diff --git a/openassessment/runtime_imports/classes.py b/openassessment/runtime_imports/classes.py
index 89cdd4b4d3..e518f9d27e 100644
--- a/openassessment/runtime_imports/classes.py
+++ b/openassessment/runtime_imports/classes.py
@@ -41,6 +41,7 @@ def import_waffle_flag():
 def import_student_module():
     """
     Helper method that imports StudentModule from edx-platform at runtime.
+    https://github.com/openedx/edx-platform/blob/master/lms/djangoapps/courseware/models.py#L79
     """
     from lms.djangoapps.courseware.models import StudentModule
     return StudentModule
diff --git a/openassessment/xblock/test/test_allow_resubmission.py b/openassessment/xblock/test/test_allow_resubmission.py
index 4c0f2c5196..a827d2a132 100644
--- a/openassessment/xblock/test/test_allow_resubmission.py
+++ b/openassessment/xblock/test/test_allow_resubmission.py
@@ -13,10 +13,12 @@ class ConfigDataMock:
 
     def __init__(self):
         self.allow_learner_resubmissions = True
-        self.submission_due = "2029-01-01T00:00:00+00:00"
         self.resubmissions_grace_period_hours = 0
         self.resubmissions_grace_period_minutes = 0
 
+    def is_closed(self, step: str): # pylint: disable=unused-argument
+        return (False, None, None, None)
+
 
 class WorkflowDataMock:
     """Mock class for the WorkflowAPI object."""
@@ -104,6 +106,7 @@ def test_allow_resubmission_resubmissions_not_allowed(self):
         Test case for the allow_resubmission function when learner resubmissions are not allowed.
         """
         self.config_data.allow_learner_resubmissions = False
+
         result = allow_resubmission(
             self.config_data, self.workflow_data, self.submission_data
         )
@@ -114,7 +117,7 @@ def test_allow_resubmission_submission_date_exceeded(self):
         """
         Test case for the allow_resubmission function when the submission date has been exceeded.
         """
-        self.config_data.submission_due = "2020-01-01T00:00:00+00:00"
+        self.config_data.is_closed = lambda step: (True, "due", None, None)
 
         result = allow_resubmission(
             self.config_data, self.workflow_data, self.submission_data
diff --git a/openassessment/xblock/test/test_submission.py b/openassessment/xblock/test/test_submission.py
index 376cda2bff..de961d7333 100644
--- a/openassessment/xblock/test/test_submission.py
+++ b/openassessment/xblock/test/test_submission.py
@@ -153,23 +153,54 @@ def test_cannot_submit_in_preview_mode(self, xblock):
         self.assertEqual(resp[1], "ENOPREVIEW")
         self.assertIsNot(resp[2], None)
 
+    @patch("openassessment.xblock.openassessmentblock.import_student_module")
     @patch("openassessment.xblock.openassessmentblock.reset_student_attempts")
     @patch("openassessment.xblock.openassessmentblock.get_user_by_username_or_email")
     @scenario("data/basic_scenario.xml", user_id="Bob")
-    def test_reset_submission(self, xblock, mock_user: Mock, mock_reset: Mock):
+    def test_reset_submission(
+        self, xblock, mock_user: Mock, mock_reset: Mock, mock_student_module: Mock
+    ):
         xblock.xmodule_runtime = Mock(course_id=COURSE_ID)
         mock_user.return_value = "test-user"
         mock_reset.return_value = True
+        mock_student_module.return_value = "test-student-module"
 
         resp = self.request(xblock, "reset_submission", json.dumps({}), response_format="json")
+
         self.assertTrue(resp["success"])
         self.assertEqual(resp["msg"], "Submission reset successfully.")
 
+    @patch("openassessment.xblock.openassessmentblock.import_student_module")
+    @patch("openassessment.xblock.openassessmentblock.get_user_by_username_or_email")
     @scenario("data/basic_scenario.xml", user_id="Bob")
-    def test_reset_submission_error(self, xblock):
+    def test_reset_submission_user_not_found_error(
+        self, xblock, mock_user: Mock, mock_student_module: Mock
+    ):
+        mock_student_module.return_value = "test-student-module"
+        mock_user.side_effect = get_user_model().DoesNotExist
+
         resp = self.request(xblock, "reset_submission", json.dumps({}), response_format="json")
         self.assertFalse(resp["success"])
-        self.assertEqual(resp["msg"], "Error resetting submission.")
+        self.assertEqual(resp["msg"], "The user does not exist.")
+
+    @patch("openassessment.xblock.openassessmentblock.import_student_module")
+    @patch("openassessment.xblock.openassessmentblock.reset_student_attempts")
+    @patch("openassessment.xblock.openassessmentblock.get_user_by_username_or_email")
+    @scenario("data/basic_scenario.xml", user_id="Bob")
+    def test_reset_submission_submission_not_found_error(
+        self, xblock, mock_user: Mock, mock_reset: Mock, mock_student_module: Mock
+    ):
+        xblock.xmodule_runtime = Mock(course_id=COURSE_ID)
+        mock_user.side_effect = "test-user"
+        error_mock = Mock()
+        error_mock.DoesNotExist = ObjectDoesNotExist
+        mock_student_module.return_value = error_mock
+        mock_reset.side_effect = ObjectDoesNotExist
+
+        resp = self.request(xblock, "reset_submission", json.dumps({}), response_format="json")
+
+        self.assertFalse(resp["success"])
+        self.assertEqual(resp["msg"], "There is no submission to reset.")
 
     @scenario('data/over_grade_scenario.xml', user_id='Alice')
     def test_closed_submissions(self, xblock):