Upgrading Entity.property to properties map in datastore.

Towards #1288.

gcloud/datastore/helpers.py

@@ -124,9 +124,7 @@ def _new_value_pb(entity_pb, name):
     :rtype: :class:`gcloud.datastore._generated.entity_pb2.Value`
     :returns: The new ``Value`` protobuf that was added to the entity.
     """
-    property_pb = entity_pb.property.add()
-    property_pb.name = name
-    return property_pb.value
+    return entity_pb.properties.get_or_create(name)
 
 
 def _property_tuples(entity_pb):
@@ -139,8 +137,7 @@ def _property_tuples(entity_pb):
     :returns: An iterator that yields tuples of a name and ``Value``
               corresponding to properties on the entity.
     """
-    for property_pb in entity_pb.property:
-        yield property_pb.name, property_pb.value
+    return six.iteritems(entity_pb.properties)
 
 
 def entity_from_protobuf(pb):

gcloud/datastore/test_helpers.py

@@ -29,9 +29,8 @@ def test_it(self):
         result = self._callFUT(entity_pb, name)
 
         self.assertTrue(isinstance(result, entity_pb2.Value))
-        self.assertEqual(len(entity_pb.property), 1)
-        self.assertEqual(entity_pb.property[0].name, name)
-        self.assertEqual(entity_pb.property[0].value, result)
+        self.assertEqual(len(entity_pb.properties), 1)
+        self.assertEqual(entity_pb.properties[name], result)
 
 
 class Test__property_tuples(unittest2.TestCase):
@@ -53,7 +52,8 @@ def test_it(self):
 
         result = self._callFUT(entity_pb)
         self.assertTrue(isinstance(result, types.GeneratorType))
-        self.assertEqual(list(result), [(name1, val_pb1), (name2, val_pb2)])
+        self.assertEqual(sorted(result),
+                         sorted([(name1, val_pb1), (name2, val_pb2)]))
 
 
 class Test_entity_from_protobuf(unittest2.TestCase):