Fix assert_max_length schematics

CHANGES.rst

@@ -4,6 +4,12 @@ Changelog
 Here you can see the full list of changes between each SQLAlchemy-Utils release.
 
 
+0.27.6 (2014-10-29)
+^^^^^^^^^^^^^^^^^^^
+
+- Fixed assert_max_length not working with non nullable columns
+
+
 0.27.5 (2014-10-24)
 ^^^^^^^^^^^^^^^^^^^
 

sqlalchemy_utils/asserts.py

@@ -68,7 +68,7 @@ def _expect_successful_update(obj, field, value, reraise_exc):
 
 def _expect_failing_update(obj, field, value, expected_exc):
     with raises(expected_exc):
-        _update_field(obj, field, None)
+        _update_field(obj, field, value)
     session = sa.orm.object_session(obj)
     session.rollback()
 

tests/test_asserts.py

@@ -31,13 +31,13 @@ class AssertionTestCase(TestCase):
             id = sa.Column(sa.Integer, primary_key=True)
             name = sa.Column(sa.String(20))
             age = sa.Column(sa.Integer, nullable=False)
-            email = sa.Column(sa.String(200), unique=True)
+            email = sa.Column(sa.String(200), nullable=False, unique=True)
 
         self.User = User
 
     def setup_method(self, method):
         TestCase.setup_method(self, method)
-        user = self.User(name='Someone', age=15)
+        user = self.User(name='Someone', email='someone@example.com', age=15)
         self.session.add(user)
         self.session.commit()
         self.user = user
@@ -73,6 +73,10 @@ class TestAssertMaxLength(AssertionTestCase):
         assert_max_length(self.user, 'name', 20)
         assert_max_length(self.user, 'name', 20)
 
+    def test_with_non_nullable_column(self):
+        assert_max_length(self.user, 'email', 200)
+        assert_max_length(self.user, 'email', 200)
+
     def test_smaller_than_max_length(self):
         with raises(AssertionError):
             assert_max_length(self.user, 'name', 19)