Fix regression with Model instantiation

We need to pass the class, not an instance, to check_registration, but I
neglected to address that when moving the check_registration call inside
of Model.__init__. This bug was masked by a bug in check_registration
itself (variable clobbering in a loop).

Author: chadwhitacre

postgres/__init__.py

@@ -673,8 +673,9 @@ def check_registration(self, ModelSubclass):
 
         """
         key = None
-        for key, v in self.model_registry.items():
+        for k, v in self.model_registry.items():
             if v is ModelSubclass:
+                key = k
                 break
         if key is None:
             raise NotRegistered(ModelSubclass)

postgres/orm.py

@@ -223,7 +223,7 @@ class Model(object):
     def __init__(self, record):
         if self.db is None:
             raise NotBound(self)
-        self.db.check_registration(self)
+        self.db.check_registration(self.__class__)
         self.__read_only_attributes = record.keys()
         self.set_attributes(**record)
 

tests.py

@@ -4,10 +4,11 @@
 from collections import namedtuple
 from unittest import TestCase
 
-from postgres import Postgres
+from postgres import Postgres, NotRegistered
 from postgres.cursors import TooFew, TooMany, SimpleDictCursor
 from postgres.orm import ReadOnly
 from psycopg2 import InterfaceError, ProgrammingError
+from pytest import raises
 
 
 DATABASE_URL = os.environ['DATABASE_URL']
@@ -266,6 +267,10 @@ def assign():
             one.bar = "blah"
         self.assertRaises(ReadOnly, assign)
 
+    def test_check_register_raises_if_passed_a_model_instance(self):
+        obj = self.MyModel({'bar': 'baz'})
+        raises(NotRegistered, self.db.check_registration, obj)
+
 
 # cursor_factory
 # ==============