User Guide

Upgrading to 2.0

Plugin support was introduced in v2.0, and if you’re upgrading from an earlier version you may need to make some changes to take advantage of any plugins. Before this version, to implement a custom wait for pages/regions to finish loading it was necessary to implement wait_for_page_to_load or wait_for_region_to_load. If you haven’t implemented either of these, you don’t need to do anything to upgrade. If you have, then whilst your custom waits will still work, we now support plugins that can be triggered after a page/region load, and these calls are made from the base classes. By overriding the default behaviour, you may be missing out on triggering any plugin behaviours. Rather than having to remember to always call the same method from the parent, you can simply change your custom wait to a new loaded property that returns True when the page/region has loaded.

So, if you have implemented your own wait_for_page_to_load() like this:

def wait_for_page_to_load(self):
    self.wait.until(lambda s: self.seed_url in s.current_url)

You will want to change it to use loaded like this:

@property
def loaded(self):
    return self.seed_url in self.selenium.current_url

Similarly, if you have implemented your own wait_for_region_to_load() like this:

def wait_for_region_to_load(self):
    self.wait.until(lambda s: self.root.is_displayed())

You will want to change it to use loaded like this:

@property
def loaded(self):
    return self.root.is_displayed()

Drivers

PyPOM requires a driver object to be instantiated, and supports multiple driver types. The examples in this guide will assume that you have a driver instance.

Selenium

To instantiate a Selenium driver you will need a WebDriver object:

from selenium.webdriver import Firefox
driver = Firefox()

Splinter

To instantiate a Splinter driver you will need a Browser object:

from splinter import Browser
driver = Browser()

Pages

Page objects are representations of web pages. They provide functions to allow simulating user actions, and providing properties that return state from the page. The Page class provided by PyPOM provides a simple implementation that can be sub-classed to apply to your project.

The following very simple example instantiates a page object representing the landing page of the Mozilla website:

from pypom import Page

class Mozilla(Page):
    pass

page = Mozilla(driver)

If a page has a seed URL then you can call the open() function to open the page in the browser. There are a number of ways to specify a seed URL.

Base URL

A base URL can be passed to a page object on instantiation. If no URL template is provided, then calling open() will open this base URL:

from pypom import Page

class Mozilla(Page):
    pass

base_url = 'https://www.mozilla.org'
page = Mozilla(driver, base_url).open()

URL templates

By setting a value for URL_TEMPLATE, pages can specify either an absolute URL or one that is relative to the base URL (when provided). In the following example, the URL https://www.mozilla.org/about/ will be opened:

from pypom import Page

class Mozilla(Page):
    URL_TEMPLATE = '/about/'

base_url = 'https://www.mozilla.org'
page = Mozilla(driver, base_url).open()

As this is a template, any additional keyword arguments passed when instantiating the page object will attempt to resolve any placeholders. In the following example, the URL https://www.mozilla.org/de/about/ will be opened:

from pypom import Page

class Mozilla(Page):
    URL_TEMPLATE = '/{locale}/about/'

base_url = 'https://www.mozilla.org'
page = Mozilla(driver, base_url, locale='de').open()

URL parameters

Any keyword arguments provided that are not used as placeholders in the URL template are added as query string parameters. In the following example, the URL https://developer.mozilla.org/fr/search?q=bold&topic=css will be opened:

from pypom import Page

class Search(Page):
    URL_TEMPLATE = '/{locale}/search'

base_url = 'https://developer.mozilla.org/'
page = Search(driver, base_url, locale='fr', q='bold', topic='css').open()

Waiting for pages to load

Whenever a driver detects that a page is loading, it does its best to block until it’s complete. Unfortunately, as the driver does not know your application, it’s quite common for it to return earlier than a user would consider the page to be ready. For this reason, the loaded property can be overridden and customised for your project’s needs by returning True when the page has loaded. This property is polled by wait_for_page_to_load(), which is called by open() after loading the seed URL, and can be called directly by functions that cause a page to load.

