertIsNotNone(od.__reduce__()[2])
-
-    def test_pickle_recursive(self):
-        od = OrderedDict()
-        od[1] = od
-        for proto in range(-1, pickle.HIGHEST_PROTOCOL + 1):
-            dup = pickle.loads(pickle.dumps(od, proto))
-            self.assertIsNot(dup, od)
-            self.assertEqual(list(dup.keys()), [1])
-            self.assertIs(dup[1], dup)
-
-    def test_repr(self):
-        od = OrderedDict([('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)])
-        self.assertEqual(repr(od),
-            "OrderedDict([('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)])")
-        self.assertEqual(eval(repr(od)), od)
-        self.assertEqual(repr(OrderedDict()), "OrderedDict()")
-
-    def test_repr_recursive(self):
-        # See issue #9826
-        od = OrderedDict.fromkeys('abc')
-        od['x'] = od
-        self.assertEqual(repr(od),
-            "OrderedDict([('a', None), ('b', None), ('c', None), ('x', ...)])")
-
-    def test_setdefault(self):
-        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
-        shuffle(pairs)
-        od = OrderedDict(pairs)
-        pair_order = list(od.items())
-        self.assertEqual(od.setdefault('a', 10), 3)
-        # make sure order didn't change
-        self.assertEqual(list(od.items()), pair_order)
-        self.assertEqual(od.setdefault('x', 10), 10)
-        # make sure 'x' is added to the end
-        self.assertEqual(list(od.items())[-1], ('x', 10))
-
-        # make sure setdefault still works when __missing__ is defined
-        class Missing(OrderedDict):
-            def __missing__(self, key):
-                return 0
-        self.assertEqual(Missing().setdefault(5, 9), 9)
-
-    def test_reinsert(self):
-        # Given insert a, insert b, delete a, re-insert a,
-        # verify that a is now later than b.
-        od = OrderedDict()
-        od['a'] = 1
-        od['b'] = 2
-        del od['a']
-        od['a'] = 1
-        self.assertEqual(list(od.items()), [('b', 2), ('a', 1)])
-
-    def test_move_to_end(self):
-        od = OrderedDict.fromkeys('abcde')
-        self.assertEqual(list(od), list('abcde'))
-        od.move_to_end('c')
-        self.assertEqual(list(od), list('abdec'))
-        od.move_to_end('c', 0)
-        self.assertEqual(list(od), list('cabde'))
-        od.move_to_end('c', 0)
-        self.assertEqual(list(od), list('cabde'))
-        od.move_to_end('e')
-        self.assertEqual(list(od), list('cabde'))
-        with self.assertRaises(KeyError):
-            od.move_to_end('x')
-
-    def test_sizeof(self):
-        # Wimpy test: Just verify the reported size is larger than a regular dict
-        d = dict(a=1)
-        od = OrderedDict(**d)
-        self.assertGreater(sys.getsizeof(od), sys.getsizeof(d))
-
-    def test_override_update(self):
-        # Verify that subclasses can override update() without breaking __init__()
-        class MyOD(OrderedDict):
-            def update(self, *args, **kwds):
-                raise Exception()
-        items = [('a', 1), ('c', 3), ('b', 2)]
-        self.assertEqual(list(MyOD(items).items()), items)
-
-class GeneralMappingTests(mapping_tests.BasicTestMappingProtocol):
-    type2test = OrderedDict
-
-    def test_popitem(self):
-        d = self._empty_mapping()
-        self.assertRaises(KeyError, d.popitem)
-
-class MyOrderedDict(OrderedDict):
-    pass
-
-class SubclassMappingTests(mapping_tests.BasicTestMappingProtocol):
-    type2test = MyOrderedDict
-
-    def test_popitem(self):
-        d = self._empty_mapping()
-        self.assertRaises(KeyError, d.popitem)
-
-
-################################################################################
 ### Run tests
 ################################################################################
 
-import doctest, collections
-
 def test_main(verbose=None):
     NamedTupleDocs = doctest.DocTestSuite(module=collections)
     test_classes = [TestNamedTuple, NamedTupleDocs, TestOneTrickPonyABCs,
-                    TestCollectionABCs, TestCounter, TestChainMap,
-                    TestOrderedDict, GeneralMappingTests, SubclassMappingTests]
+                    TestCollectionABCs, TestCounter, TestChainMap]
     support.run_unittest(*test_classes)
