support for enum34 backport library for enums in older python versions

.gitignore

@@ -4,7 +4,7 @@
 *.so
 
 # Packages
-*.egg
+*.egg[s]
 *.egg-info
 dist
 build

.travis.yml

@@ -14,8 +14,9 @@ dist: trusty
 
 # Installation installs dependencies
 install:
-  - pip install pytz
-  - pip install .
+  - pip install --user pytz
+  - pip install --user enum34;python_version<"3.4"
+  - pip install --user .
 
 script:
   - if [[ $TRAVIS_PYTHON_VERSION != pypy* ]]; then cd tests && python -E -Wall -tt -bb test_serpent.py; fi

serpent.py

@@ -76,11 +76,16 @@
 import collections
 if sys.version_info >= (3, 4):
     from collections.abc import KeysView, ValuesView, ItemsView
+    import enum
 else:
     from collections import KeysView, ValuesView, ItemsView
+    try:
+        import enum
+    except ImportError:
+        enum = None
 
 
-__version__ = "1.25"
+__version__ = "1.26"
 __all__ = ["dump", "dumps", "load", "loads", "register_class", "unregister_class", "tobytes"]
 
 can_use_set_literals = sys.version_info >= (3, 2)  # check if we can use set literals
@@ -161,9 +166,7 @@ def _reset_special_classes_registry():
     _special_classes_registry[ItemsView] = _ser_DictView
     if sys.version_info >= (2, 7):
         _special_classes_registry[collections.OrderedDict] = _ser_OrderedDict
-    if sys.version_info >= (3, 4):
-        import enum
-
+    if enum is not None:
         def _ser_Enum(obj, serializer, outputstream, indentlevel):
             serializer._serialize(obj.value, outputstream, indentlevel)
         _special_classes_registry[enum.Enum] = _ser_Enum
@@ -457,8 +460,7 @@ def ser_builtins_list(self, list_obj, out, level):
 
     def _check_hashable_type(self, t):
         if t not in (bool, bytes, str, tuple) and not issubclass(t, numbers.Number):
-            if sys.version_info >= (3, 4):
-                import enum
+            if enum is not None:
                 if issubclass(t, enum.Enum):
                     return
             elif sys.version_info < (3, 0) and t is unicode:

setup.py

@@ -173,5 +173,5 @@ def __init__(self):
         "Programming Language :: Python :: 3.7",
         "Topic :: Software Development"
     ],
-
+    tests_require=['enum34; python_version < "3.4"']
 )

tests/test_serpent.py

@@ -21,6 +21,7 @@
 import time
 import types
 import collections
+import enum
 if sys.version_info >= (3, 4):
     from collections.abc import KeysView, ValuesView, ItemsView
 else:
@@ -617,19 +618,23 @@ def test_class_hashable_set_element_check(self):
             serpent.dumps({1, 2, 3, pp})     # can only serialize simple typles as set elements (hashable)
         self.assertTrue("hashable type" in str(x.exception))
 
-    @unittest.skipIf(sys.version_info < (3, 4), reason="python 3.4 introduced enums")
     def test_enum_hashable(self):
-        import enum
         class Color(enum.Enum):
             RED = 1
             GREEN = 2
             BLUE = 3
         data = serpent.dumps({"abc", Color.RED, Color.GREEN, Color.BLUE})
         orig = serpent.loads(data)
-        self.assertEqual({"abc", 1, 2, 3}, orig)
+        if sys.version_info < (3, 4):
+            self.assertEqual([1, 2, 3, u"abc"], sorted(orig))
+        else:
+            self.assertEqual({"abc", 1, 2, 3}, orig)
         data = serpent.dumps({"abc": 1, Color.RED: 1, Color.GREEN: 1, Color.BLUE: 1})
         orig = serpent.loads(data)
-        self.assertEqual({"abc": 1, 1: 1, 2: 1, 3: 1}, orig)
+        if sys.version_info < (3, 4):
+            self.assertEqual({u"abc": 1, 1: 1, 2: 1, 3: 1}, orig)
+        else:
+            self.assertEqual({"abc": 1, 1: 1, 2: 1, 3: 1}, orig)
 
     def test_array(self):
         ser = serpent.dumps(array.array('u', unicode("unicode")))
@@ -714,16 +719,19 @@ def test_float_precision(self):
         v = serpent.loads(serpent.dumps((-98765432123456.12345678987656e+44 -665544332211.9998877665544e+33j)))
         self.assertEqual((-98765432123456.12345678987656e+44 -665544332211.9998877665544e+33j), v)
 
-    @unittest.skipIf(sys.version_info < (3, 4), "needs python 3.4 to test enum type")
     def test_enums(self):
-        import enum
         class Animal(enum.Enum):
             BEE = 1
             CAT = 2
             DOG = 3
         v = serpent.loads(serpent.dumps(Animal.CAT))
         self.assertEqual(2, v)
-        Animal2 = enum.Enum("Animals2", "BEE CAT DOG HORSE RABBIT")
+        class Animal2(enum.Enum):
+            BEE = 1
+            CAT = 2
+            DOG = 3
+            HORSE = 4
+            RABBIT = 5
         v = serpent.loads(serpent.dumps(Animal2.HORSE))
         self.assertEqual(4, v)
 
@@ -990,9 +998,7 @@ def testRegisterOrderPreserving(self):
         self.assertEqual(ItemsView, classes.pop(0))
         if sys.version_info >= (2, 7):
             self.assertEqual(collections.OrderedDict, classes.pop(0))
-        if sys.version_info >= (3, 4):
-            import enum
-            self.assertEqual(enum.Enum, classes.pop(0))
+        self.assertEqual(enum.Enum, classes.pop(0))
         self.assertEqual(BaseClass, classes.pop(0))
         self.assertEqual(SubClass, classes.pop(0))
         self.assertEqual(0, len(classes))

tox.ini

@@ -2,7 +2,9 @@
 envlist=py27,py34,py35,py36,py37,pypy,pypy3
 
 [testenv]
-deps=pytz
+deps=
+     pytz
+     enum34; python_version<"3.4"
 changedir={toxinidir}/tests
 commands=python -E -Wall -tt -bb test_serpent.py