Monday, April 20, 2015

Distributed_Testing_with_Selenium_Grid

Distributed Testing with
Selenium Grid
In this chapter we will cover:
ff Setting up Selenium Grid Server for parallel execution
ff Adding Windows/IE node to Selenium Hub
ff Adding Mac/Firefox node to Selenium Hub
ff Adding iPhone/iWebDriver node to Selenium Hub
ff Adding Android node to Selenium Hub
ff Creating and executing Selenium script in parallel with TestNG
ff Creating and executing Selenium script in parallel with Python
ff Setting up Selenium with Jenkins CI for parallel execution
Introduction
Organizations are adopting virtualization and cloud-based technologies to reduce costs and
increase efficiency. Virtualization and cloud-based infrastructure can also be used to scale
the test automation by reducing investment in physical hardware needed to set up the test
environment. Using these technologies, web applications can be tested on a variety of browser
and operating system combinations. Selenium WebDriver has unmatched support for testing
applications in virtual environment, executing tests in parallel, reducing costs, and increasing
speed and coverage. This chapter will cover recipes to configure and execute Selenium
WebDriver tests for parallel or distributed execution.
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Running tests in parallel requires two things: an infrastructure to distribute the tests and a
framework that will run these tests in parallel in the given infrastructure. In this chapter, we
will first create a distributed infrastructure and then create some tests, which will be executed
in this distributed test environment.
Selenium Grid
Selenium Grid transparently distributes our tests across multiple physical or virtual machines
so that we can run them in parallel, cutting down the time required for running tests. This
dramatically speeds up testing, giving us quick and accurate feedback.
With Selenium Grid, we can leverage our existing computing infrastructure. It allows us
to easily run multiple tests in parallel, on multiple nodes or clients, in a heterogeneous
environment where we can have mixture of OS and Browser support. Here is an example of
the Selenium Grid architecture having capabilities to run tests on Linux, Windows, Mac, iOS,
and Android platforms:
Selenium
Test
Selenium
Test
Selenium
Test
Request to run:
Android
Request to run:
IE on Windows
Request to run:
Firefox on Linux
Selenium Grid Server
(Hub)
Linux &
Firefox
(Node)
Windows PC &
Internet Explorer
(Node)
Apple Mac OSX &
Chrome
(Node)
Apple iPad
IOS & Safari
(Node)
Android Phone
(None)
Web Application
- Keep Track of configurations
provided by nodes
-Ensure request are loadbalanced
between the nodes,
providing configuration
matching the request from
Selenium Test
Selenium Grid allows us to run multiple instances of WebDriver or Selenium Remote Control
in parallel. It makes all these nodes appear as a single instance, so tests do not have to
worry about the actual infrastructure. Selenium Grid cuts down on the time required to run
Selenium tests to a fraction of the time that a single instance of Selenium would take to run
and it is very easy to set up and use.
The selenium-server-standalone package includes the Hub, WebDriver, and Selenium RC
needed to run the grid.
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Testing the framework for parallel execution
In this chapter, we need a testing framework that supports parallel runs of our tests. We will
use TestNG (http://testng.org/) for running parallel tests with Selenium WebDriver Java
bindings. TestNG has a threading model to support running multiple instances of a same test
using an XML-based configuration. TestNG is pretty much similar to JUnit.
We will also use a raw method to run tests in parallel for Python bindings using the
subprocess module. However, you can also use nose for parallel execution in Python.
For running test in parallel with .NET bindings, you can use PUnit or MSTEST, and for Ruby, you
can use DeepTest.
Setting up Selenium Grid Server for parallel
execution
For running Selenium WebDriver tests in parallel, we need to set up the Selenium Grid
Server as a hub. This hub will provide the available configurations or capabilities to the
Selenium WebDriver tests. The slave machines, also called as node, connect to hub for
parallel execution. Selenium WebDriver tests use the JSON wire protocol to talk to the Hub
|for executing Selenium commands.
The Hub acts like the central point, which will receive the entire test request and distribute it
to the right nodes.
In this recipe, we will set up a Selenium Grid Server and then add nodes with different OS
and browser combinations, as shown in the following figure. We will then use this setup to run
tests in parallel using TestNG.
