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Write clean Selenium tests in Django

Project description

Write clean Selenium tests on Django. Works on Python 2.7 and 3. Uses a paradigm similar to what has confusingly been dubbed “page object pattern”.

Tutorial

Installation

In your virtualenv:

pip install django-selenium-clean

Setting up

  • Create a new django project and app:

    django-admin startproject foo
    cd foo
    python manage.py startapp bar
  • In foo/settings.py, add 'bar' to INSTALLED_APPS

  • In foo/urls.py, add from bar.views import SimpleView to the top, and add url(r'^$', SimpleView.as_view()) to urlpatterns.

  • Add the SimpleView to bar/views.py:

    import textwrap
    
    from django.http import HttpResponse
    from django.views.generic.base import View
    
    
    class SimpleView(View):
    
        def dispatch(request, *args, **kwargs):
            response_text = textwrap.dedent('''\
                  <html>
                  <head>
                  <title>Greetings to the world</title>
                  </head>
                  <body>
                  <h1 id="earth">Greetings to earth</h1>
                  <h1 id="world" style="display: none;">Hello, world!</h1>
    
                  <p>We have some javascript here so that when you click the button
                     the heading above toggles between "Greetings to earth" and
                     "Hello, world!".</p>
    
                  <button onclick="toggle()">Toggle</button>
    
                  <script type="text/javascript">
                     toggle = function () {
                        var heading_earth = document.getElementById("earth");
                        var heading_world = document.getElementById("world");
                        if (heading_earth.style.display == 'none') {
                              heading_world.style.display = 'none';
                              heading_earth.style.display = 'block';
                        } else {
                              heading_earth.style.display = 'none';
                              heading_world.style.display = 'block';
                        }
                     }
                  </script>
                  </body>
                  </html>
            ''')
            return HttpResponse(response_text)

We’re done setting up. If you now run python manage.py runserver in your browser and visit http://localhost:8000/ in your browser, you should see the simple page. Let’s now proceed to write a test for it.

Writing the test

Modify bar/tests.py so that it has the following contents:

from unittest import skipUnless

from django_selenium_clean import selenium, SeleniumTestCase, PageElement
from selenium.webdriver.common.by import By


@skipUnless(selenium, "Selenium is unconfigured")
class HelloTestCase(SeleniumTestCase):

    heading_earth = PageElement(By.ID, 'earth')
    heading_world = PageElement(By.ID, 'world')
    button = PageElement(By.CSS_SELECTOR, 'button')

    def test_toggle(self):
        # Visit the page
        selenium.get(self.live_server_url)

        # Check that the world heading is visible
        self.assertTrue(self.heading_earth.is_displayed())
        self.assertFalse(self.heading_world.is_displayed())

        # Toggle and check the new condition
        self.button.click()
        self.heading_world.wait_until_is_displayed()
        self.assertFalse(self.heading_earth.is_displayed())
        self.assertTrue(self.heading_world.is_displayed())

        # Toggle again and re-check
        self.button.click()
        self.heading_earth.wait_until_is_displayed()
        self.assertTrue(self.heading_earth.is_displayed())
        self.assertFalse(self.heading_world.is_displayed())

Executing the test

Try python manage.py test and it will skip the test because selenium is unconfigured. You need to configure it by specifying SELENIUM_WEBDRIVERS in foo/settings.py:

from selenium import webdriver
SELENIUM_WEBDRIVERS = {
    'default': {
        'callable': webdriver.Firefox,
        'args': (),
        'kwargs': {},
    }
}

Now try again, and it should execute the test.

Advanced test running tricks

Executing a test in many widths

Add this to your foo/settings.py:

SELENIUM_WIDTHS = [1024, 800, 350]

This will result in executing all SeleniumTestCase’s three times, one for each specified browser width. Useful for responsive designs. The default is to run them on only one width, 1024.

Using many selenium drivers

You can have many SELENIUM_WEBDRIVERS:

from selenium import webdriver
SELENIUM_WEBDRIVERS = {
    'default': {
        'callable': webdriver.Firefox,
        'args': (),
        'kwargs': {},
    }
    'chrome': {
        'callable': webdriver.Chrome,
        'args': (),
        'kwargs': {},
    }
}

By default, the default one is used. You can specify another using the SELENIUM_WEBDRIVER environment variable:

SELENIUM_WEBDRIVER=chrome python manage.py test

Running a headless browser

It can be very useful to run the selenium tests with a headless browser, that is, in an invisible browser window. For one thing, it is much faster. There are also other use cases. This can be done on operating systems supporting xvfb. Install xvfb and pyvirtualdisplay; for example:

apt-get install xvfb
pip install pyvirtualdisplay

Add this to your settings.py:

if os.environ.get('SELENIUM_HEADLESS', None):
    from pyvirtualdisplay import Display
    display = Display(visible=0, size=(1024,768))
    display.start()
    import atexit
    atexit.register(lambda: display.stop())

Then run the tests like this:

SELENIUM_HEADLESS=True python manage.py test

Reference

The selenium object

from django_selenium_clean import selenium

Technically, selenium is a wrapper around the selenium driver. In practice, you can think about it as the browser, or as the equivalent of Django’s test client. It has all selenium driver attributes and methods, but you will mostly use get(). It also has the following additional methods:

  • selenium.login(**credentials)`, `selenium.logout()

    Similar to the Django test client login() and logout() methods. login() returns True if login is possible; False if the provided credentials are incorrect, or the user is inactive, or if the sessions framework is not available.

  • selenium.wait_until_n_windows(n, timeout=2)

    Useful when a Javascript action has caused the browser to open another window. The typical usage is this:

    button_that_will_open_a_second_window.click()
    selenium.wait_until_n_windows(n=2, timeout=10)
    windows = selenium.window_handles
    selenium.switch_to_window(windows[1])
    # continue testing

    If the timeout (in seconds) elapses and the number of browser windows never becomes n, an AssertionError is raised.

SeleniumTestCase objects

from django_selenium_clean import SeleniumTestCase

SeleniumTestCase is the same as Django’s StaticLiveServerTestCase but it adds a little bit of Selenium functionality. Derive your Selenium tests from this class instead of StaticLiveServerTestCase.

PageElement objects

from django_selenium_clean import PageElement

PageElement is a lazy wrapper around WebElement; it has all its properties and methods. It is initialized with a locator, but the element is not actually located until needed. In addition to WebElement properties and methods, it has these:

  • PageElement.exists(): Returns True if the element can be located.

  • PageElement.wait_until_exists(timeout=10)

    PageElement.wait_until_not_exists(timeout=10)

    PageElement.wait_until_is_displayed(timeout=10)

    PageElement.wait_until_is_not_displayed(timeout=10)

    PageElement.wait_until_contains(text, timeout=10)

    PageElement.wait_until_not_contains(text, timeout=10)

    What these methods do should be self-explanatory from their name. The ones ending in contains refer to whether the element contains the specified text. The methods raise an exception if there is a timeout.

License

Licensed under the BSD 3-clause license; see LICENSE.txt for details.

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