Advanced techniques for Web functional testing

Julien Phalip

Definitions

• Unit testing
  • Ensure that small parts work in isolation
• Integration testing
  • Ensure those poarts work well together
• Functional Testing
  • ensure applcation functions well, especially from the user's perspective

Selenium

• Uses WebDriver API: soon to become W3C standard
• Works across multip browsers
• Client libraries in many languages
• easy install

Testing responsive sites

    self.driver.set_window_size(600, 600)
    self.driver.set_window_size(1280, 800)

Testing visuals with Needle

• bfirsh/needle
• based on selenium
• catch regressions with styles, typography, SVG, images etc. by coparing screenshots

    self.assertScreenshot(
        '.banner',  # CSS selector
        'banner'    # filename (PNG)
    )

• First time you run the test, pass a flag to tell Needle to save the screen shot

    $ nosetests tests:BannerTest --with-save-baseline

• Helps you check for CSS changes
• creates a visual diff image... cooooool!

Tips

• Baseline screenshots == Fixtures
  • Store them in your repo
• ensure consistency between environments to avoid false positives
  • browser version, fonts, etc.
  • Use configuration management!

Continuous Integration

Headless browsers

• Xvfb
  • $ xvfb --run # run next command in the virtual framebuffer
• PyVirtualDisplay
• PhantomJS

Sauce Labs

• run remotely in the cloud
• gives access to multiple browsers and multiple platforms
• parallel tests
• video recording of all sessions

Speed and Robustness

Optimizing for speed

• use PhantomJS (headless mode)
• Use parallelization
  • nostests --processes=10

Optimizing for robustness

• Pin down versions for your whole software stack, including the browser
• Master the use of explicit waits, esp. with heavy JS/Ajax apps

Resources

• The Selenium Guidebook
• Selenium Testing Tools Cookbook

A Word of Caution

• Integration & Functional tests are slow; use them with moderation
• use selenium only for what a dummy test client may not already achieve

Integration frontend/backend

• ensure that the user interface rworks
• have fun in the process and functional test are important
• increase confidence
• increase test coverage