     support.run_doctest(collections, verbose)
 
diff --git a/Lib/test/test_ordered_dict.py b/Lib/test/test_ordered_dict.py
new file mode 100644
index 0000000..6d3e309
--- /dev/null
+++ b/Lib/test/test_ordered_dict.py
@@ -0,0 +1,302 @@
+import contextlib
+import copy
+import pickle
+from random import shuffle
+import sys
+import unittest
+from collections import OrderedDict
+from collections.abc import MutableMapping
+from test import mapping_tests, support
+
+
+class TestOrderedDict(unittest.TestCase):
+
+    def test_init(self):
+        with self.assertRaises(TypeError):
+            OrderedDict([('a', 1), ('b', 2)], None)                                 # too many args
+        pairs = [('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5)]
+        self.assertEqual(sorted(OrderedDict(dict(pairs)).items()), pairs)           # dict input
+        self.assertEqual(sorted(OrderedDict(**dict(pairs)).items()), pairs)         # kwds input
+        self.assertEqual(list(OrderedDict(pairs).items()), pairs)                   # pairs input
+        self.assertEqual(list(OrderedDict([('a', 1), ('b', 2), ('c', 9), ('d', 4)],
+                                          c=3, e=5).items()), pairs)                # mixed input
+
+        # make sure no positional args conflict with possible kwdargs
+        self.assertEqual(list(OrderedDict(self=42).items()), [('self', 42)])
+        self.assertEqual(list(OrderedDict(other=42).items()), [('other', 42)])
+        self.assertRaises(TypeError, OrderedDict, 42)
+        self.assertRaises(TypeError, OrderedDict, (), ())
+        self.assertRaises(TypeError, OrderedDict.__init__)
+
+        # Make sure that direct calls to __init__ do not clear previous contents
+        d = OrderedDict([('a', 1), ('b', 2), ('c', 3), ('d', 44), ('e', 55)])
+        d.__init__([('e', 5), ('f', 6)], g=7, d=4)
+        self.assertEqual(list(d.items()),
+            [('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5), ('f', 6), ('g', 7)])
+
+    def test_update(self):
+        with self.assertRaises(TypeError):
+            OrderedDict().update([('a', 1), ('b', 2)], None)                        # too many args
+        pairs = [('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5)]
+        od = OrderedDict()
+        od.update(dict(pairs))
+        self.assertEqual(sorted(od.items()), pairs)                                 # dict input
+        od = OrderedDict()
+        od.update(**dict(pairs))
+        self.assertEqual(sorted(od.items()), pairs)                                 # kwds input
+        od = OrderedDict()
+        od.update(pairs)
+        self.assertEqual(list(od.items()), pairs)                                   # pairs input
+        od = OrderedDict()
+        od.update([('a', 1), ('b', 2), ('c', 9), ('d', 4)], c=3, e=5)
+        self.assertEqual(list(od.items()), pairs)                                   # mixed input
+
+        # Issue 9137: Named argument called 'other' or 'self'
+        # shouldn't be treated specially.
+        od = OrderedDict()
+        od.update(self=23)
+        self.assertEqual(list(od.items()), [('self', 23)])
+        od = OrderedDict()
+        od.update(other={})
+        self.assertEqual(list(od.items()), [('other', {})])
+        od = OrderedDict()
+        od.update(red=5, blue=6, other=7, self=8)
+        self.assertEqual(sorted(list(od.items())),
+                         [('blue', 6), ('other', 7), ('red', 5), ('self', 8)])
+
+        # Make sure that direct calls to update do not clear previous contents
+        # add that updates items are not moved to the end
+        d = OrderedDict([('a', 1), ('b', 2), ('c', 3), ('d', 44), ('e', 55)])
+        d.update([('e', 5), ('f', 6)], g=7, d=4)
+        self.assertEqual(list(d.items()),
+            [('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5), ('f', 6), ('g', 7)])
+
+        self.assertRaises(TypeError, OrderedDict().update, 42)
+        self.assertRaises(TypeError, OrderedDict().update, (), ())
+        self.assertRaises(TypeError, OrderedDict.update)
+
+    def test_abc(self):
+        self.assertIsInstance(OrderedDict(), MutableMapping)
+        self.assertTrue(issubclass(OrderedDict, MutableMapping))
+
