added useful comments

bookshare/functional_tests.py

@@ -263,6 +263,10 @@ class ListingTests(SeleniumSetUpTearDown):
 class LookoutTests(SeleniumSetUpTearDown):
     """Tests all the user interactions pertaining to the models in the lookouts app."""
 
+    def setUp(self):
+        # make sure that a Julius Caesar Lookout doesn't already exist
+        return super(LookoutTests, self).setUp()
+
     def tearDown(self):
         # delete the George Mason Lookout
         return super(LookoutTests, self).tearDown()

bookshare/lookouts/models.py

@@ -32,4 +32,5 @@ class Lookout(TimeStampedModel):
 
     class Meta:
         ordering = ['isbn']
+        # a student can't create the same lookout twice
         unique_together = ['owner', 'isbn']