Improve test failure message

lms/djangoapps/certificates/models.py

@@ -302,6 +302,12 @@ class GeneratedCertificate(models.Model):
         else:
             return query.values('status').annotate(count=Count('status'))
 
+    def __repr__(self):
+        return "<GeneratedCertificate: {course_id}, user={user}>".format(
+            course_id=self.course_id,
+            user=self.user
+        )
+
     def invalidate(self):
         """
         Invalidate Generated Certificate by  marking it 'unavailable'.

lms/djangoapps/certificates/tests/test_api.py

@@ -369,6 +369,7 @@ class CertificateGetTests(SharedModuleStoreTestCase):
 
     @classmethod
     def tearDownClass(cls):
+        super(CertificateGetTests, cls).tearDownClass()
         cls.freezer.stop()
 
     def test_get_certificate_for_user(self):

lms/djangoapps/certificates/tests/test_webview_views.py

@@ -721,7 +721,7 @@ class CertificatesViewsTests(CommonCertificatesTestCase):
             course_id=unicode(self.course.id)
         )
         self.cert.delete()
-        self.assertEqual(len(GeneratedCertificate.eligible_certificates.all()), 0)
+        self.assertListEqual(list(GeneratedCertificate.eligible_certificates.all()), [])
 
         response = self.client.get(test_url)
         self.assertIn('invalid', response.content)
@@ -744,7 +744,7 @@ class CertificatesViewsTests(CommonCertificatesTestCase):
         preview mode. Either the certificate is marked active or not.
         """
         self.cert.delete()
-        self.assertEqual(len(GeneratedCertificate.eligible_certificates.all()), 0)
+        self.assertListEqual(list(GeneratedCertificate.eligible_certificates.all()), [])
         self._add_course_certificates(count=1, signatory_count=2)
         test_url = get_certificate_url(
             user_id=self.user.id,