fix: support files with a unicode signature in the Instructor Dashboard API

Without this, files with BOM (byte order mark; generated e.g., by Microsoft
Excel) cannot be read properly.

(cherry picked from commit 7d8a502)

Author: Agrendalath

lms/djangoapps/instructor/tests/test_api.py

@@ -590,6 +590,7 @@ def test_instructor_level(self):
 
 
 @patch.dict(settings.FEATURES, {'ALLOW_AUTOMATED_SIGNUPS': True})
+@ddt.ddt
 class TestInstructorAPIBulkAccountCreationAndEnrollment(SharedModuleStoreTestCase, LoginEnrollmentTestCase):
     """
     Test Bulk account creation and enrollment from csv file
@@ -641,32 +642,15 @@ def setUp(self):
         )
 
     @patch('lms.djangoapps.instructor.views.api.log.info')
-    def test_account_creation_and_enrollment_with_csv(self, info_log):
-        """
-        Happy path test to create a single new user
-        """
-        csv_content = b"test_student@example.com,test_student_1,tester1,USA"
-        uploaded_file = SimpleUploadedFile("temp.csv", csv_content)
-        response = self.client.post(self.url, {'students_list': uploaded_file, 'email-students': True})
-        assert response.status_code == 200
-        data = json.loads(response.content.decode('utf-8'))
-        assert len(data['row_errors']) == 0
-        assert len(data['warnings']) == 0
-        assert len(data['general_errors']) == 0
-
-        manual_enrollments = ManualEnrollmentAudit.objects.all()
-        assert manual_enrollments.count() == 1
-        assert manual_enrollments[0].state_transition == UNENROLLED_TO_ENROLLED
-
-        # test the log for email that's send to new created user.
-        info_log.assert_called_with('email sent to new created user at %s', 'test_student@example.com')
-
-    @patch('lms.djangoapps.instructor.views.api.log.info')
-    def test_account_creation_and_enrollment_with_csv_with_blank_lines(self, info_log):
+    @ddt.data(
+        b"test_student@example.com,test_student_1,tester1,USA",  # Typical use case.
+        b"\ntest_student@example.com,test_student_1,tester1,USA\n\n",  # Blank lines.
+        b"\xef\xbb\xbftest_student@example.com,test_student_1,tester1,USA",  # Unicode signature (BOM).
+    )
+    def test_account_creation_and_enrollment_with_csv(self, csv_content, info_log):
         """
         Happy path test to create a single new user
         """
-        csv_content = b"\ntest_student@example.com,test_student_1,tester1,USA\n\n"
         uploaded_file = SimpleUploadedFile("temp.csv", csv_content)
         response = self.client.post(self.url, {'students_list': uploaded_file, 'email-students': True})
         assert response.status_code == 200
@@ -4385,7 +4369,7 @@ def call_add_users_to_cohorts(self, csv_data, suffix='.csv'):
         """
         # this temporary file will be removed in `self.tearDown()`
         __, file_name = tempfile.mkstemp(suffix=suffix, dir=self.tempdir)
-        with open(file_name, 'w') as file_pointer:
+        with open(file_name, 'w', encoding='utf-8-sig') as file_pointer:
             file_pointer.write(csv_data)
         with open(file_name) as file_pointer:
             url = reverse('add_users_to_cohorts', kwargs={'course_id': str(self.course.id)})

lms/djangoapps/instructor/views/api.py

@@ -339,7 +339,7 @@ def register_and_enroll_students(request, course_id):  # pylint: disable=too-man
         try:
             upload_file = request.FILES.get('students_list')
             if upload_file.name.endswith('.csv'):
-                students = list(csv.reader(upload_file.read().decode('utf-8').splitlines()))
+                students = list(csv.reader(upload_file.read().decode('utf-8-sig').splitlines()))
                 course = get_course_by_id(course_id)
             else:
                 general_errors.append({
@@ -1519,7 +1519,7 @@ def _cohorts_csv_validator(file_storage, file_to_validate):
     Verifies that the expected columns are present in the CSV used to add users to cohorts.
     """
     with file_storage.open(file_to_validate) as f:
-        reader = csv.reader(f.read().decode('utf-8').splitlines())
+        reader = csv.reader(f.read().decode('utf-8-sig').splitlines())
 
         try:
             fieldnames = next(reader)
@@ -3332,7 +3332,7 @@ def build_row_errors(key, _user, row_count):
         try:
             upload_file = request.FILES.get('students_list')
             if upload_file.name.endswith('.csv'):
-                students = list(csv.reader(upload_file.read().decode('utf-8').splitlines()))
+                students = list(csv.reader(upload_file.read().decode('utf-8-sig').splitlines()))
             else:
                 general_errors.append(_('Make sure that the file you upload is in CSV format with no '
                                         'extraneous characters or rows.'))