192.168.1.101 192.168.1.102 192.168.1.103 192.168.1.104
Windows PC &
Internet Explorer Node
Apple Mac OSX &
Chroma Node Apple iPad
iOS & Safari Node
Android Phone
(Node)
Web Application
Selenium Grid Server
(Hub)
Windows Server
192.168.1.100
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Getting ready
Download the latest Selenium Server standalone JAR file from http://code.google.
com/p/selenium/downloads/list. For this recipe, selenium-server-standalone-2.25.0
version is used.
How to do it...
Setting up a Hub is a fairly simple job. Launch the Selenium Server using the
following command:
java -jar selenium-server-standalone-2.25.0.jar -port 4444 -role hub
-nodeTimeout 600
This command will start the Selenium Server in Hub role with the following output on the
command prompt:
How it works...
When we launch the Selenium Standalone Server in Hub role, it starts listening to nodes and
Selenium tests on port 4444. If you browse to http://localhost:4444/grid/console
on the Hub machine, it will display the following information in the browser:
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After clicking on the view config link, it will display the configuration details of the Hub, as
shown in the following screenshot:
By default Hub provides 5 sessions on the server.
There's more...
For running tests with Selenium Grid, Selenium WebDriver tests need to use the instance
of the RemoteWebDriver and DesiredCapabilities classes to define which
browser, version, and platform tests will be executed on. Based on preferences set in the
DesiredCapabilities instance, the Hub will point the test to a node that matches these
preferences. In this example, Hub will point the test to a node running on the Windows
operating system and Firefox browser with the specified version:
DesiredCapabilities cap = new DesiredCapabilities();
cap.setBrowserName("firefox");
cap.setVersion("9.0.1");
cap.setPlatform(org.openqa.selenium.Platform.WINDOWS);
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These preferences are set using the setBrowserName(), setVersion(), and
setPlatform() methods of the DesiredCapabillities class.
An Instance of the DesiredCapabilities class is passed to RemoteWebDriver:
driver = new RemoteWebDriver(new
URL("http://192.168.1.100:4444/wd/hub"),cap);
In this example, the test is connecting to the Hub running on http://192.168.1.100:4444/
wd/hub with the instance of DesiredCapabilities named cap.
Adding Windows/IE node to Selenium Hub
For running tests in parallel, we will now add nodes to the Selenium Hub that we set up in
the previous recipe. It is recommended we test our web applications with major OS platforms
and browsers.
With Microsoft Windows being a widely used OS along with Internet Explorer, let us add a
node with Microsoft Windows and Internet Explorer capabilities to the Hub, so that tests can
provision this combination and test the application.
How to do it...
We can add a Windows/Internet Explorer node to the Hub in two ways. First, supplying all the
options as command line parameters described as follows:
1. To start and register a node to the Hub, use the following command by specifying
browser type, version, platform, hostname, and port as arguments:
java -jar selenium-server-standalone-2.25.0.jar -role webdriver
-browser "browserName=internet explorer,version=8,maxinstance=1,pl
atform=WINDOWS" -hubHost localhost –port 8989
2. Alternatively, a node can be added by creating a configuration file in JSON format and
then using the command:
{
"class": "org.openqa.grid.common.RegistrationRequest",
"capabilities": [
{
"seleniumProtocol": "WebDriver",
"browserName": "internet explorer",
"version": "8",
"maxInstances": 1,
"platform" : "WINDOWS"
}
],
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"configuration": {
"port": 8989,
"register": true,
"host": "192.168.1.100",
"proxy": "org.openqa.grid.selenium.proxy.
DefaultRemoteProxy",
"maxSession": 2,
"hubHost": "192.168.1.100",
"role": "webdriver",
"registerCycle": 5000,
"hub": "http://192.168.1.100:4444/grid/register",
"hubPort": 4444,
"remoteHost": "http://192.168.1.101:8989"
}
}
3. We can now pass the selenium-node-win-ie8.cfg.json configuration file through
command-line arguments shown as follows:
java -jar selenium-server-standalone-2.25.0.jar -role webdriver
-nodeConfig selenium-node-win-ie8.cfg.json
How it works...
An instance of Selenium Standalone Server is launched with WebDriver protocol on
the port specified in the configuration; in this example node, we will start running on
http://192.168.1.101:8989.
After a successful start, the node registers itself to the Hub. If you navigate to the Grid's
console on the hub, that is, http://localhost:4444/grid/console, you will see
Internet Explorer in the list of available nodes, as shown in the following screenshot:
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To register a node to the Hub, we need to supply browser details such as name of the browser,
version, OS platform, port of the node machine, and so on.
