NotUniqueError gracefully replacing ambiguous OperationError when appropriate

tests/test_document.py

@@ -1013,6 +1013,9 @@ class DocumentTest(unittest.TestCase):
 
         # Two posts with the same slug is not allowed
         post2 = BlogPost(title='test2', slug='test')
+        self.assertRaises(NotUniqueError, post2.save)
+
+        # Ensure backwards compatibilty for errors
         self.assertRaises(OperationError, post2.save)
 
     def test_unique_with(self):
@@ -1063,7 +1066,7 @@ class DocumentTest(unittest.TestCase):
 
         # Now there will be two docs with the same sub.slug
         post3 = BlogPost(title='test3', sub=SubDocument(year=2010, slug='test'))
-        self.assertRaises(OperationError, post3.save)
+        self.assertRaises(NotUniqueError, post3.save)
 
         BlogPost.drop_collection()
 
@@ -1090,11 +1093,11 @@ class DocumentTest(unittest.TestCase):
 
         # Now there will be two docs with the same sub.slug
         post3 = BlogPost(title='test3', sub=SubDocument(year=2010, slug='test'))
-        self.assertRaises(OperationError, post3.save)
+        self.assertRaises(NotUniqueError, post3.save)
 
         # Now there will be two docs with the same title and year
         post3 = BlogPost(title='test1', sub=SubDocument(year=2009, slug='test-1'))
-        self.assertRaises(OperationError, post3.save)
+        self.assertRaises(NotUniqueError, post3.save)
 
         BlogPost.drop_collection()
 
@@ -1117,7 +1120,7 @@ class DocumentTest(unittest.TestCase):
         try:
             cust_dupe.save()
             raise AssertionError, "We saved a dupe!"
-        except OperationError:
+        except NotUniqueError:
             pass
         Customer.drop_collection()