PYTHON-318 - Fix for SON pickling protocol 2

Updated tests to check protocol pickling as well

bson/son.py

@@ -72,6 +72,11 @@ class SON(dict):
         self.update(data)
         self.update(kwargs)
 
+    def __new__(cls, *args, **kwargs):
+        instance = super(SON, cls).__new__(cls, *args, **kwargs)
+        instance.__keys = []
+        return instance
+
     def __repr__(self):
         result = []
         for key in self.__keys:
@@ -214,3 +219,4 @@ class SON(dict):
         for k, v in self.iteritems():
             out[k] = copy.deepcopy(v, memo)
         return out
+

test/test_dbref.py

@@ -125,9 +125,10 @@ class TestDBRef(unittest.TestCase):
 
     def test_pickling(self):
         dbr = DBRef('coll', 5, foo='bar')
-        pkl = pickle.dumps(dbr)
-        dbr2 = pickle.loads(pkl)
-        self.assertEqual(dbr, dbr2)
+        for protocol in [0, 1, 2, -1]:
+            pkl = pickle.dumps(dbr, protocol=protocol)
+            dbr2 = pickle.loads(pkl)
+            self.assertEqual(dbr, dbr2)
 
     def test_dbref_hash(self):
         dbref_1a = DBRef('collection', 'id', 'database')

test/test_objectid.py

@@ -133,7 +133,9 @@ class TestObjectId(unittest.TestCase):
 
     def test_pickling(self):
         orig = ObjectId()
-        self.assertEqual(orig, pickle.loads(pickle.dumps(orig)))
+        for protocol in [0, 1, 2, -1]:
+            pkl = pickle.dumps(orig, protocol=protocol)
+            self.assertEqual(orig, pickle.loads(pkl))
 
     def test_pickle_backwards_compatability(self):
 

test/test_son.py

@@ -16,6 +16,7 @@
 
 import unittest
 import sys
+import pickle
 sys.path[0:0] = [""]
 
 from bson.son import SON
@@ -53,6 +54,27 @@ class TestSON(unittest.TestCase):
         self.assertEqual(dict, c.to_dict()["blah"][0].__class__)
         self.assertEqual(dict, d.to_dict()["blah"]["foo"].__class__)
 
+    def test_pickle(self):
+
+        simple_son = SON([])
+        complex_son = SON([('son', simple_son), ('list', [simple_son, simple_son])])
+
+        for protocol in [0, 1, 2, -1]:
+            pickled = pickle.loads(pickle.dumps(complex_son, protocol=protocol))
+            self.assertEquals(pickled['son'], pickled['list'][0])
+            self.assertEquals(pickled['son'], pickled['list'][1])
+
+    def test_pickle_backwards_compatability(self):
+
+        # This string was generated by pickling a SON object in pymongo
+        # version 2.1.1
+        pickled_with_2_1_1 = (
+            "ccopy_reg\n_reconstructor\np0\n(cbson.son\nSON\np1\n"
+            "c__builtin__\ndict\np2\n(dp3\ntp4\nRp5\n(dp6\n"
+            "S'_SON__keys'\np7\n(lp8\nsb."
+        )
+        son_2_1_1 = pickle.loads(pickled_with_2_1_1)
+        self.assertEqual(son_2_1_1, SON([]))
 
 if __name__ == "__main__":
     unittest.main()

test/test_timestamp.py

@@ -49,8 +49,10 @@ class TestTimestamp(unittest.TestCase):
         dc = copy.deepcopy(d)
         self.assertEqual(dc, t.as_datetime())
 
-        dp = pickle.loads(pickle.dumps(d))
-        self.assertEqual(dp, t.as_datetime())
+        for protocol in [0, 1, 2, -1]:
+            pkl = pickle.dumps(d, protocol=protocol)
+            dp = pickle.loads(pkl)
+            self.assertEqual(dp, t.as_datetime())
 
     def test_exceptions(self):
         self.assertRaises(TypeError, Timestamp)