Automating Django Functional Tests Using Selenium on Cloud

Automating Django
FunctionalTests Using
Selenium on Cloud
Jonghyun Park, Lablup Inc.
2016/08/14 (Sun) @PyCon APAC 2016

Contents and target audience
•How to functional tests on Django
using Selenium.
• Running functional tests automatically on AWS EC2.
• And some tips on writing functional tests (if time permits).
• Target audience
• Python beginners - intermediates.
• Who have written some tests in Python/Django
• … but not much.

About speaker
• Physics (~4 yr)
• Single-molecule Biophysics (~8 yr)
• Optical microscope
• DNA, protein
• IT newbie (~1.2 yr)
• HTML, CSS, Javascript, Polymer (Google)
• Python-Django

About speaker
CodeOnWeb (codeonweb.com)

CodeTest
General remarks about code testing
Tests on CodeOnWeb

Test code
• Code that tests code.
def login(username, password, ...):
...
if success: return True
else: return False
def test_login():
result = login('test', '1' , ...)
assertTrue(result)
Test
login.py
test_login.py

Why tests code?
• How do we know our code is okay even if we are
messing around all the parts of the code?
• Ensure minimal code integrity when refactoring.
• Man cannot test all features by hand.
• Pre-define requirements for a feature.

Test-Driven Development (TDD)
https://goo.gl/IPwERJ
Some people actually do!

Writing tests is good for newbie
• Can understand the logic of each function/module
• … w/o destroying real service whatever you do.
• Defeat bugs & improves codes, if you are lucky.
https://goo.gl/sU2D2M
There are stupid codes, but not stupid test codes!
like me

Kinds of tests for CodeOnWeb
• Unit tests
• Test of independent unit of behavior.
• e.g., function, class method.
• Test layer: model / form / view.
• Functional tests
• Test of independent piece of functionality.
• May test many functions or methods.
• Test of actual user interaction on the web browser.
lenium

Using Selenium
Functional testing using selenium with Django

Selenium
• Browser emulator.
• Automate user interaction
on the browser.
• Can be utilized for testing
… and other things.
python manage.py test
functional_tests.test_login_registration
.LoginTest
Browser (Firefox, Chrome, …)
Selenium
Webdriver

Test scheme using Selenium
Install Selenium
pip install selenium
Get browser through webdriver
browser = webdriver.Firefox()
Visit web page
browser.get(url)
Do whatever you want Test response is expected
browser.find_element_by_id(
'lst-ib').send_keys('haha')
self.assertEqual(...)
self.assertTrue(...)

Example: automating googling
import time
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
# Get browser through webdriver
# Visit Google!
browser.get('https://google.com/')
# Enter keyword and enter
inp = browser.find_element_by_id('lst-ib')
inp.send_keys('PyCon 2016')
inp.send_keys(Keys.RETURN)
# Just wait a little
time.sleep(3)
# Close browser window
browser.quit()
python functional_tests/test_pycon_google1.py
This is not a test case!

Convert to Django’s test case
import time
from django.contrib.staticfiles.testing import StaticLiveServerTestCase
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
class GoogleTest(StaticLiveServerTestCase):
def setUp(self):
self.browser = webdriver.Firefox()
self.browser.set_window_size(1024, 768)
def tearDown(self):
time.sleep(3)
self.browser.quit()
def test_google_search(self):
self.browser.get('https://google.com/')
inp = self.browser.find_element_by_id('lst-ib')
inp.send_keys('PyCon 2016')
inp.send_keys(Keys.RETURN)
live django server
+ collect static files
python functional_tests/test_pycon_google2.py(X)
python manage.py test functional_tests.test_pycon_google2(O)

Finding elements
browser.find_element_by_id('loginForm')
.find_element_by_css_selector('input[name="username"]')
.find_element_by_name('username')
.find_element_by_class_name('login')
.find_element_by_tag_name('input')
.find_element_by_tag_link_text('Go to Google')
.find_element_by_tag_partial_link_text('Go to')
.find_element_by_xpath('//form[@id=" loginForm "]')
<html>
<body>
<form id="loginForm" class="login">
<input name="username" type="text" />
<input name="password" type="password" />
<input name="continue" type="submit" value="Login" />
</form>
<a href=”https://google.com/">Go to Google</a>
</body>
<html>
browser.find_elements_by_id('loginForm')
...