When the node is launched, it connects the Hub on port 4444 providing the capabilities
based on the configuration. For Internet Explorer, restrict the maxInstance property
to 1 only.
There's more...
In this example, we registered the node supporting the WebDriver protocol by using the
role parameter. We can also register this node to the Hub as a legacy Selenium RC node by
specifying the value node for the role parameter:
java -jar selenium-server-standalone-2.25.0.jar -role node -browser
"browserName=internet explorer,version=8,maxinstance=1,platform=WINDO
WS" -hubHost localhost –port 8989
Adding Mac/Firefox node to Selenium Hub
Similar to the Windows and IE mix, we will add a node combination by using Mac OS X and
Firefox and register this to the Hub.
The steps are pretty much similar to what we did in the previous recipe.
How to do it...
Similar to Windows and Internet Explorer, a node for Mac OS X and Firefox can be added
to the Hub in two ways. First, supplying all the options as command line parameters as
described in the following steps:
1. To start and register the node to the Hub, use the following command-line options:
java -jar selenium-server-standalone-2.25.0.jar -role webdriver
-browser "browserName=firefox,version=9.0.1,maxinstance=1,platform
=MAC" -hubHost localhost –port 8989
2. In another way a node can be added by creating a configuration file in JSON format
and then using the command:
{
"class": "org.openqa.grid.common.RegistrationRequest",
"capabilities": [
{
"seleniumProtocol": "WebDriver",
"browserName": "firefox",
"version": "9.0.1",
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"maxInstances": 1,
"platform" : "MAC"
}
],
"configuration": {
"port": 8989,
"register": true,
"host": "192.168.1.100",
"proxy": "org.openqa.grid.selenium.proxy.
DefaultRemoteProxy",
"maxSession": 2,
"hubHost": "192.168.1.100",
"role": "webdriver",
"registerCycle": 5000,
"hub": "http://192.168.1.100:4444/grid/register",
"hubPort": 4444,
"remoteHost": "http://192.168.1.102:8989"
}
}
3. We can now pass the selenium-node-mac-ff901.cfg.json configuration file
through the following command arguments:
java -jar selenium-server-standalone-2.25.0.jar -role webdriver
-nodeConfig selenium-node-mac-ff901.cfg.json
How it works...
After a successful start, the node registers itself to the Hub. Navigate to Grid's console on
the Hub. An entry for Firefox will appear in the list of available nodes along with the Internet
Explorer node added in the previous recipe:
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Adding iPhone/iWebDriver node to Selenium
Hub
We added nodes for desktop OS and browser combinations. There might be a need to test the
application on mobile platforms such as Apple iOS and Android. In this recipe, let's add a node
for the iOS Safari browser running on an Apple iPad device.
Let's start this by creating a node for the iOS platform (iPhone or iPad). We can simply add
an iOS device or simulator (iPhone or iPad) to the Selenium Grid server by installing the
iWebDriver application.
In this recipe, we will add an iPad to the Hub set up in the first recipe.
Getting ready
We need to install the iWebDriver application on the iOS device or simulator. See Chapter
7, Testing on Mobile Browsers, for the steps to install the iWebDriver application on an iOS
device or simulator.
How to do it...
Setting up an iOS device or a simulator on a Hub is much easier compared to setting up other
types of nodes:
1. Close the iWebDriver application if it's running.
2. Go to the iOS device or simulator Settings from the Home Screen.
3. Select iWebDriver. The settings for iWebDriver will be displayed on the screen.
4. In the Grid section, enter the Host and Port details of the Hub we already set in the
first recipe, as shown in the following screenshot:
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5. Start the iWebDriver application.
How it works...
Setting up an iOS device on the simulator on Hub does not require any configuration file or
command-line options. It can be set very easily from the settings UI in iOS.
When we enter the Host and Port details for Hub and start the iWebDriver application,
it automatically registers itself on the Hub providing the capability to run tests on the
iOS Safari browser.
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You can navigate to Hub console to check whether iOS device or simulator is added as a node.
In the following screenshot, iPad is added to the list of available nodes in the Grid console:
See also
ff The Setting up the iWebDriver App for the iPhone/iPad simulator recipe in Chapter 7,
Testing on Mobile Browsers
ff The Setting up the iWebDriver App for an iPhone/iPad device recipe in Chapter 7,
Testing on Mobile Browsers
Adding Android node to Selenium Hub
Now let's also add an Android device or AVD to the Hub for testing applications on the
Android browser.
