[soc2009/model-validation] Added simple tests for ForeignKey validation.

git-svn-id: http://code.djangoproject.com/svn/django/branches/soc2009/model-validation@10879 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/modeltests/validation/models.py

@@ -8,6 +8,7 @@ class ModelToValidate(models.Model):
     name = models.CharField(max_length=100)
     created = models.DateTimeField(default=datetime.now)
     number = models.IntegerField()
+    parent = models.ForeignKey('self', blank=True, null=True)
 
     def validate(self):
         super(ModelToValidate, self).validate()