+    def test_clear(self):
+        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
+        shuffle(pairs)
+        od = OrderedDict(pairs)
+        self.assertEqual(len(od), len(pairs))
+        od.clear()
+        self.assertEqual(len(od), 0)
+
+    def test_delitem(self):
+        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
+        od = OrderedDict(pairs)
+        del od['a']
+        self.assertNotIn('a', od)
+        with self.assertRaises(KeyError):
+            del od['a']
+        self.assertEqual(list(od.items()), pairs[:2] + pairs[3:])
+
+    def test_setitem(self):
+        od = OrderedDict([('d', 1), ('b', 2), ('c', 3), ('a', 4), ('e', 5)])
+        od['c'] = 10           # existing element
+        od['f'] = 20           # new element
+        self.assertEqual(list(od.items()),
+                         [('d', 1), ('b', 2), ('c', 10), ('a', 4), ('e', 5), ('f', 20)])
+
+    def test_iterators(self):
+        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
+        shuffle(pairs)
+        od = OrderedDict(pairs)
+        self.assertEqual(list(od), [t[0] for t in pairs])
+        self.assertEqual(list(od.keys()), [t[0] for t in pairs])
+        self.assertEqual(list(od.values()), [t[1] for t in pairs])
+        self.assertEqual(list(od.items()), pairs)
+        self.assertEqual(list(reversed(od)),
+                         [t[0] for t in reversed(pairs)])
+
+    def test_popitem(self):
+        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
+        shuffle(pairs)
+        od = OrderedDict(pairs)
+        while pairs:
+            self.assertEqual(od.popitem(), pairs.pop())
+        with self.assertRaises(KeyError):
+            od.popitem()
+        self.assertEqual(len(od), 0)
+
+    def test_pop(self):
+        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
+        shuffle(pairs)
+        od = OrderedDict(pairs)
+        shuffle(pairs)
+        while pairs:
+            k, v = pairs.pop()
+            self.assertEqual(od.pop(k), v)
+        with self.assertRaises(KeyError):
+            od.pop('xyz')
+        self.assertEqual(len(od), 0)
+        self.assertEqual(od.pop(k, 12345), 12345)
+
+        # make sure pop still works when __missing__ is defined
+        class Missing(OrderedDict):
+            def __missing__(self, key):
+                return 0
+        m = Missing(a=1)
+        self.assertEqual(m.pop('b', 5), 5)
+        self.assertEqual(m.pop('a', 6), 1)
+        self.assertEqual(m.pop('a', 6), 6)
+        with self.assertRaises(KeyError):
+            m.pop('a')
+
+    def test_equality(self):
+        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
+        shuffle(pairs)
+        od1 = OrderedDict(pairs)
+        od2 = OrderedDict(pairs)
+        self.assertEqual(od1, od2)          # same order implies equality
+        pairs = pairs[2:] + pairs[:2]
+        od2 = OrderedDict(pairs)
+        self.assertNotEqual(od1, od2)       # different order implies inequality
+        # comparison to regular dict is not order sensitive
+        self.assertEqual(od1, dict(od2))
+        self.assertEqual(dict(od2), od1)
+        # different length implied inequality
+        self.assertNotEqual(od1, OrderedDict(pairs[:-1]))
+
+    def test_copying(self):
+        # Check that ordered dicts are copyable, deepcopyable, picklable,
+        # and have a repr/eval round-trip
+        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
+        od = OrderedDict(pairs)
+        def check(dup):
+            msg = "\ncopy: %s\nod: %s" % (dup, od)
+            self.assertIsNot(dup, od, msg)
+            self.assertEqual(dup, od)
+        check(od.copy())
+        check(copy.copy(od))
+        check(copy.deepcopy(od))
+        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+            with self.subTest(proto=proto):
+                check(pickle.loads(pickle.dumps(od, proto)))
+        check(eval(repr(od)))
+        update_test = OrderedDict()
+        update_test.update(od)
+        check(update_test)
+        check(OrderedDict(od))
+
+    def test_yaml_linkage(self):
+        # Verify that __reduce__ is setup in a way that supports PyYAML's dump() feature.
+        # In yaml, lists are native but tuples are not.
