diff --git a/plone/app/discussion/tests/test_comment.py b/plone/app/discussion/tests/test_comment.py
index 999435b..d8b1dd2 100644
--- a/plone/app/discussion/tests/test_comment.py
+++ b/plone/app/discussion/tests/test_comment.py
@@ -5,106 +5,143 @@ from zope.component import createObject
 from Products.PloneTestCase.ptc import PloneTestCase
 from plone.app.discussion.tests.layer import DiscussionLayer
 
-from plone.app.discussion.interfaces import IComment, IConversation
+from plone.app.discussion.interfaces import IComment, IConversation, IReplies
 
 class CommentTest(PloneTestCase):
-    
+
     layer = DiscussionLayer
-    
+
     def afterSetUp(self):
         # First we need to create some content.
         self.loginAsPortalOwner()
         typetool = self.portal.portal_types
         typetool.constructContent('Document', self.portal, 'doc1')
-    
+
     def test_factory(self):
         comment1 = createObject('plone.Comment')
         self.assert_(IComment.providedBy(comment1))
-        
+
     def test_id(self):
         comment1 = createObject('plone.Comment')
         comment1.comment_id = 123
         self.assertEquals('123', comment1.id)
         self.assertEquals('123', comment1.getId())
         self.assertEquals(u'123', comment1.__name__)
-        
+
     def test_title(self):
         comment1 = createObject('plone.Comment')
         comment1.title = "New title"
         self.assertEquals("New title", comment1.Title())
-    
+
     def test_creator(self):
         comment1 = createObject('plone.Comment')
         comment1.creator = "Jim"
         self.assertEquals("Jim", comment1.Creator())
-        
+
     def test_traversal(self):
         # make sure comments are traversable, have an id, absolute_url and physical path
-        
+
         conversation = IConversation(self.portal.doc1).__of__(self.portal.doc1)
-        
+
         comment1 = createObject('plone.Comment')
         comment1.title = 'Comment 1'
         comment1.text = 'Comment text'
 
         new_comment1_id = conversation.addComment(comment1)
-        
+
         comment = self.portal.doc1.restrictedTraverse('++conversation++default/%s' % new_comment1_id)
         self.assert_(IComment.providedBy(comment))
         self.assertEquals('Comment 1', comment.title)
-        
+
         self.assertEquals(('', 'plone', 'doc1', '++conversation++default', str(new_comment1_id)), comment.getPhysicalPath())
         self.assertEquals('plone/doc1/%2B%2Bconversation%2B%2Bdefault/' + str(new_comment1_id), comment.absolute_url())
-        
+
     def test_workflow(self):
         self.portal.portal_workflow.setChainForPortalTypes(('Discussion Item',), ('simple_publication_workflow,'))
-        
+
         conversation = IConversation(self.portal.doc1).__of__(self.portal.doc1)
         comment1 = createObject('plone.Comment')
         new_comment1_id = conversation.addComment(comment1)
-        
+
         comment = conversation[new_comment1_id]
-        
+
         chain = self.portal.portal_workflow.getChainFor(comment)
         self.assertEquals(('simple_publication_workflow',), chain)
-        
+
         # ensure the initial state was entered and recorded
         self.assertEquals(1, len(comment.workflow_history['simple_publication_workflow']))
         self.assertEquals(None, comment.workflow_history['simple_publication_workflow'][0]['action'])
-        
+
         self.assertEquals('private', self.portal.portal_workflow.getInfoFor(comment, 'review_state'))
-    
+
     def test_fti(self):
         # test that we can look up an FTI for Discussion Item
-        
+
         self.assert_("Discussion Item" in self.portal.portal_types.objectIds())
-        
+
         comment1 = createObject('plone.Comment')
-        
+
         fti = self.portal.portal_types.getTypeInfo(comment1)
         self.assertEquals('Discussion Item', fti.getTypeInfo(comment1).getId())
 
 class RepliesTest(PloneTestCase):
-    
+
     # test the IReplies adapter on a comment
-    
+
     layer = DiscussionLayer
-    
+
     def afterSetUp(self):
         # First we need to create some content.
         self.loginAsPortalOwner()
         typetool = self.portal.portal_types
         typetool.constructContent('Document', self.portal, 'doc1')
-    
+
     def test_add_comment(self):
-        pass
-    
+        # Add comments to a CommentReplies adapter
+
+        # Create a conversation. In this case we doesn't assign it to an
+        # object, as we just want to check the Conversation object API.
+        conversation = IConversation(self.portal.doc1)
+
+        # Pretend that we have traversed to the comment by aq wrapping it.
+        conversation = conversation.__of__(self.portal.doc1)
+
+        # Add a comment to the conversation
+        replies = IReplies(conversation)
+
+        comment = createObject('plone.Comment')
+        comment.title = 'Comment 1'
+        comment.text = 'Comment text'
+
+        new_id = replies.addComment(comment)
+
+        # Add a reply to the CommentReplies adapter of the first comment
+        re_comment = createObject('plone.Comment')
+        re_comment.title = 'Re: Comment 1'
+        re_comment.text = 'Comment text'
+
+        replies = IReplies(comment)
+
+        new_re_id = replies.addComment(re_comment)
+
+        # check that replies provides the IReplies interface
+        self.assert_(IReplies.providedBy(replies))
+
+        # Make sure our comment was added
+        self.failUnless(new_re_id in replies)
+
+        # Make sure it is also reflected in the conversation
+        self.failUnless(new_re_id in conversation)
+
+        # Make sure the conversation has the correct comment id
+        self.assertEquals(conversation[new_re_id].comment_id, new_re_id)
+
     def test_delete_comment(self):
         pass
-    
+
     def test_dict_api(self):
         # ensure all operations use only top-level comments
         pass
-    
+
 def test_suite():
     return unittest.defaultTestLoader.loadTestsFromName(__name__)
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