For adding an Android node to the Hub, we need to install a utility written in Python, which will
help us to register the Android node to the Hub.
In this recipe, we will add an Android emulator to the Selenium Hub.
Getting ready
We need to install and set up WebDriver APK on an Android device or emulator. See
Chapter 7, Testing on Mobile Browsers, for the steps to install and set up WebDriver
APK on an Android device or emulator.
This recipe will also need Python installed on the machine.
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How to do it...
To register the Android node on the Hub, we need to install the flynnid (https://github.
com/davehunt/flynnid) utility in Python.
1. Use the following command to install flynnid in Python:
pip install flynnid
2. Now, let's register the Android node by calling flynnid from the command prompt with
the following options:
flynnid --nodeport=8080 --browsername=android --browserver=2.20
--platform=ANDROID
How it works...
The flynnid utility registers the Android node by using configurations provided as command
arguments. We need to supply the port of the Android node, browser name, platform Android
and version of the Android Server APK installed on the Android device or emulator.
Once the node is registered successfully on the Hub, the Android node will be listed on the
Grid console with a tiny Android icon, shown as follows:
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See also
ff The Setting up the Android emulator for Selenium recipe in Chapter 7, Testing on
Mobile Browsers
ff The Setting up the Android device for Selenium recipe in Chapter 7, Testing on
Mobile Browsers
Creating and executing Selenium script in
parallel with TestNG
Now that we have our Selenium Grid Hub and nodes ready and configured from previous
recipes, it's time to run tests in parallel with this distributed environment.
For running tests in parallel, we need a test framework that supports distributing tests on
these nodes. We will use TestNG for running tests in parallel for Selenium tests developed
with Java bindings.
TestNG (http://testng.org) is another popular Unit testing framework used by the Java
community after JUnit. TestNG allows us to create tests that can be executed in parallel. We
can set up a group of tests or test suites and have parameters configured to run these tests in
parallel. It uses a multithreading model to run tests in parallel.
TestNG requires that we have an XML configuration file with details of configurations that are
needed to run the tests in parallel. Before starting the run, TestNG reads this configuration file
to setup the test.
In this recipe, we use TestNG to create tests that are parameterized for parallel runs. This
recipe is divided in two parts; in the first part we will create a configuration file based on the
Hub and the nodes that we have configured so far and then in the second part we will be
creating a test case using TestNG annotations and parameterization features.
Getting ready
Make sure you have TestNG installed on the machine from where the tests will be launched.
You can download TestNG from http://testng.org/doc/index.html.
How to do it...
Let's create and execute a test in parallel with the following steps:
1. Before we create a test for parallel execution, first we need to create a configuration
file, which TestNG will need to run the tests in parallel. We will provide four
parameters for tests, platform, browser, version, and URL.
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Create a new conf.xml file in your projects source directory and add the following
code to this file:
<!DOCTYPE suite SYSTEM http://testng.org/testng-1.0.dtd>
<suite name="Parallel Tests" verbose="1" thread-count="4"
parallel="tests">
</suite>
2. Add the <test> node for a test that will be executed on the Windows and Internet
Explorer combination in the conf.xml file as follows:
<tests>
<test name="Windows+IE9 Test">
<parameters>
<parameter name="platform" value="Windows" />
<parameter name="browser" value="Internet
Explorer" />
<parameter name="version" value="8" />
<parameter name="url" value="http://
dl.dropbox.com/u/55228056/bmicalculator.html"/>
</parameters>
<classes>
<class name="SeGridTest" />
</classes>
</test>
</tests>
3. Add the following combinations to conf.xml. It should have the following entries:
<suite name="Parallel Tests" verbose="1" thread-count="4"
parallel="tests">
<tests>
<test name="Windows+IE9 Test">
<parameters>
<parameter name="platform"
value="Windows" />
<parameter name="browser"
value="Internet Explorer" />
<parameter name="version" value="8" />
<parameter name="url" value="http://
dl.dropbox.com/u/55228056/
bmicalculator.html"/>
</parameters>
<classes>
<class name="SeGridTest" />
</classes>
</test>
<test name="Mac+Firefox Test">
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<parameters>
<parameter name="platform"
value="Mac" />
<parameter name="browser"
value="Firefox" />
<parameter name="version"
value="9.0.1" />
<parameter name="url" value="http://
dl.dropbox.com/u/55228056/
bmicalculator.html"/>
</parameters>
<classes>
<class name="SeGridTest" />
</classes>
</test>
<test name="iOS Test">
<parameters>
<parameter name="platform"
value="MAC" />
<parameter name="browser"
value="iPad" />
<parameter name="version" value="" />
<parameter name="url" value="http://
dl.dropbox.com/u/55228056/
mobilebmicalculator.html"/>
</parameters>
<classes>
<class name="SeGridTest" />
</classes>
</test>
<test name="Andorid Test">
<parameters>
<parameter name="platform"
value="Android" />
<parameter name="browser"
value="Android" />
<parameter name="version" value="2.6" />
<parameter name="url" value="http://
dl.dropbox.com/u/55228056/
mobilebmicalculator.html"/>
</parameters>
<classes>
<class name="SeGridTest" />
</classes>
</test>
</tests>
</suite>
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4. Now we need to create a test using TestNG. We will create a parameterized test
using TestNG's parameterization features. We will create a test for the BMI calculator
application. We will use both the normal web and mobile web version of this application.
