Index: tests/regressiontests/forms/models.py
===================================================================
--- tests/regressiontests/forms/models.py       (revision 6363)
+++ tests/regressiontests/forms/models.py       (working copy)
@@ -2,7 +2,10 @@
 
 class BoundaryModel(models.Model): 
     positive_integer = models.PositiveIntegerField(null=True, blank=True)
-    
+
+class ForeignKeyModel(models.Model):
+    foreign_key = models.ForeignKey('self', null=True, blank=True)
+
 __test__ = {'API_TESTS': """
 >>> from django.newforms import form_for_model
 
@@ -18,4 +21,21 @@
 >>> f.is_valid() 
 False
 
+>>> from django.newforms import form_for_instance
+>>> fk1 = ForeignKeyModel()
+>>> fk1.save()
+>>> fk2 = ForeignKeyModel(foreign_key=fk1)
+>>> fk2.save()
+>>> fk2.foreign_key == fk1
+True
+>>> Form = form_for_instance(fk1, fields=[], formfield_callback=lambda f, initial: 'do nothing')
+>>> f = Form()
+>>> f.is_valid()
+False
+>>> f = Form({'foreign_key':fk1})
+>>> f.is_valid()
+True
+>>> f.errors
+{}
+
 """}