Adding failing tests that show null=True model fields are won't validate if their value is omitted.

rest_framework/tests/models.py

@@ -116,3 +116,8 @@ class BlogPost(RESTFrameworkModel):
 class BlogPostComment(RESTFrameworkModel):
     text = models.TextField()
     blog_post = models.ForeignKey(BlogPost)
+
+
+class Person(RESTFrameworkModel):
+    name = models.CharField(max_length=10)
+    age = models.IntegerField(null=True, blank=True)

rest_framework/tests/serializer.py

@@ -43,6 +43,11 @@ class ActionItemSerializer(serializers.ModelSerializer):
         model = ActionItem
 
 
+class PersonSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Person
+
+
 class BasicTests(TestCase):
     def setUp(self):
         self.comment = Comment(
@@ -188,6 +193,14 @@ class ValidationTests(TestCase):
         self.assertFalse(serializer.is_valid())
         self.assertEquals(serializer.errors, {'non_field_errors': [u'Email address not in content']})
 
+    def test_null_is_true_fields(self):
+        """
+        Omitting a value for null-field should validate.
+        """
+        serializer = PersonSerializer({'name': 'marko'})
+        self.assertEquals(serializer.is_valid(), True)
+        self.assertEquals(serializer.errors, {})
+
 
 class MetadataTests(TestCase):
     def test_empty(self):