The following example waits for the seed URL to be in the current URL. You can use this so long as the URL is not rewritten or redirected by your application:

from pypom import Page

class Mozilla(Page):

    @property
    def loaded(self):
        return self.seed_url in self.selenium.current_url

Other things to wait for might include when elements are displayed or enabled, or when an element has a particular class. This will be very dependent on your application.

Regions

Region objects represent one or more elements of a web page that are repeated multiple times on a page, or shared between multiple web pages. They prevent duplication, and can improve the readability and maintainability of your page objects.

Root elements

It’s important for page regions to have a root element. This is the element that any child elements will be located within. This means that page region locators do not need to be unique on the page, only unique within the context of the root element.

If your page region contains a _root_locator attribute, this will be used to locate the root element every time an instance of the region is created. This is recommended for most page regions as it avoids issues when the root element becomes stale.

Alternatively, you can locate the root element yourself and pass it to the region on construction. This is useful when creating regions that are repeated on a single page.

The root element can later be accessed via the root attribute on the region, which may be necessary if you need to interact with it.

Repeating regions

Page regions are useful when you have multiple items on a page that share the same characteristics, such as a list of search results. By creating a page region, you can interact with any of these items in a common way:

The following example uses Selenium to locate all results on a page and return a list of Result regions. This can be used to determine the number of results, and each result can be accessed from this list for further state or interactions. Refer to locating elements for more information on how to write locators for your driver:

<!DOCTYPE html>
<html lang="en">
<body>
<h1>Repeated Regions Example</h1>

<ol>
    <li class="result">
        <span class="name">Result 1</span>
        <a href="./detail/1/">detail</a>
    </li>
    <li class="result">
        <span class="name">Result 2</span>
        <a href="./detail/2/">detail</a>
    </li>
    <li class="result">
        <span class="name">Result 3</span>
        <a href="./detail/3/">detail</a>
    </li>
    <li class="result">
        <span class="name">Result 4</span>
        <a href="./detail/4/">detail</a>
    </li>
</ol>

</body>
</html>
class Results(Page):
    _result_locator = (By.CLASS_NAME, 'result')

    @property
    def results(self):
        return [self.Result(self, el) for el in self.find_elements(*self._result_locator)]

    class Result(Region):
        _name_locator = (By.CLASS_NAME, 'name')
        _detail_locator = (By.TAG_NAME, 'a')

        @property
        def name(self):
            return self.find_element(*self._name_locator).text

        @property
        def detail_link(self):
            return self.find_element(*self._detail_locator).get_property("href")

Nested regions

Regions can be nested inside other regions (i.e. a menu region with multiple entry regions). In the following example a main page contains two menu regions that include multiple repeated entry regions:

<!DOCTYPE html>
<html lang="en">
<body>
<h1>Nested Regions Example</h1>
<div id="page">Main Page

    <div id="menu1" class="menu">
        <ol>
            <li class="entry">Menu1-Entry1</li>
            <li class="entry">Menu1-Entry2</li>
            <li class="entry">Menu1-Entry3</li>
            <li class="entry">Menu1-Entry4</li>
            <li class="entry">Menu1-Entry5</li>
        </ol>
    </div>
    <div id="menu2" class="menu">
        <ol>
            <li class="entry">Menu2-Entry1</li>
            <li class="entry">Menu2-Entry2</li>
            <li class="entry">Menu2-Entry3</li>
        </ol>
    </div>
</div>
</body>
</html>

As a region requires a page object to be passed you need to pass self.page when instantiating nested regions:

class MainPage(Page):

    @property
    def menu1(self):
        root = self.find_element(By.ID, "menu1")
        return Menu(self, root=root)

    @property
    def menu2(self):
        root = self.find_element(By.ID, "menu2")
        return Menu(self, root=root)


class Menu(Region):

