Adjust assessment check

To address sentry issue ECONPLAYGROUND-84

Author: nikolas

econplayground/main/tests/test_views.py

@@ -59,8 +59,12 @@ def test_get_no_assessment(self):
         g.assessment.delete()
         g.assessment = None
         g.save()
-        with self.assertRaises(ObjectDoesNotExist):
-            self.client.get(reverse('graph_detail', kwargs={'pk': g.pk}))
+
+        r = self.client.get(reverse('graph_detail', kwargs={'pk': g.pk}))
+
+        self.assertEqual(r.status_code, 200)
+        self.assertContains(r, g.title)
+        self.assertContains(r, g.topic.cohort.title)
 
 
 class GraphPickViewTest(LoggedInTestInstructorMixin, TestCase):

econplayground/main/views.py

@@ -300,7 +300,8 @@ def get_context_data(self, *args, **kwargs):
         ctx = super(GraphDetailView, self).get_context_data(*args, **kwargs)
 
         assessment_change_url = None
-        if self.object.assessment and user_is_instructor(self.request.user):
+        if hasattr(self.object, 'assessment') and self.object.assessment and \
+           user_is_instructor(self.request.user):
             assessment_change_url = reverse(
                 'admin:main_assessment_change',
                 kwargs={'object_id': self.object.assessment.pk})