+        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
+        od = OrderedDict(pairs)
+        # yaml.dump(od) -->
+        # '!!python/object/apply:__main__.OrderedDict\n- - [a, 1]\n  - [b, 2]\n'
+        self.assertTrue(all(type(pair)==list for pair in od.__reduce__()[1]))
+
+    def test_reduce_not_too_fat(self):
+        # do not save instance dictionary if not needed
+        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
+        od = OrderedDict(pairs)
+        self.assertIsNone(od.__reduce__()[2])
+        od.x = 10
+        self.assertIsNotNone(od.__reduce__()[2])
+
+    def test_pickle_recursive(self):
+        od = OrderedDict()
+        od[1] = od
+        for proto in range(-1, pickle.HIGHEST_PROTOCOL + 1):
+            dup = pickle.loads(pickle.dumps(od, proto))
+            self.assertIsNot(dup, od)
+            self.assertEqual(list(dup.keys()), [1])
+            self.assertIs(dup[1], dup)
+
+    def test_repr(self):
+        od = OrderedDict([('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)])
+        self.assertEqual(repr(od),
+            "OrderedDict([('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)])")
+        self.assertEqual(eval(repr(od)), od)
+        self.assertEqual(repr(OrderedDict()), "OrderedDict()")
+
+    def test_repr_recursive(self):
+        # See issue #9826
+        od = OrderedDict.fromkeys('abc')
+        od['x'] = od
+        self.assertEqual(repr(od),
+            "OrderedDict([('a', None), ('b', None), ('c', None), ('x', ...)])")
+
+    def test_setdefault(self):
+        pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
+        shuffle(pairs)
+        od = OrderedDict(pairs)
+        pair_order = list(od.items())
+        self.assertEqual(od.setdefault('a', 10), 3)
+        # make sure order didn't change
+        self.assertEqual(list(od.items()), pair_order)
+        self.assertEqual(od.setdefault('x', 10), 10)
+        # make sure 'x' is added to the end
+        self.assertEqual(list(od.items())[-1], ('x', 10))
+
+        # make sure setdefault still works when __missing__ is defined
+        class Missing(OrderedDict):
+            def __missing__(self, key):
+                return 0
+        self.assertEqual(Missing().setdefault(5, 9), 9)
+
+    def test_reinsert(self):
+        # Given insert a, insert b, delete a, re-insert a,
+        # verify that a is now later than b.
+        od = OrderedDict()
+        od['a'] = 1
+        od['b'] = 2
+        del od['a']
+        od['a'] = 1
+        self.assertEqual(list(od.items()), [('b', 2), ('a', 1)])
+
+    def test_move_to_end(self):
+        od = OrderedDict.fromkeys('abcde')
+        self.assertEqual(list(od), list('abcde'))
+        od.move_to_end('c')
+        self.assertEqual(list(od), list('abdec'))
+        od.move_to_end('c', 0)
+        self.assertEqual(list(od), list('cabde'))
+        od.move_to_end('c', 0)
+        self.assertEqual(list(od), list('cabde'))
+        od.move_to_end('e')
+        self.assertEqual(list(od), list('cabde'))
+        with self.assertRaises(KeyError):
+            od.move_to_end('x')
+
+    def test_sizeof(self):
+        # Wimpy test: Just verify the reported size is larger than a regular dict
+        d = dict(a=1)
+        od = OrderedDict(**d)
+        self.assertGreater(sys.getsizeof(od), sys.getsizeof(d))
+
+    def test_override_update(self):
+        # Verify that subclasses can override update() without breaking __init__()
+        class MyOD(OrderedDict):
+            def update(self, *args, **kwds):
+                raise Exception()
+        items = [('a', 1), ('c', 3), ('b', 2)]
+        self.assertEqual(list(MyOD(items).items()), items)
+
+class GeneralMappingTests(mapping_tests.BasicTestMappingProtocol):
+    type2test = OrderedDict
+
+    def test_popitem(self):
+        d = self._empty_mapping()
+        self.assertRaises(KeyError, d.popitem)
+
+class MyOrderedDict(OrderedDict):
+    pass
+
+class SubclassMappingTests(mapping_tests.BasicTestMappingProtocol):
+    type2test = MyOrderedDict
+
+    def test_popitem(self):
+        d = self._empty_mapping()
+        self.assertRaises(KeyError, d.popitem)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/Misc/NEWS b/Misc/NEWS
index bae6698..fa365cc 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -694,6 +694,9 @@ IDLE
 Tests
 -----
 
+- Issue #25616: Tests for OrderedDict are extracted from test_collections
+  into separate file test_ordered_dict.
+
 - Issue #25099: Make test_compileall not fail when an entry on sys.path cannot
   be written to (commonly seen in administrative installs on Windows).