    @property
    def entries(self):
        return [Entry(self.page, item) for item in self.find_elements(*Entry.entry_locator)]


class Entry(Region):
    entry_locator = (By.CLASS_NAME, 'entry')

    @property
    def name(self):
        return self.root.text

Shared regions

Pages with common characteristics can use regions to avoid duplication. Examples of this include page headers, navigation menus, login forms, and footers. These regions can either be defined in a base page object that is inherited by the pages that contain the region, or they can exist in their own module:

In the following example, any page objects that extend Base will inherit the header property, and be able to check if it’s displayed. Refer to locating elements for more information on how to write locators for your driver:

from pypom import Page, Region
from selenium.webdriver.common.by import By

class Base(Page):

    @property
    def header(self):
        return self.Header(self)

    class Header(Region):
        _root_locator = (By.ID, 'header')

        def is_displayed(self):
            return self.root.is_displayed()

Waiting for regions to load

The loaded property function can be overridden and customised for your project’s needs by returning True when the region has loaded to ensure it’s ready for interaction. This property is polled by wait_for_region_to_load, which is called whenever a region is instantiated, and can be called directly by functions that a region to reload.

The following example waits for an element within a page region to be displayed:

from pypom import Region

class Header(Region):

    @property
    def loaded(self):
        return self.root.is_displayed()

Other things to wait for might include when elements are displayed or enabled, or when an element has a particular class. This will be very dependent on your application.

Locating elements

Each driver has its own approach to locating elements. A suggested approach is to store your locators at the top of your page/region classes. Ideally these should be preceeded with a single underscore to indicate that they’re primarily reserved for internal use. These attributes can be stored as a two item tuple containing both the strategy and locator, and can then be unpacked when passed to a method that requires the arguments to be separated.

Selenium

The By class covers the common locator strategies for Selenium. The following example shows a locator being defined and used in a page object:

from pypom import Page
from selenium.webdriver.common.by import By

class Mozilla(Page):
    _logo_locator = (By.ID, 'logo')

    @property
    def loaded(self):
        logo = self.find_element(*self._logo_locator)
        return logo.is_displayed()

Splinter

The available locator strategies for Splinter are:

  • name
  • id
  • css
  • xpath
  • text
  • value
  • tag

The following example shows a locator being defined and used in a page object:

from pypom import Page
from selenium.webdriver.common.by import By

class Mozilla(Page):
    _logo_locator = ('id', 'logo')

    @property
    def loaded(self):
        logo = self.find_element(*self._logo_locator)
        return logo.is_displayed()

Explicit waits

For convenience, a WebDriverWait object is instantiated with an optional timeout (with a default of 10 seconds) for every page. This allows your page objects to define an explicit wait whenever an interaction causes a reponse that a real user would wait for before continuing. For example, checking a box might make a button become enabled. If we didn’t wait for the button to become enabled we may try clicking on it too early, and nothing would happen. Another example of where explicit waits are common is when waiting for pages to load or waiting for regions to load.

The following example uses Selenium to demonstrate a wait that is necessary after checking a box that causes a button to become enabled. Refer to locating elements for more information on how to write locators for your driver:

from pypom import Page
from selenium.webdriver.common.by import By

class Mozilla(Page):
    _privacy_policy_locator = (By.ID, 'privacy')
    _sign_me_up_locator = (By.ID, 'sign_up')

    def accept_privacy_policy(self):
        self.find_element(*self._privacy_policy_locator).click()
        sign_me_up = self.find_element(*self._sign_me_up_locator)
        self.wait.until(lambda s: sign_me_up.is_enabled())

You can either specify a timeout by passing the optional timeout keyword argument when instantiating a page object, or you can override the __init__() method if you want your timeout to be inherited by a base project page class.

Note

The default timeout of 10 seconds may be considered excessive, and you may wish to reduce it. It it not recommended to increase the timeout however. If you have interactions that take longer than the default you may find that you have a performance issue that will considerably affect the user experience.