Interacting with elements
item = browser.find_element_by_id('entry-item')
item.click()
ui_type = item.get_attribute('ui-type')
browser.execute_script(
'arguments[0].setAttribute("disabled", "true")',
item,
)
browser.execute_script(
'arguments[0].querySelector("paper-menu").selected = arguments[1]',
item, '2'
)
Not that difficult if you know Javascript.

Let’s write a login test
def test_user_login(self):
# Store login count of the user
user = get_user_model().objects.get(username='einstein')
logincount = user.profile.logincount
# visit root url ('/')
self.browser.get(self.live_server_url)
# Try to login with email and password
self.browser.find_element_by_name('email').send_keys('einstein@lablup.com')
self.browser.find_element_by_name('password').send_keys('1')
self.browser.find_element_by_css_selector('fieldset paper-button').click()
# Confirm login count is increased by 1
self.assertEqual(user.profile.logincount, logincount + 1)
# Check visit correct url
target_url = self.live_server_url + '/accounts/profile/usertype/'
self.assertEqual(self.browser.current_url, target_url)
python manage.py test functional_tests.test_pycon_login

Waits in Selenium
Waiting is very important

Selenium, the beauty of waiting
• Wait what?
• Page loading
• Elements loading
• Elements visibility
• Ajax response
• DB operation
• …
https://goo.gl/5ykwc4

Broken login example
# visit root url ('/')
# Try to login with email and password
self.browser.find_element_by_name('email').send_keys('einstein@lablup.com')
self.browser.find_element_by_name('password').send_keys('1')
self.browser.find_element_by_css_selector('fieldset paper-button').click()
# Confirm login count is increased by 1
# Check visit correct url
target_url = self.live_server_url + '/accounts/profile/usertype/'
python manage.py test functional_tests.test_pycon_login

Selenium do not wait
automatically
login.html
submit()
views.py
…
user.profile.logincount += 1
user.profile.save()
...
render logged_in.html
logged_in.html
test_pycon_login.py
user.profile.logincount Which one is faster?

Selenium do not wait
automatically
browser.get("http://www.google.com")
Dependent on several factors, including the
OS/Browser combination, WebDriver may
or may not wait for the page to load.

Waiting methods in Selenium
• Implicit wait
• Explicit wait
• Stupid wait
• It is highly un-recommended to wait for specific
amounts of time.
• If target is loaded in 5 s, we waste the remaining time.
• If target is not loaded in 5 s, the test fails (slow system).
import time
time.sleep(5)
Provided by Selenium

Implicit wait
• Official DOC:
• Easy to use, global effect.
• Applies only for element waiting.
An implicit wait is to tell WebDriver to poll the DOM for a certain amount
of time when trying to find an element or elements if they are not
immediately available.The default setting is . Once set, the implicit wait is
set for the life of theWebDriver object instance.
browser.implicitly_wait(10) # in seconds
browser.get("http://somedomain/url_that_delays_loading")
myDynamicElement = browser.find_element_by_id("myDynamicElement")

Implicit wait
• Waiting behavior is determined on the “remote”
side of the webdriver.
• Different waiting behavior
on different OS, browser,
versions, etc.
• Return element immediately
• Wait until timeout
• …
def implicitly_wait(self, time_to_wait):
self.execute(Command.IMPLICIT_WAIT, {'ms': float(time_to_wait) * 1000})
WebDriver RemoteConnection.execute()
Selenium
Webdriver

