fix the bug where hitting software secure callback URL second time would revert…

fix the bug where hitting software secure callback URL second time  would revert the state back to 'ready to start' from 'started'

edx_proctoring/callbacks.py

@@ -48,7 +48,8 @@ def start_exam_callback(request, attempt_code):  # pylint: disable=unused-argume
             status=404
         )
 
-    mark_exam_attempt_as_ready(attempt['proctored_exam']['id'], attempt['user']['id'])
+    if attempt['status'] == "created":
+        mark_exam_attempt_as_ready(attempt['proctored_exam']['id'], attempt['user']['id'])
 
     template = loader.get_template('proctored_exam/proctoring_launch_callback.html')
 

edx_proctoring/tests/test_views.py

@@ -515,6 +515,47 @@ class TestStudentProctoredExamAttempt(LoggedInTestCase):
         attempt = get_exam_attempt_by_id(old_attempt_id)
         self.assertIsNotNone(attempt['started_at'])
 
+    def test_start_exam_callback(self):
+        """
+        Test that hitting software secure callback URL twice does not change the state
+        from 'started' back to 'ready to start'
+        """
+        # Create an exam.
+        proctored_exam = ProctoredExam.objects.create(
+            course_id='a/b/c',
+            content_id='test_content',
+            exam_name='Test Exam',
+            external_id='123aXqe3',
+            time_limit_mins=90,
+            is_proctored=True
+        )
+        attempt_id = create_exam_attempt(proctored_exam.id, self.user.id)
+        attempt = get_exam_attempt_by_id(attempt_id)
+        self.assertEqual(attempt['status'], "created")
+
+        # hit callback and verify that exam status is 'ready to start'
+        code = attempt['attempt_code']
+        self.client.get(
+            reverse('edx_proctoring.anonymous.proctoring_launch_callback.start_exam', kwargs={'attempt_code': code})
+        )
+        attempt = get_exam_attempt_by_id(attempt_id)
+        self.assertEqual(attempt['status'], "ready_to_start")
+
+        # update exam status to 'started'
+        exam_id = attempt['proctored_exam']['id']
+        user_id = attempt['user']['id']
+        update_attempt_status(exam_id, user_id, ProctoredExamStudentAttemptStatus.started)
+        attempt = get_exam_attempt_by_id(attempt_id)
+        self.assertEqual(attempt['status'], "started")
+
+        # hit callback again and verify that status is still 'started' and not 'ready to start'
+        self.client.get(
+            reverse('edx_proctoring.anonymous.proctoring_launch_callback.start_exam', kwargs={'attempt_code': code})
+        )
+        attempt = get_exam_attempt_by_id(attempt_id)
+        self.assertEqual(attempt['status'], "started")
+        self.assertFalse(attempt['status'] == "ready_to_start")
+
     def test_attempt_readback(self):
         """
         Confirms that an attempt can be read