Merge pull request #363 from edx/dan-f/fix-negative-video-bars

Fix negative video bars.
openedx-unsupported · Oct 7, 2015 · 1ff51fd · 1ff51fd
2 parents 473e691 + 363e452
commit 1ff51fd
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diff --git a/analytics_dashboard/courses/presenters/engagement.py b/analytics_dashboard/courses/presenters/engagement.py
@@ -131,7 +131,7 @@ def attach_computed_data(self, video):
             video['id'] = video.pop('encoded_module_id')
 
         total = max([video['users_at_start'], video['users_at_end']])
-        start_only_users = video['users_at_start'] - video['users_at_end']
+        start_only_users = max(video['users_at_start'] - video['users_at_end'], 0)
         video.update({
             'end_percent': utils.math.calculate_percent(video['users_at_end'], total),
             'start_only_users': start_only_users,

diff --git a/analytics_dashboard/courses/tests/test_presenters.py b/analytics_dashboard/courses/tests/test_presenters.py
@@ -285,6 +285,22 @@ def test_attach_computed_data(self):
             'start_only_percent': start_only_users / max_users,
         })
 
+    def test_greater_users_at_end(self):
+        module_data = {
+            'encoded_module_id': self.VIDEO_ID,
+            'users_at_start': 0,
+            'users_at_end': 1
+        }
+        self.presenter.attach_computed_data(module_data)
+        self.assertDictEqual(module_data, {
+            'id': self.VIDEO_ID,
+            'users_at_start': 0,
+            'users_at_end': 1,
+            'end_percent': 1.0,
+            'start_only_users': 0,
+            'start_only_percent': 0.0,
+        })
+
     def test_attach_aggregated_data_to_parent(self):
         parent = {
             'num_modules': 2,