Taming WebApp Testing Complexity

Posted on February 3, 2017 by Vincent Engelmann

The Page Object “pattern” allows us to clean up tests, enhance logging, reuse utilities, and tame complexity.

Representing Pages

The page representation consists of a Page superclass and any subclass with a name that resembles the page it describes. For example, if you have a login page, you can describe it as:

class Login(Page):
    def __init__():
        self.username = TextArea(id_="username", "username field")
        self.password = TextArea(id_="passwd", "password field")
    def set_username(username):
        return self
    def set_password(pw):
        return self
        TextArea(id_="username", "username field")

The Page superclass has the primary responsibility of ensuring all pages use the same wdhelper singleton for all Selenium actions.

class Page(object):
    def __init__():
        self.wdhelper wdhelper

Session Consistency Across Objects

The WdHelper singleton maintains the WebDriver session across all pages and elements.

Representing DOM Elements

from selenium.webdriver.remote.webelement import WebElement
from src.poutils import jsutil
from src.poutils import wdhelper

class E(object):

    Represents a generic HTML element.


    def __init__(self, css=None, xpath=None, id_=None, description):
        self.selector_type = None
        self.selector = None
        self.description = description
        if css is None and xpath is None and id_ is None:
            raise Exception("You must specify either css, xpath, or ID selector.")

    def _wait_for(wait_type: WaitType, timeout: int) -> WebElement:

    def click(timeout=None, auto_scroll=False):
        self.element = self._wait_for(WaitType.CLICKABLE, timeout)
        if auto_scroll:

    def get_text(timeout=None):
        self._wait_for(WaitType.PRESENT, timeout)

We used inheritance to make intent clearer and keep things maintainable:

class TextArea(E):
    def __init__(*args, **kwargs):
        E.__init__(self, *args, **kwargs)

    def get_text(timeout=None):
        Overrides the E class's `get_text()` method. Extracts
        the text from an HTML TextArea element.
        self.element = self._wait_for(WaitType.PRESENT, timeout)
        return self.element.text 

    def enter_text(text: str, timeout=None) -> 'TextArea':
        self.element = self._wait_for(WaitType.PRESENT, timeout)

We can re-use E’s methods, implement different behaviors for common actions, and add additional actions appropriate to the element type. WaitType is an Enum.