5. Controller

5.1. About

Controllers were created to utilize our defined components and to farm out tedious rudimentary tasks such as navigating and managing our context. Controllers allow us to define our logic in a behavioral manner, outside of our test cases, keeping everything clean, simple, and manageable. Controllers also allow us to reference a browser once and pass it to all of our defined components. Reference: Page Object Model

There are a vast other quirks to using the controller, component architecture – such as:

  • Simple exportable client packages for larger suites (multi-application end to end tests).
  • Clean tests; no need for instance-hacks.
  • Maintainability, easily documentable.
  • Application/website state management.

5.2. Best Practices

Following this architectural pattern (controller, component) your controller not contain any accessory methods to search for or provide elements. This class of functionality should be handled exclusively by your defined components.

If you haven’t already check out Getting Started for examples.

5.3. Polyfills

Believe it or not, each webdriver for each major browser is maintained by their respective company. Selenium offers an api and a spec that these companies simply adhere to, which is what allows the selenium bindings to conformally speak to any of your desired browsers (for the most part). When a controller instance is instantiated, it will consume the webdriver passed and monkey patch operations and or functions for equality.

The most prevelant polyfill featured is uniformity for find_elements_by_x. Every webdriver, but Safari (of course), will return an empty list as where Safari’s will raise an ElementNotFoundException.

Any irregularities between webdrivers should be reported via the py-component-controller github with steps to reproduce and a related issue or task if available for the corresponding webdriver.

5.4. Logging

The controller supports logging out of the box. Three settings may be toggled to better exercise the logger:

  • _FILTER_SELENIUM_LOGS_: Filters selenium logs all together.
  • _FILTER_SELENIUM_LOG_STREAM_: Filters selenium logs from stdout stream.
  • _LOG_TO_FILE_: Drop logs to hard disk. Will drop individual logs for the controller and selenium.

These settings are all disabled by default, but can be toggled like so:

… code-block:: python

from pyscc import Controller

class App(Controller):

_LOG_TO_FILE_ = True …

To filter logs, refer to the api method add_filter which can be accessed via the controller’s logger instance.

… code-block:: python

# filter messages containing the text ‘selenium’ ref.controller.logger.add_filter(lambda msg: ‘selenium’ in msg)

5.5. Attributes

When a controller is instantiated, the constructor automatically binds the following attributes:

  • browser: Webdriver consumed in the constructor.
  • js: Reference to instantiated pyselenium-js driver.
  • logger: Python logger reference.
  • components Resource for instantiated components constructed using the dictionarty provided in the constructor.
  • env: Resource for environmental variables consumed in the form of kwargs from the constructor.

5.6. Adding Services

Services are defined in more detail here.

To add a new service to your controller, refer to the api method add_service:

from pyscc import Service

class UserService(Service):

    def login(self, username, password):
        # can create methods using the same context as a controller
        login_page = self.components.login

controller.add_service('users', UserService)

5.7. Getting Current Location

The controller provides a property navigation that can be referenced to fetch your webdriver’s current location.

>> http://github.com

5.8. Getting Current Page Title

Refer to the controller’s title property to pull the current page title from your webdriver.

>> Github

5.10. Checking Location

To check against your webdriver’s current location, you can use the is_location method:

# check if the route is in your webdrivers location

# strict check on absolute location
controller.is_location('https://github.com/neetjn/py-component-controller', strict=True)

# timed location check, will check every second until condition met or timeout exceeded
controller.is_location('/neetjn/py-component-controller', timeout=5)

# error if condition is not met
controller.is_location('/neetjn/py-component-controller', timeout=5, error=True)
controller.is_location('/neetjn/py-component-controller', timeout=5,
    error='Expected to be on py-component-controller repository page')

# alternatively format provided error message
controller.is_location('/neetjn/py-component-controller', timeout=5,
    error='Expected to be on ${expected} found ${found}')

# check against a list of possible routes
controller.is_location('/neetjn/pyselenium-js', '/neetjn/py-component-controller')

5.11. Switching to Window by Title

For window management, the controller provides a method that allows you to switch to a window by title:

# partial window title check
>> True, False

# strict window title check
controller.window_by_title('readthedocs - My Docs', strict=True)
>> True, False

# polling for window by title
controller.window_by_title('readthedocs', timeout=5)
>> True, False

# error if condition is not met
controller.window_by_title('readthedocs', timeout=5, error=True)
controller.window_by_title('readthedocs', timeout=5,
    error='Could not find the expected readthedocs window')

# alternatively format error message
controller.window_by_title('readthedocs', timeout=5,
    error='Could not find the window by title ${expected} found ${found}')

5.12. Switching to Window by Location

The controller also provided a method that allows you to switch to a window by location:

# partial window location check
>> True, False

# strict window location check
controller.window_by_location('https://readthedocs.io/neetjn', strict=True)
>> True, False

# poll for window by location
controller.window_by_location('readthedocs.io', timeout=5)
>> True, False

# error if condition is not met
controller.window_by_location('readthedocs.io', timeout=5, error=True)
controller.window_by_location('readthedocs.io', timeout=5,
    error='Could not find the expected readthedocs window')

# alternatively format error message
controller.window_by_location('readthedocs.io', timeout=5,
    error='Could not find the window by location ${expected} found ${found}')

5.13. Conditional Waits

Unlike the official selenium bindings, the controller allows an interface for an all-purpose general conditional wait.

# wait 5 seconds for element to be visible
# you may pass any callable object as a condition that returns a truthy value
controller.wait(timeout=5, condition=element.check.visible)

# wait for 10 seconds for window to be available with the title "Github"
    condition=lambda: controller.window_by_title('Github'))
>> True, False

# by design the wait will ignore any exceptions raised while checking the condition
# for debugging purposes, you may toggle the throw_error flag to raise the last error
controller.wait(timeout=5, throw_error=True, condition=lambda: 0/0)

# you may toggle the reverse flag to check for a falsy value
controller.wait(timeout=5, reverse=True, condition=element.check.invisible)

5.14. Take a Screenshot

To take a screenshot and drop it to your host machine, use the screen_shot method:


The screenshot prefix is optional, but this method will automatically generate a unique file name to deter from any io errors and preserve your artifacts.

5.15. Get Browser Console Logs

Using pyselenium-js under the hood we can log our browser’s console output. To initialize the logger, you can reference the console_logger method from the controller’s js attribute (pysjs reference). Once you’ve initialized the logger, use the controller api method browser_logs to drop your logs to your host machine.

# initialize logger

# dump browser console logs

# dump browsers logs with a log name

5.16. Terminate Webdriver Session

Equipped with the controller is an all-webdriver termination mechanism. This can be especially helpful for provisioned environments using both local and remote webdrivers.