[Telemetry] Ensure that story display names are unique

telemetry/telemetry/story/story_set.py

Index: telemetry/telemetry/story/story_set.py
diff --git a/telemetry/telemetry/story/story_set.py b/telemetry/telemetry/story/story_set.py
index 667cbd01ebb7b9b3114da16ae16933335b97f9ef..6fa319a9294a5057bbafd8f6604d57f173bf861b 100644
--- a/telemetry/telemetry/story/story_set.py
+++ b/telemetry/telemetry/story/story_set.py
@@ -32,6 +32,7 @@ class StorySet(object):
           storage.
     """
     self.stories = []
+    self.story_names_and_grouping_keys = set()

[nednguyen, 2016/12/02 19:59:58]

Can you make this private? Things that are not supposed to be touched/modified
by external should be private.

[eakuefner, 2016/12/02 20:28:58]

Done. Also made stories private, since now it's critical that stories and
story_names_and_grouping_keys should remain in sync.

     self._archive_data_file = archive_data_file
     self._wpr_archive_info = None
     archive_info.AssertValidCloudStorageBucket(cloud_storage_bucket)
@@ -98,7 +99,16 @@ class StorySet(object):
 
   def AddStory(self, story):
     assert isinstance(story, story_module.Story)
+    assert self._IsUnique(story), ('Tried to add story with duplicate display '
+                                   'name %s. Story display names should be '
+                                   'unique.' % story.display_name)
     self.stories.append(story)
+    self.story_names_and_grouping_keys.add(
+        story.display_name_and_grouping_key_tuple)
+
+  def _IsUnique(self, story):
+    return (story.display_name_and_grouping_key_tuple not in
+            self.story_names_and_grouping_keys)
 
   def RemoveStory(self, story):
     """Removes a Story.