Merge pull request #539 from edx/dcs/remove-attempt

Remove exam attempt on backend when it's deleted in the LMS

docs/backends.rst

@@ -148,6 +148,14 @@ For convenience, the PS should return the exam instructions and the software dow
         "download_url": "http://my-proctoring.com/download"
     }
 
+``DELETE``: removes attempt on PS server
+
+When an attempt is deleted on the Open edX server, it will make a ``DELETE`` request on the PS server. On success, return::
+
+    {
+        "status": "deleted"
+    }
+
 
 User management endpoint
 ^^^^^^^^^^^^^^^^^^^^^^^^

edx_proctoring/backends/backend.py

@@ -54,6 +54,13 @@ def mark_erroneous_exam_attempt(self, exam, attempt):
         """
         raise NotImplementedError()
 
+    @abc.abstractmethod
+    def remove_exam_attempt(self, exam, attempt):
+        """
+        Method that removes the exam attempt from the backend's system
+        """
+        raise NotImplementedError()
+
     @abc.abstractmethod
     def get_software_download_url(self):
         """

edx_proctoring/backends/mock.py

@@ -74,6 +74,9 @@ def mark_erroneous_exam_attempt(self, exam, attempt):
         """
         return None
 
+    def remove_exam_attempt(self, exam, attempt):
+        return True
+
     def get_software_download_url(self):
         """
         Returns

edx_proctoring/backends/null.py

@@ -41,6 +41,9 @@ def mark_erroneous_exam_attempt(self, exam, attempt):
         """
         return None
 
+    def remove_exam_attempt(self, exam, attempt):
+        return True
+
     def get_software_download_url(self):
         """
         Returns the URL that the user needs to go to in order to download

edx_proctoring/backends/rest.py

@@ -216,6 +216,16 @@ def stop_exam_attempt(self, exam, attempt):
             method='PATCH')
         return response.get('status')
 
+    def remove_exam_attempt(self, exam, attempt):
+        """
+        Removes the exam attempt on the backend provider's server
+        """
+        response = self._make_attempt_request(
+            exam,
+            attempt,
+            method='DELETE')
+        return response.get('status', None) == 'deleted'
+
     def mark_erroneous_exam_attempt(self, exam, attempt):
         """
         Method that is responsible for communicating with the backend provider

edx_proctoring/backends/software_secure.py

@@ -121,6 +121,9 @@ def mark_erroneous_exam_attempt(self, exam, attempt):
         """
         return None
 
+    def remove_exam_attempt(self, exam, attempt):
+        return None
+
     def get_software_download_url(self):
         """
         Returns the URL that the user needs to go to in order to download

edx_proctoring/backends/tests/test_backend.py

@@ -29,6 +29,7 @@ class TestBackendProvider(ProctoringBackendProvider):
 
     last_retire_user = None
     attempt_error = None
+    last_attempt_remove = None
 
     def register_exam_attempt(self, exam, context):
         """
@@ -60,6 +61,10 @@ def mark_erroneous_exam_attempt(self, exam, attempt):
         """
         return None
 
+    def remove_exam_attempt(self, exam, attempt):
+        self.last_attempt_remove = (exam, attempt)
+        return True
+
     def get_software_download_url(self):
         """
         Returns the URL that the user needs to go to in order to download
@@ -144,6 +149,12 @@ def mark_erroneous_exam_attempt(self, exam, attempt):
             attempt
         )
 
+    def remove_exam_attempt(self, exam, attempt):
+        return super(PassthroughBackendProvider, self).remove_exam_attempt(
+            exam,
+            attempt
+        )
+
     def get_software_download_url(self):
         """
         Returns the URL that the user needs to go to in order to download
@@ -191,6 +202,9 @@ def test_raises_exception(self):
         with self.assertRaises(NotImplementedError):
             provider.mark_erroneous_exam_attempt(None, None)
 
+        with self.assertRaises(NotImplementedError):
+            provider.remove_exam_attempt(None, None)
+
         with self.assertRaises(NotImplementedError):
             provider.on_exam_saved(None)
 

edx_proctoring/backends/tests/test_rest.py

@@ -242,6 +242,17 @@ def test_update_exam_attempt_status(self, provider_method_name, corresponding_st
         status = getattr(self.provider, provider_method_name)(self.backend_exam['external_id'], attempt_id)
         self.assertEqual(status, corresponding_status)
 
+    @responses.activate
+    def test_remove_attempt(self):
+        attempt_id = 2
+        responses.add(
+            responses.DELETE,
+            url=self.provider.exam_attempt_url.format(exam_id=self.backend_exam['external_id'], attempt_id=attempt_id),
+            json={'status': "deleted"}
+        )
+        status = self.provider.remove_exam_attempt(self.backend_exam['external_id'], attempt_id)
+        self.assertTrue(status)
+
     def test_on_review_callback(self):
         """
         on_review_callback should just return the payload

edx_proctoring/signals.py

@@ -1,4 +1,6 @@
 "edx-proctoring signals"
+import logging
+
 from django.db.models.signals import pre_save, post_save, pre_delete
 from django.dispatch import receiver
 
@@ -9,6 +11,8 @@
 from edx_proctoring.utils import emit_event, locate_attempt_by_attempt_code
 from edx_proctoring.backends import get_backend_provider
 
+log = logging.getLogger(__name__)
+
 
 @receiver(pre_save, sender=models.ProctoredExam)
 def check_for_category_switch(sender, instance, **kwargs):  # pylint: disable=unused-argument
@@ -106,6 +110,14 @@ def on_attempt_changed(sender, instance, signal, **kwargs):  # pylint: disable=u
                 return
         else:
             return
+    else:
+        # remove the attempt on the backend
+        # timed exams have no backend
+        backend = get_backend_provider(name=instance.proctored_exam.backend)
+        if backend:
+            result = backend.remove_exam_attempt(instance.proctored_exam.external_id, instance.external_id)
+            if not result:
+                log.error('Failed to remove attempt %d from %s', instance.id, backend.verbose_name)
     models.archive_model(models.ProctoredExamStudentAttemptHistory, instance, id='attempt_id')
 
 

edx_proctoring/tests/test_api.py

@@ -650,7 +650,14 @@ def test_remove_exam_attempt(self):
 
         proctored_exam_student_attempt = self._create_unstarted_exam_attempt()
         remove_exam_attempt(proctored_exam_student_attempt.id, requesting_user=self.user)
+        test_backend = get_backend_provider(name='test')
 
+        self.assertEqual(
+            test_backend.last_attempt_remove, (
+                proctored_exam_student_attempt.proctored_exam.external_id,
+                proctored_exam_student_attempt.external_id
+            )
+        )
         with self.assertRaises(StudentExamAttemptDoesNotExistsException):
             remove_exam_attempt(proctored_exam_student_attempt.id, requesting_user=self.user)