test: add test for num queries

edx_exams/apps/core/management/commands/test/test_bulk_add_course_staff.py

@@ -55,16 +55,15 @@ def test_add_course_staff_with_new_user(self):
             call_command(self.command, f'--csv_path={csv.name}')
             assert CourseStaffRole.objects.filter(course_id='course-v1:edx+test+f20').count() == 1
 
-    def test_add_course_staff_with_batch_size(self):
+    def test_add_course_staff_with_not_default_batch_size(self):
         lines = ['pam,[email protected],staff,course-v1:edx+test+f20\n',
                  'sam,[email protected],staff,course-v1:edx+test+f20\n']
         with NamedTemporaryFile() as csv:
             csv = self._write_test_csv(csv, lines)
             call_command(self.command, f'--csv_path={csv.name}', '--batch_size=1')
             assert CourseStaffRole.objects.filter(course_id='course-v1:edx+test+f20').count() == 2
 
-    def test_add_course_staff_with_batch_delay(self):
-        # todo: test batch delay
+    def test_add_course_staff_with_not_default_batch_delay(self):
         lines = ['pam,[email protected],staff,course-v1:edx+test+f20\n',
                  'sam,[email protected],staff,course-v1:edx+test+f20\n']
         with NamedTemporaryFile() as csv:
@@ -73,11 +72,14 @@ def test_add_course_staff_with_batch_delay(self):
             assert CourseStaffRole.objects.filter(course_id='course-v1:edx+test+f20').count() == 2
 
     def test_num_queries_correct(self):
-        # todo: test num queries correct
-        lines = ['pam,[email protected],staff,course-v1:edx+test+f20\n',
-                 'sam,[email protected],staff,course-v1:edx+test+f20\n']
+        """
+        Expect the number of queries to be 3 + 3 * number of lines
+        - 2 for savepoint/release savepoint, 1 for count check below, 1 to get existing usernames
+        - 3 for each user, assuming not existing (1 to create user, 1 to get user, 1 to add course role)
+        """
+        num_lines = 20
+        lines = [f'pam{i},pam{i}@pond.com,staff,course-v1:edx+test+f20\n' for i in range(num_lines)]
         with NamedTemporaryFile() as csv:
             csv = self._write_test_csv(csv, lines)
-            with self.assertNumQueries(2):
-                call_command(self.command, f'--csv_path={csv.name}', '--batch_size=1', '--batch_delay=2')
-                assert CourseStaffRole.objects.filter(course_id='course-v1:edx+test+f20').count() == 2
+            with self.assertNumQueries(3 + 3 * num_lines):
+                call_command(self.command, f'--csv_path={csv.name}')