Explicit wait
• Official DOC:
• A little messy, local effect.
An explicit wait is code you define to wait for a certain condition to occur
before proceeding further in the code. …WebDriverWait in combination with
ExpectedCondition is one way this can be accomplished.
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
import selenium.webdriver.support.expected_conditions as EC
ff = webdriver.Firefox()
ff.get("http://somedomain/url_that_delays_loading")
try:
element = WebDriverWait(ff, 10).until(
EC.presence_of_element_located((By.ID, "myDynamicElement"))
)
finally:
ff.quit()

Explicit wait
• Highly flexible (variety of expected conditions)
EC.title_is(...)
.title_contains(...)
.presence_of_element_located(...)
.visibility_of_element_located(...)
.visibility_of(...)
.presence_of_all_elements_located(...)
.text_to_be_present_in_element(...)
.text_to_be_present_in_element_value(...)
.frame_to_be_available_and_switch_to_it(...)
.invisibility_of_element_located(...)
.element_to_be_clickable(...)
.staleness_of(...)
.element_to_be_selected(...)
.element_located_to_be_selected(...)
.element_selection_state_to_be(...)
.element_located_selection_state_to_be(...)
.alert_is_present(...)

Explicit wait
• Highly flexible (not limited for waiting element)
• Waiting is controlled on the “local” side.
• Defined behavior. def until(self, method, message=''):
end_time = time.time() + self._timeout
while(True):
try:
value = method(self._driver)
if value:
return value
except self._ignored_exceptions:
pass
time.sleep(self._poll)
if(time.time() > end_time):
break
raise TimeoutException(message)
condition = lambda _: self.browser.execute_script('return document.readyState') == 'complete'
WebDriverWait(self.browser, 30).until(condition)
Selenium
Webdriver

Use explicit wait
• Use explicit wait!
• In good conditions (OS, browser, version), implicit
wait can simplify test codes.
• Be aware that the condition may change in the future.
• I think implicit wait is not very stable way to go.
• Never use stupid wait.
• Except in a very limited cases (like presentation?).

RunningTests on Cloud
(AWS EC2)
Functional tests: automatically once a day

Run selenium on AWS
• No screen
• Virtual display
• Slow machine (low cost)
• Give timeout generously
• That’s all!

Run selenium on AWS
# Install headless java
sudo apt-get install openjdk-6-jre-headless
# Fonts
sudo apt-get install xfonts-100dpi xfonts-75dpi xfonts-scalable xfonts-cyrillic
# Headless X11 magic is here
sudo apt-get install xvfb
# We still demand X11 core
sudo apt-get install xserver-xorg-core
# Firefox installation
sudo apt-get install firefox
# Download Selenium server
wget http://selenium.googlecode.com/files/selenium-server-standalone-2.31.0.jar
# Run Selenium server
Xvfb :0 -screen 0 1440x900x16 2>&1 >/dev/null &
export DISPLAY=:0
nohup xvfb-run java -jar selenium-server-standalone-2.53.0.jar > selenium.log &
http://goo.gl/GRbztO
+ crontab

Test automation for CodeOnWeb
Unit tests
Functional tests
Local1
Test server (on EC2)
git commit; git push
Actual codes
Github
Github-Auto-Deploy
(listen hook run scripts)
hook
git pull
post-merge hook
Run DB migration
Run unit tests
listen
err no err
Error posting script
Run functional tests
errno err
Unit tests
Functional tests
Local2
git commit; git push
Actual codes
once a day
comment on issue
…

Slack integration is also possible

SomeTips
Most of them is on the web.

Faster password hasher
• Use fastest password hasher (MD5) in testing.
• Django’s default: PBKDF2 algorithm with SHA256 hash.
• It’s more secure, but quite slow.
• In our case, this reduces the test running time by
• half (for unit tests).
• ~10% (for functional tests).
• Never use this in production server.
PASSWORD_HASHERS = [
'django.contrib.auth.hashers.MD5PasswordHasher',
]
settings.py

