Refs #13614 -- Added test for admin's many-to-many widget data loss bug.

        self.assertEqual(list(self.school.alumni.all()),

                         [self.jason, self.peter])

    def test_back_button_bug(self):

        """

        Some browsers had a bug where navigating away from the change page

        and then clicking the browser's back button would clear the

        filter_horizontal/filter_vertical widgets (#13614).

        """

        self.school.students.set([self.lisa, self.peter])

        self.school.alumni.set([self.lisa, self.peter])

        self.admin_login(username='super', password='secret', login_url='/')

        change_url = reverse('admin:admin_widgets_school_change', args=(self.school.id,))

        self.selenium.get(self.live_server_url + change_url)

        # Navigate away and go back to the change form page.

        self.selenium.find_element_by_link_text('Home').click()

        self.selenium.back()

        self.wait_for('#id_students_from')

        expected_unselected_values = [

            str(self.arthur.id), str(self.bob.id), str(self.cliff.id),

            str(self.jason.id), str(self.jenny.id), str(self.john.id),

        ]

        expected_selected_values = [str(self.lisa.id), str(self.peter.id)]

        # Check that everything is still in place

        self.assertSelectOptions('#id_students_from', expected_unselected_values)

        self.assertSelectOptions('#id_students_to', expected_selected_values)

        self.assertSelectOptions('#id_alumni_from', expected_unselected_values)

        self.assertSelectOptions('#id_alumni_to', expected_selected_values)

class HorizontalVerticalFilterSeleniumChromeTests(HorizontalVerticalFilterSeleniumFirefoxTests):

    webdriver_class = 'selenium.webdriver.chrome.webdriver.WebDriver'