Create a new test with the name as SeGridTest and copy the following code:
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.By;
import org.openqa.selenium.remote.DesiredCapabilities;
import org.openqa.selenium.remote.RemoteWebDriver;
import static org.testng.Assert.*;
import org.testng.annotations.AfterTest;
import org.testng.annotations.Parameters;
import org.testng.annotations.Test;
import org.testng.annotations.BeforeTest;
import java.net.MalformedURLException;
import java.net.URL;
public class SeGridTest {
WebDriver driver = null;
private StringBuffer verificationErrors = new StringBuffer();
@Parameters({ "platform","browser","version", "url" })
@BeforeTest(alwaysRun=true)
public void setup(String platform, String browser, String
version, String url) throws MalformedURLException
{
DesiredCapabilities caps = new DesiredCapabilities();
//Platforms
if(platform.equalsIgnoreCase("Windows"))
caps.setPlatform(org.openqa.selenium.Platform.
WINDOWS);
if(platform.equalsIgnoreCase("MAC"))
caps.setPlatform(org.openqa.selenium.Platform.MAC);
if(platform.equalsIgnoreCase("Andorid"))
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caps.setPlatform(org.openqa.selenium.
Platform.ANDROID);
//Browsers
if(browser.equalsIgnoreCase("Internet Explorer"))
caps = DesiredCapabilities.internetExplorer();
if(browser.equalsIgnoreCase("Firefox"))
caps = DesiredCapabilities.firefox();
if(browser.equalsIgnoreCase("iPad"))
caps = DesiredCapabilities.ipad();
if(browser.equalsIgnoreCase("Android"))
caps = DesiredCapabilities.android();
//Version
caps.setVersion(version);
driver = new RemoteWebDriver(new URL("http://
localhost:4444/wd/hub"), caps);
// Open the BMI Calculator Application
driver.get(url);
}
@Test(description="Test Bmi Calculator")
public void testBmiCalculator() throws InterruptedException {
WebElement height = driver.findElement(By.
name("heightCMS"));
height.sendKeys("181");
WebElement weight = driver.findElement(By.
name("weightKg"));
weight.sendKeys("80");
WebElement calculateButton = driver.findElement(By.
id("Calculate"));
calculateButton.click();
try {
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WebElement bmi = driver.findElement(By.
name("bmi"));
assertEquals(bmi.getAttribute("value"),"24.4");
WebElement bmi_category =
driver.findElement(By.name("bmi_category"));
assertEquals(bmi_category.getAttribute
("value"),"Normal");
} catch (Error e) {
//Capture and append Exceptions/Errors
verificationErrors.append(e.toString());
}
}
@AfterTest
public void afterTest() {
//Close the browser
driver.quit();
String verificationErrorString =
verificationErrors.toString();
if (!"".equals(verificationErrorString)) {
fail(verificationErrorString);
}
}
}
How it works...
