Refactored LMS so all potential stale element exceptions are avoided

common/djangoapps/terrain/ui_helpers.py

@@ -10,6 +10,7 @@ from selenium.webdriver.support import expected_conditions as EC
 from selenium.webdriver.common.by import By
 from selenium.webdriver.support.ui import WebDriverWait
 from lettuce.django import django_url
+from nose.tools import assert_true
 
 
 @world.absorb
@@ -142,14 +143,44 @@ def id_click(elem_id):
 
 
 @world.absorb
-def css_fill(css_selector, text):
-    assert is_css_present(css_selector), "{} is not present".format(css_selector)
-    world.browser.find_by_css(css_selector).first.fill(text)
+def css_fill(css_selector, text, index=0, max_attempts=5):
+    assert is_css_present(css_selector)
+    attempt = 0
+    result = False
+    while attempt < max_attempts:
+        try:
+            world.browser.find_by_css(css_selector)[index].fill(text)
+            result = True
+            break
+        except WebDriverException:
+            # Occasionally, MathJax or other JavaScript can cover up
+            # an element temporarily.
+            # If this happens, wait a second, then try again
+            world.wait(1)
+            attempt += 1
+        except:
+            attempt += 1
+    assert_true(result, 'Filling {} did not work as expected'.format(css_selector))
 
 
 @world.absorb
-def click_link(partial_text):
-    world.browser.find_link_by_partial_text(partial_text).first.click()
+def click_link(partial_text, index=0, max_attempts=5):
+    attempt = 0
+    result = False
+    while attempt < max_attempts:
+        try:
+            world.browser.find_link_by_partial_text(partial_text)[index].click()
+            result = True
+            break
+        except WebDriverException:
+            # Occasionally, MathJax or other JavaScript can cover up
+            # an element temporarily.
+            # If this happens, wait a second, then try again
+            world.wait(1)
+            attempt += 1
+        except:
+            attempt += 1
+    assert_true(result, 'Clicking {} did not work as expected'.format(partial_text))
 
 
 @world.absorb
@@ -168,6 +199,21 @@ def css_text(css_selector, index=0):
 
 
 @world.absorb
+def css_value(css_selector, index=0):
+
+    # Wait for the css selector to appear
+    if world.is_css_present(css_selector):
+        try:
+            return world.browser.find_by_css(css_selector)[index].value
+        except StaleElementReferenceException:
+            # The DOM was still redrawing. Wait a second and try again.
+            world.wait(1)
+            return world.browser.find_by_css(css_selector)[index].value
+    else:
+        return ""
+
+
+@world.absorb
 def css_html(css_selector, index=0, max_attempts=5):
     """
     Returns the HTML of a css_selector and will retry if there is a StaleElementReferenceException
@@ -179,26 +225,30 @@ def css_html(css_selector, index=0, max_attempts=5):
             return world.browser.find_by_css(css_selector)[index].html
         except:
             attempt += 1
-    return ''
+    assert_true(attempt < max_attempts, 'Ran out of attempts to access {}'.format(css_selector))
 
 
 @world.absorb
 def css_has_class(css_selector, class_name, index=0, max_attempts=5):
     attempt = 0
-    found = False
-    while attempt < max_attempts and not found:
+    while attempt < max_attempts:
         try:
             return world.css_find(css_selector)[index].has_class(class_name)
-            found = True
         except:
             attempt += 1
-    return False
+    assert_true(attempt < max_attempts, 'Ran out of attempts to access {}'.format(css_selector))
 
 
 @world.absorb
-def css_visible(css_selector):
-    assert is_css_present(css_selector), "{} is not present".format(css_selector)
-    return world.browser.find_by_css(css_selector).visible
+def css_visible(css_selector, index=0, max_attempts=5):
+    assert is_css_present(css_selector)
+    attempt = 0
+    while attempt < max_attempts:
+        try:
+            return world.browser.find_by_css(css_selector)[index].visible
+        except:
+            attempt += 1
+    assert_true(attempt < max_attempts, 'Ran out of attempts to access {}'.format(css_selector))
 
 
 @world.absorb

lms/djangoapps/courseware/features/login.py

@@ -3,6 +3,7 @@
 
 from lettuce import step, world
 from django.contrib.auth.models import User
+from nose.tools import assert_true
 
 
 @step('I am an unactivated user$')
@@ -19,8 +20,15 @@ def i_am_an_activated_user(step):
 def i_submit_my_credentials_on_the_login_form(step):
     fill_in_the_login_form('email', 'robot@edx.org')
     fill_in_the_login_form('password', 'test')
-    login_form = world.browser.find_by_css('form#login-form')
-    login_form.find_by_name('submit').click()
+    attempt = 0
+    while attempt < 5:
+        try:
+            login_form = world.browser.find_by_css('form#login-form')
+            login_form.find_by_name('submit').click()
+            break
+        except:
+            attempt += 1
+    assert_true(attempt < 5, 'Login form could not be clicked')
 
