test: add a JS unit test to verify filterSubVerticals

conftest.py

@@ -20,7 +20,8 @@
 # List of test classes that are backed by TransactionTestCase
 TTC = ['course_discovery/apps/course_metadata/management/commands/tests/test_refresh_course_metadata.py::'
        'RefreshCourseMetadataCommandTests',
-       'course_discovery/apps/course_metadata/tests/test_admin.py::ProgramAdminFunctionalTests']
+       'course_discovery/apps/course_metadata/tests/test_admin.py::ProgramAdminFunctionalTests',
+       'course_discovery/apps/tagging/tests/test_views.py::CourseTaggingDetailViewJSTests']
 
 
 class LoadScopeSchedulingDjangoOrdered(LoadScopeScheduling):

course_discovery/apps/tagging/tests/test_views.py

@@ -1,8 +1,12 @@
 from ddt import data, ddt
 from django.conf import settings
 from django.contrib.auth.models import Group
-from django.test import TestCase
+from django.test import LiveServerTestCase, TestCase
 from django.urls import reverse
+from selenium import webdriver
+from selenium.webdriver.common.by import By
+from selenium.webdriver.firefox.options import Options
+from selenium.webdriver.support.ui import Select, WebDriverWait
 
 from course_discovery.apps.core.tests.factories import UserFactory
 from course_discovery.apps.course_metadata.tests.factories import CourseFactory
@@ -68,6 +72,115 @@ def test_post_invalid_sub_vertical(self):
         self.assertContains(response, 'Sub-vertical does not belong to the selected vertical.')
 
 
+class CourseTaggingDetailViewJSTests(LiveServerTestCase):
+    """
+    Functional tests using Selenium to verify the JS script filterSubVerticals behavior in the CourseTaggingDetailView.
+    """
+
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        firefox_options = Options()
+        firefox_options.headless = True
+        cls.driver = webdriver.Firefox(options=firefox_options)
+        cls.driver.implicitly_wait(10)
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.driver.quit()
+        super().tearDownClass()
+
+    def setUp(self):
+        """
+        Create a superuser, a course, verticals and sub-verticals used for testing.
+        """
+        self.user = UserFactory(username='superuser_func', is_superuser=True, is_staff=True)
+        self.user.set_password('password')
+        self.user.save()
+
+        self.course = CourseFactory(title='Advanced Python')
+
+        self.vertical = VerticalFactory(name='AI')
+        self.sub_vertical = SubVerticalFactory(name='Machine Learning', vertical=self.vertical)
+
+        self.other_vertical = VerticalFactory(name='Business')
+        self.other_sub_vertical = SubVerticalFactory(name='Innovation', vertical=self.other_vertical)
+
+        self.multi_vertical = VerticalFactory(name='Data')
+        self.multi_sub_vertical1 = SubVerticalFactory(name='Analytics', vertical=self.multi_vertical)
+        self.multi_sub_vertical2 = SubVerticalFactory(name='Visualization', vertical=self.multi_vertical)
+
+        self.url = self.live_server_url + reverse('tagging:course_tagging_detail', kwargs={'uuid': self.course.uuid})
+        self.login_url = self.live_server_url + reverse('admin:login')
+
+        # Login via the admin login page as it does not share cookies with Django's test client.
+        self.driver.get(self.login_url)
+        self.driver.find_element(By.NAME, 'username').send_keys(self.user.username)
+        self.driver.find_element(By.NAME, 'password').send_keys('password')
+        self.driver.find_element(By.XPATH, "//input[@type='submit']").click()
+
+        self.driver.get(self.url)
+
+    def get_visible_options(self, select_id):
+        """
+        Returns a list of visible <option> elements for the given select element.
+        Visible options are defined as those with a 'data-vertical' attribute and no inline 'display: none' style.
+        """
+        select_element = self.driver.find_element(By.ID, select_id)
+        options = select_element.find_elements(By.TAG_NAME, 'option')
+        visible_options = [
+            option for option in options
+            if option.get_attribute('data-vertical') is not None and
+            'display: none' not in (option.get_attribute('style') or '')
+        ]
+        return visible_options
+
+    def filter_sub_verticals(self, vertical_slug, expected_slugs):
+        """
+        Selects the vertical with the given slug, triggers the JavaScript change event, and waits
+        until the expected sub-vertical options (by their slug values) are visible in the sub_vertical select.
+        Returns the list of visible option elements.
+        """
+        vertical_select = Select(self.driver.find_element(By.ID, 'vertical'))
+        vertical_select.select_by_value(vertical_slug)
+        self.driver.execute_script(
+            "document.getElementById('vertical').dispatchEvent(new Event('change'));"
+        )
+        # Wait until the visible sub-vertical options match the expected set.
+        WebDriverWait(self.driver, 5).until(
+            lambda d: set(
+                option.get_attribute('value')
+                for option in self.get_visible_options('sub_vertical')
+            ) == set(expected_slugs)
+        )
+        return self.get_visible_options('sub_vertical')
+
+    def test_filter_sub_verticals_javascript(self):
+        """
+        Verify that selecting a vertical with one sub-vertical (AI and Business) shows the expected single sub-vertical
+        and a vertical with two sub-verticals ('Data') shows both sub-verticals.
+        """
+        # Test for vertical 'AI' with one sub-vertical 'Machine Learning'
+        visible_options = self.filter_sub_verticals(self.vertical.slug, [self.sub_vertical.slug])
+        self.assertEqual(len(visible_options), 1)
+        self.assertEqual(visible_options[0].get_attribute('value'), self.sub_vertical.slug)
+
+        # Test for vertical 'Business' with one sub-vertical 'Innovation'
+        visible_options = self.filter_sub_verticals(self.other_vertical.slug, [self.other_sub_vertical.slug])
+        self.assertEqual(len(visible_options), 1)
+        self.assertEqual(visible_options[0].get_attribute('value'), self.other_sub_vertical.slug)
+
+        # Test for vertical 'Data' with two sub-verticals: 'Analytics' and 'Visualization'
+        visible_options = self.filter_sub_verticals(
+            self.multi_vertical.slug,
+            [self.multi_sub_vertical1.slug, self.multi_sub_vertical2.slug]
+        )
+        option_values = sorted([option.get_attribute('value') for option in visible_options])
+        expected_values = sorted([self.multi_sub_vertical1.slug, self.multi_sub_vertical2.slug])
+        self.assertEqual(len(visible_options), 2)
+        self.assertEqual(option_values, expected_values)
+
+
 @ddt
 class CourseListViewTests(BaseViewsTestCase):
     """Tests for the CourseListView."""