Shorter login
from django.conf import settings
from django.contrib.auth import get_user_model, BACKEND_SESSION_KEY,
SESSION_KEY, HASH_SESSION_KEY
from django.contrib.sessions.backends.db import SessionStore
def login_browser(self, username='einstein'):
# Set fake session
user = get_user_model().objects.get(username=username)
session = SessionStore()
session[SESSION_KEY] = user.pk
session[BACKEND_SESSION_KEY] = 'django.contrib.auth.backends.ModelBackend'
session[HASH_SESSION_KEY] = user.get_session_auth_hash()
session.save()
# To set cookies, the browser should visit a page (due to same origin policy).
# It is faster to visit dummy page than login page itself.
self.browser.get(self.live_server_url + '/selenium_dummy')
self.browser.add_cookie({
'name': settings.SESSION_COOKIE_NAME,
'value': session.session_key,
'secure': False,
'path': '/'
})
Tests for logged-in user is requred.

Fluently wait
• Wait for page load.
class CommonMethods:
@contextmanager
def wait_for_page_load(self, timeout=TIMEOUT):
old_element = self.browser.find_element_by_tag_name('html')
yield
WebDriverWait(self.browser, timeout).until(EC.staleness_of(old_element))
# Wait until ready state is complete
self.wait_until(
lambda _: self.browser.execute_script('return document.readyState') == 'complete'
)
...
with self.wait_for_page_load():
self.browser.get(self.live_server_url + '/dashboard/entry/'
self.browser.get(self.live_server_url + '/dashboard/entry/')
?

Fluently wait
• Simpler explicit wait.
...
def wait_until(self, condition):
WebDriverWait(self.browser, TIMEOUT).until(condition)
element = self.wait_until(
EC.element_to_be_clickable((By.ID, 'myDynamicElement'))
)
element = WebDriverWait(ff, 10).until(
EC.presence_of_element_located((By.ID, "myDynamicElement"))
)

Make your own useful scripts
...
def clear_input(self, element):
self.browser.execute_script('arguments[0].value = ""', element)
def click_button(self, element):
self.browser.execute_script('arguments[0].click()', element)
self.clear_input(self.elm['email_input'])
Using send_keys(str) appends str, not replacing
Using selenium’s click() sometimes not working (animated buttons, …)
self.click_button(self.elm['submit_button'])

Separate page implementation
from test codes
CommonMethods
WebPageBase FunctionalTestBase
LogInPage
SignupPage
…
LogInTest
SignupProcessTest
…
/accounts/login/
/accounts/signup/

Web page classes
class LogInPage(WebPageBase):
def __init__(self, browser):
super(LogInPage, self).__init__(browser)
self.elm.update({
'email_input': browser.find_element_by_name('email'),
'pwd_input': browser.find_element_by_name('password'),
'submit_button': browser.find_element_by_css_selector('fieldset paper-button'),
...
})
def login(self, email, password):
self.elm['email_input'].send_keys(email)
self.elm['pwd_input'].send_keys(password)
self.click_button(self.elm['submit_button'])
def click_signup_button(self):
self.click_button(self.elm['signup_link'])
def click_forgot_password_button(self):
self.click_button(self.elm['forgot_pwd'])
class SignUpPage(WebPageBase):
...
pre-define static elements
modularize representative features

Test classes using web page
classes
class LoginTest(FunctionalTestBase):
# Visit login page and login
login_page = LogInPage(self.browser)
login_page.login('einstein@lablup.com', '0000')
# Check login count is increased by 1
# Check expected url
target_url = self.live_server_url + '/dashboard/'
class SignupProcessTest(FunctionalTestBase):
def test_user_signup(self):
# User clicks signup button at login page
login_page = LogInPage(self.browser)
login_page.click_signup_button()
...
use web page classes / methods

Summary
• Using Selenium for Django functional tests.
• Wait is important in Selenium.
•Use explicit wait.
• Automate tests on AWS EC2.
• Give structure to your tests.
• Make your useful scripts.

Thank you!
• Staffs of APAC PyCon 2016
• … And ALL ofYOU!
http://www.lablup.com/
https://codeonweb.com/
https://kid.codeonweb.com/

Automating Django Functional Tests Using Selenium on Cloud

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