2. Getting Started

2.1. Simple Usage

If you have installed Selenium Python bindings, you can start using it from Python like this.

from selenium import webdriver
from selenium.webdriver.common.keys import Keys

driver = webdriver.Firefox()
driver.get("http://www.python.org")
assert "Python" in driver.title
elem = driver.find_element_by_name("q")
elem.clear()
elem.send_keys("pycon")
elem.send_keys(Keys.RETURN)
assert "No results found." not in driver.page_source
driver.close()

The above script can be saved into a file (eg:- python_org_search.py), then it can be run like this:

python python_org_search.py

The python which you are running should have the selenium module installed.

2.2. Example Explained

The selenium.webdriver module provides all the WebDriver implementations. Currently supported WebDriver implementations are Firefox, Chrome, IE and Remote. The Keys class provide keys in the keyboard like RETURN, F1, ALT etc.

from selenium import webdriver
from selenium.webdriver.common.keys import Keys

Next, the instance of Firefox WebDriver is created.

driver = webdriver.Firefox()

The driver.get method will navigate to a page given by the URL. WebDriver will wait until the page has fully loaded (that is, the “onload” event has fired) before returning control to your test or script. It’s worth noting that if your page uses a lot of AJAX on load then WebDriver may not know when it has completely loaded.:

driver.get("http://www.python.org")

The next line is an assertion to confirm that title has “Python” word in it:

assert "Python" in driver.title

WebDriver offers a number of ways to find elements using one of the find_element_by_* methods. For example, the input text element can be located by its name attribute using find_element_by_name method. Detailed explanation of finding elements is available in the Locating Elements chapter:

elem = driver.find_element_by_name("q")

Next we are sending keys, this is similar to entering keys using your keyboard. Special keys can be sent using Keys class imported from selenium.webdriver.common.keys. To be safe, we’ll first clear any prepopulated text in the input field (e.g. “Search”) so it doesn’t affect our search results:

elem.clear()
elem.send_keys("pycon")
elem.send_keys(Keys.RETURN)

After submission of the page, you should get the result if there is any. To ensure that some results are found, make an assertion:

assert "No results found." not in driver.page_source

Finally, the browser window is closed. You can also call quit method instead of close. The quit will exit entire browser whereas close` will close one tab, but if just one tab was open, by default most browser will exit entirely.:

driver.close()

2.3. Using Selenium to write tests

Selenium is mostly used for writing test cases. The selenium package itself doesn’t provide a testing tool/framework. You can write test cases using Python’s unittest module. The other options for a tool/framework are py.test and nose.

In this chapter, we use unittest as the framework of choice. Here is the modified example which uses unittest module. This is a test for python.org search functionality:

import unittest
from selenium import webdriver
from selenium.webdriver.common.keys import Keys

class PythonOrgSearch(unittest.TestCase):

    def setUp(self):
        self.driver = webdriver.Firefox()

    def test_search_in_python_org(self):
        driver = self.driver
        driver.get("http://www.python.org")
        self.assertIn("Python", driver.title)
        elem = driver.find_element_by_name("q")
        elem.send_keys("pycon")
        elem.send_keys(Keys.RETURN)
        assert "No results found." not in driver.page_source


    def tearDown(self):
        self.driver.close()

if __name__ == "__main__":
    unittest.main()

You can run the above test case from a shell like this:

python test_python_org_search.py
.
----------------------------------------------------------------------
Ran 1 test in 15.566s

OK

The above result shows that the test has been successfully completed.

2.4. Walk through of the example

Initially, all the basic modules required are imported. The unittest module is a built-in Python based on Java’s JUnit. This module provides the framework for organizing the test cases. The selenium.webdriver module provides all the WebDriver implementations. Currently supported WebDriver implementations are Firefox, Chrome, Ie and Remote. The Keys class provide keys in the keyboard like RETURN, F1, ALT etc.

import unittest
from selenium import webdriver
from selenium.webdriver.common.keys import Keys

The test case class is inherited from unittest.TestCase. Inheriting from TestCase class is the way to tell unittest module that this is a test case:

class PythonOrgSearch(unittest.TestCase):

The setUp is part of initialization, this method will get called before every test function which you are going to write in this test case class. Here you are creating the instance of Firefox WebDriver.

def setUp(self):
    self.driver = webdriver.Firefox()

This is the test case method. The test case method should always start with characters test. The first line inside this method create a local reference to the driver object created in setUp method.

def test_search_in_python_org(self):
    driver = self.driver

The driver.get method will navigate to a page given by the URL. WebDriver will wait until the page has fully loaded (that is, the “onload” event has fired) before returning control to your test or script. It’s worth noting that if your page uses a lot of AJAX on load then WebDriver may not know when it has completely loaded.:

driver.get("http://www.python.org")

The next line is an assertion to confirm that title has “Python” word in it:

self.assertIn("Python", driver.title)

WebDriver offers a number of ways to find elements using one of the find_element_by_* methods. For example, the input text element can be located by its name attribute using find_element_by_name method. Detailed explanation of finding elements is available in the Locating Elements chapter:

elem = driver.find_element_by_name("q")

Next we are sending keys, this is similar to entering keys using your keyboard. Special keys can be send using Keys class imported from selenium.webdriver.common.keys:

elem.send_keys("pycon")
elem.send_keys(Keys.RETURN)

After submission of the page, you should get result as per search if there is any. To ensure that some results are found, make an assertion:

assert "No results found." not in driver.page_source

The tearDown method will get called after every test method. This is a place to do all cleanup actions. In the current method, the browser window is closed. You can also call quit method instead of close. The quit will exit the entire browser, whereas close will close a tab, but if it is the only tab opened, by default most browser will exit entirely.:

def tearDown(self):
    self.driver.close()

Final lines are some boiler plate code to run the test suite:

if __name__ == "__main__":
    unittest.main()

2.5. Using Selenium with remote WebDriver

To use the remote WebDriver, you should have Selenium server running. To run the server, use this command:

java -jar selenium-server-standalone-2.x.x.jar

While running the Selenium server, you could see a message looking like this:

15:43:07.541 INFO - RemoteWebDriver instances should connect to: http://127.0.0.1:4444/wd/hub

The above line says that you can use this URL for connecting to remote WebDriver. Here are some examples:

from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities

driver = webdriver.Remote(
   command_executor='http://127.0.0.1:4444/wd/hub',
   desired_capabilities=DesiredCapabilities.CHROME)

driver = webdriver.Remote(
   command_executor='http://127.0.0.1:4444/wd/hub',
   desired_capabilities=DesiredCapabilities.OPERA)

driver = webdriver.Remote(
   command_executor='http://127.0.0.1:4444/wd/hub',
   desired_capabilities=DesiredCapabilities.HTMLUNITWITHJS)

The desired capabilities is a dictionary, so instead of using the default dictionaries, you can specify the values explicitly:

driver = webdriver.Remote(
   command_executor='http://127.0.0.1:4444/wd/hub',
   desired_capabilities={'browserName': 'htmlunit',
                         'version': '2',
                        'javascriptEnabled': True})