First, we created a test configuration file listing the combination of tests that we want to run in
parallel. Each instance of a test is listed in the <test> tag:
<test name="Windows+IE9 Test">
<parameters>
<parameter name="platform" value="Windows" />
<parameter name="browser" value="Internet Explorer" />
<parameter name="version" value="8" />
<parameter name="url" value="http://dl.dropbox.
com/u/55228056/bmicalculator.html"/>
</parameters>
<classes>
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<class name="SeGridTest" />
</classes>
</test>
In the <parameters> section we provided platform, browser, and browser version. Last
we added URL as we want to run this test both for normal and mobile web versions of the
application. Next, we need to specify the name of the test class in the <class> node. If you
are storing the test class in a package, then specify the complete path. For example, if we
keep SeGridTest in the package com.bmicalcapp.test then the following will be the
value that we will pass:
<classes>
<class name="com.bmicalcapp.test.SeGridTest" />
</classes>
Next, we created a parameterized test in TestNG. We added a setup() method, which
accepts arguments to set the options for the DesiredCapabilities class for running tests
for each combination specified in the configuration file:
@Parameters({ "platform","browser","version", "url" })
@BeforeTest(alwaysRun=true)
public void setup(String platform, String browser, String version,
String url) throws MalformedURLException
{
DesiredCapabilities caps = new DesiredCapabilities();
//Platforms
if(platform.equalsIgnoreCase("Windows"))
caps.setPlatform(org.openqa.selenium.Platform.WINDOWS);
if(platform.equalsIgnoreCase("MAC"))
caps.setPlatform(org.openqa.selenium.Platform.MAC);
if(platform.equalsIgnoreCase("Andorid"))
caps.setPlatform(org.openqa.selenium.Platform.
ANDROID);
//Browsers
if(browser.equalsIgnoreCase("Internet Explorer"))
caps = DesiredCapabilities.internetExplorer();
if(browser.equalsIgnoreCase("Firefox"))
caps = DesiredCapabilities.firefox();
if(browser.equalsIgnoreCase("iPad"))
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caps = DesiredCapabilities.ipad();
if(browser.equalsIgnoreCase("Android"))
caps = DesiredCapabilities.android();
//Version
caps.setVersion(version);
driver = new RemoteWebDriver(new URL("http://localhost:4444/wd/
hub"), caps);
// Open the BMI Calculator Application
driver.get(url);
}
When we execute the tests, we need to tell TestNG to use the conf.xml file for test
configurations. TestNG will read this file and create a pool of threads (for this example, it will
create four threads) for each combination calling the test class. It will then create and assign
an instance of test class to each thread by passing the parameters from the configuration
file to the setup() method. TestNG will run the test concurrently for each combination,
monitoring and reporting the test status and final results. The following is a report it generates
after running the test for combinations specified in the configuration file:
See also
ff The Creating a data-driven test using TestNG recipe in Chapter 4, Data-driven Testing
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Creating and executing Selenium script in
parallel with Python
As we have seen in the previous recipe, TestNG provides a very powerful execution framework
for running tests in parallel for Java bindings.
However, if you are using Python or another binding to develop Selenium WebDriver tests, you
can also run tests in parallel for distributed testing.
In this recipe, we will create and execute tests in parallel with Python bindings using the
subprocess module. We will use the Hub and nodes configured in earlier recipes to run
these tests.
How to do it...
We will create two test scripts for testing the application with Firefox and Internet Explorer
using the following steps. You can also create a single test and parameterize it similar to what
we did for TestNG:
1. For the first Python test, which will test the application functionality using the Firefox
browser, name this test as testOnFirefox.py and copy the following code:
from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import
DesiredCapabilities
from selenium.webdriver.support.ui import WebDriverWait
import time, unittest
class OnFirefox (unittest.TestCase):
def setUp(self) :
self.driver = webdriver.Remote(
command_executor='http://localhost:4444/wd/hub',
desired_capabilities=DesiredCapabilities.Firefox)
def test_Google_Search_FF(self):
driver = self.driver
driver.get("http://www.google.com")
inputElement = driver.find_element_by_name("q")
inputElement.send_keys("Cheese!")
inputElement.submit()
WebDriverWait(driver, 20).until(lambda driver :
driver.title.lower().startswith("cheese!"))
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self.assertEqual("cheese! - Google Search",driver.
title)
def tearDown(self):
self.driver.quit()
if __name__ == "__main__":
unittest.main()
2. For the second Python test, which will test the application functionality using the
Internet Explorer browser, name this test as testOnIE.py and copy the following code:
from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import
DesiredCapabilities
from selenium.webdriver.support.ui import WebDriverWait
import time, unittest
class OnInternetExplorer (unittest.TestCase):
def setUp(self) :
self.driver = webdriver.Remote(
command_executor='http://localhost:4444/wd/hub',
desired_capabilities=DesiredCapabilities.
INTERNETEXPLORER)
def test_Google_Search_IE(self):
driver = self.driver
driver.get("http://www.google.com")
inputElement = driver.find_element_by_name("q")
inputElement.send_keys("Cheese!")
inputElement.submit()
WebDriverWait(driver, 20).until(lambda driver :
driver.title.lower().startswith("cheese!"))
self.assertEqual("cheese! - Google Search",driver.
title)
def tearDown(self):
self.driver.quit()
if __name__ == "__main__":
unittest.main()
Distributed Testing with Selenium Grid
24
3. Finally, we need to create a Python script, which will use the subprocess module to
run these tests concurrently on different nodes. Name this script as runner.py:
from subprocess import Popen
import glob
tests = glob.glob('test*.py')
processes = []
for test in tests:
processes.append(Popen('python %s' % test, shell=True))
for process in processes:
process.wait()
How it works...
We need to place all three scripts in the same directory. When we execute runner.py, it
collects all the tests with names starting as test using the glob function. Then we create
a hash for processes and append each test using the Popen function from the subprocess
module. The Popen() function calls each test using Python as a subprocess of the main
process and waits for the script to complete.
There's more...
We can also use nose module for Python to run the tests in parallel. We need to install nose
by using the following command:
easy_install nose==0.11 multiprocessing
After nose is installed, you need to open the folder where all the tests are stored and use the
following command:
nosetests --processes=2
This will call the nosetests scripts, which will locate all the files with test prefix in the current
directory and start running tests concurrently. In this example, we are running two tests so
we need to specify the value for processes argumented as 2. nose module internally uses
multiprocessing module for concurrent execution.
See also
ff The Creating and executing Selenium script in parallel with TestNG recipe
Distributed Testing with Selenium Grid
25
Setting up Selenium with Jenkins CI for
parallel execution
As continuous integration is a widely accepted practice, it is essential that we run Selenium
WebDriver tests as part of the CI process for early feedback and increased confidence.
Jenkins is widely used as a continuous integration server tool in Java world.
Instead of having a plain Selenium Grid, Jenkins provides a Selenium Grid that can be very
well integrated with the CI infrastructure. We can use Jenkins' powerful distributed model
for CI to run our Selenium tests in parallel on a Jenkins cluster. In this recipe, we will set up
Jenkins for Selenium Grid.
Getting ready
Download and install Jenkins from https://jenkins-ci.org/.
How to do it...
We need to install Jenkins Selenium Plugin to add Selenium Grid support in Jenkins. Use the
following steps to install and configure Jenkins Selenium Plugin:
1. Click Manage Jenkins on the Jenkins Dashboard.
2. Click on Manager Plugins from the Manage Jenkins option.
3. Click on the Available tab.
4. Locate and select Jenkins Selenium Plugin from the list of available plugins.
5. Click on the Download now and install after restart button.
6. A new screen will be displayed Installing Plugins/Upgrades.
7. After the plugin is downloaded, restart Jenkins. Make sure that no jobs are running
while you restart.
8. After Jenkins restarts, a Selenium Grid link will appear on the left side
navigation pane.
9. Click on Selenium Grid, the Registered Remote Controls page will be displayed.
10. Selenium Grid is now available on http://localhost:4444/wd/hub for tests.
How it works...
On Jenkins master, Selenium Grid Hub is started on port 4444. This is where all Selenium
WebDriver tests should connect, same as using a normal Selenium Grid.
Distributed Testing with Selenium Grid
26
When we set up a Jenkins slave, necessary binaries are copied and Selenium RCs are started
automatically by Jenkins. Selenium running on slaves and the Selenium Grid Hub on master
are hooked up together automatically.
Along with the standard platform matching capability offered out of the box by Selenium
Grid, Jenkins allows us to specify jenkins.label as a capability, whose value is a Boolean
expression of labels/slave names to narrow down where to run the tests:
DesiredCapabilities cap = DesiredCapabilities.firefox();
cap.setCapability("jenkins.label","redhat5 && amd64");
WebDriver driver = new RemoteWebDriver(new
URL("http://192.168.1.100:4444/wd/hub"), cap);
In the previous example, Jenkins Selenium Grid will point the tests to the Jenkins slave with
redhat5 and amd64 as a label set in Jenkins cluster.
This capability is automatically added to grid nodes that are launched by Jenkins.
Jenkins Selenium Grid can also accept additional nodes running on a Selenium Standalone

Server launched outside of Jenkins.

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