Selenium Grid
Selenium Grid is a tool that distributes the tests across multiple physical or virtual machines so that we can execute script in parallel(simultaneously) that results in cutting down the time required for running tests. This dramatically accelerates testing across browsers and across platforms by giving us quick and accurate feedback.
Selenium Grid allows us to execute multiple instances of WebDriver or Selenium Remote Control tests in parallel which uses same code base, hence code need NOT be present on the system they execute. The selenium-server-standalone package includes Hub, WebDriver, and Selenium RC to execute the scripts in grid.
Selenium Grid has a Hub and a Node
Hub - The hub can also be understood as server which acts as the central point where the tests would be triggered. A Selenium Grid has ONLY one Hub and it is launched on a single machine once.
Node - Nodes are the Selenium instances that are attached to the Hub which will execute the tests. There can be one or more nodes in a grid which can be of any OS and can contain any of the Selenium supported Browsers.
Architecture
Architecture of Selenium Grid is explained with the help of simple flow diagram.
Working with Grid
In order to work with the Grid, we need to ensure that we follow certain protocol. Below are the major steps involved and let us lookg at each one of them in detail.
Configuring Hub
Configuring Nodes
Develop Script
XML Preperation
Test Execution
Result Analysis
CONFIGURING HUB
Step 1 : Download the latest Selenium Server standalone JAR file from http://docs.seleniumhq.org/download/. