fixed flaky test from grading

common/test/acceptance/pages/studio/settings_graders.py

@@ -73,9 +73,14 @@ class GradingPage(SettingsPage):
         Drag and drop grade range.
         """
         self.wait_for_element_visibility(self.grade_ranges, "Grades ranges are visible")
+        # We have used jquery here to adjust the width of slider to
+        # desired range because drag and drop has behaved very inconsistently.
+        # This does not updates the text of range on the slider.
+        # So as a work around, we have used drag_and_drop without any offset
+        self.browser.execute_script('$(".ui-resizable").css("width","10")')
         action = ActionChains(self.browser)
         moveable_css = self.q(css='.ui-resizable-e').results[0]
-        action.drag_and_drop_by_offset(moveable_css, 100, 0).perform()
+        action.drag_and_drop_by_offset(moveable_css, 0, 0).perform()
 
     @property
     def grade_letters(self):

common/test/acceptance/tests/studio/test_studio_grading.py

@@ -112,3 +112,21 @@ class GradingPageTest(StudioCourseTest):
         self.grading_page.remove_grades(1)
         total_number_of_grades = self.grading_page.total_number_of_grades
         self.assertEqual(total_number_of_grades, 2)
+
+    def test_staff_can_move_grading_ranges(self):
+        """
+        Scenario: Users can move grading ranges
+            Given I have opened a new course in Studio
+            And I am viewing the grading settings
+            When I move a grading section
+            Then I see that the grade range has changed
+        """
+        grade_ranges = self.grading_page.grades_range
+        self.assertIn('0-50', grade_ranges)
+        self.grading_page.drag_and_drop_grade()
+        grade_ranges = self.grading_page.grades_range
+        self.assertIn(
+            '0-3',
+            grade_ranges,
+            'expected range: 0-3, not found in grade ranges:{}'.format(grade_ranges)
+        )