 
 @step(u'I should see the login error message "([^"]*)"$')
@@ -49,6 +57,13 @@ def user_is_an_activated_user(uname):
 
 
 def fill_in_the_login_form(field, value):
-    login_form = world.browser.find_by_css('form#login-form')
-    form_field = login_form.find_by_name(field)
-    form_field.fill(value)
+    attempt = 0
+    while attempt < 5:
+        try:
+            login_form = world.browser.find_by_css('form#login-form')
+            form_field = login_form.find_by_name(field)
+            form_field.fill(value)
+            break
+        except:
+            attempt += 1
+    assert_true(attempt < 5, 'Login form could not be filled')

lms/djangoapps/courseware/features/problems.py

@@ -121,7 +121,7 @@ def reset_problem(_step):
 def press_the_button_with_label(_step, buttonname):
     button_css = 'button span.show-label'
     elem = world.css_find(button_css).first
-    assert_equal(elem.text, buttonname)
+    world.css_has_text(button_css, elem)
     world.css_click(button_css)
 
 

lms/djangoapps/courseware/features/problems_setup.py

@@ -19,6 +19,7 @@ from capa.tests.response_xml_factory import OptionResponseXMLFactory, \
     StringResponseXMLFactory, NumericalResponseXMLFactory, \
     FormulaResponseXMLFactory, CustomResponseXMLFactory, \
     CodeResponseXMLFactory
+from nose.tools import assert_true
 
 
 # Factories from capa.tests.response_xml_factory that we will use
@@ -312,14 +313,20 @@ def assert_checked(problem_type, choices):
 
     all_choices = ['choice_0', 'choice_1', 'choice_2', 'choice_3']
     for this_choice in all_choices:
-        element = world.css_find(inputfield(problem_type, choice=this_choice))
-
-        if this_choice in choices:
-            assert element.checked
-        else:
-            assert not element.checked
+        attempt = 0
+        while attempt < 5:
+            try:
+                element = world.css_find(inputfield(problem_type, choice=this_choice))
+                if this_choice in choices:
+                    assert element.checked
+                else:
+                    assert not element.checked
+                break
+            except:
+                attempt += 1
+        assert_true(attempt < 5, "Could not access {}".format(element))
 
 
 def assert_textfield(problem_type, expected_text, input_num=1):
-    element = world.css_find(inputfield(problem_type, input_num=input_num))
-    assert element.value == expected_text
+    element_value = world.css_value(inputfield(problem_type, input_num=input_num))
+    assert element_value == expected_text

lms/djangoapps/courseware/features/registration.py

@@ -11,10 +11,7 @@ def i_register_for_the_course(_step, course):
     cleaned_name = TEST_COURSE_NAME.replace(' ', '_')
     url = django_url('courses/%s/%s/%s/about' % (TEST_COURSE_ORG, course, cleaned_name))
     world.browser.visit(url)
-
-    intro_section = world.browser.find_by_css('section.intro')
-    register_link = intro_section.find_by_css('a.register')
-    register_link.click()
+    world.css_click('section.intro a.register')
 
     assert world.is_css_present('section.container.dashboard')
 

lms/djangoapps/courseware/features/signup.py

@@ -6,20 +6,38 @@ from lettuce import world, step
 
 @step('I fill in "([^"]*)" on the registration form with "([^"]*)"$')
 def when_i_fill_in_field_on_the_registration_form_with_value(step, field, value):
-    register_form = world.browser.find_by_css('form#register-form')
-    form_field = register_form.find_by_name(field)
-    form_field.fill(value)
+    attempt = 0
+    while attempt < 5:
+        try:
+            register_form = world.browser.find_by_css('form#register-form')
+            form_field = register_form.find_by_name(field)
+            form_field.fill(value)
+            break
+        except:
+            attempt += 1
 
 
 @step('I submit the registration form$')
 def i_press_the_button_on_the_registration_form(step):
-    register_form = world.browser.find_by_css('form#register-form')
-    register_form.find_by_name('submit').click()
+    attempt = 0
+    while attempt < 5:
+        try:
+            register_form = world.browser.find_by_css('form#register-form')
+            register_form.find_by_name('submit').click()
+            break
+        except:
+            attempt += 1
 
 
 @step('I check the checkbox named "([^"]*)"$')
 def i_check_checkbox(step, checkbox):
-    world.browser.find_by_name(checkbox).check()
+    attempt = 0
+    while attempt < 5:
+        try:
+            world.browser.find_by_name(checkbox).check()
+            break
+        except:
+            attempt += 1
 
 
 @step('I should see "([^"]*)" in the dashboard banner$')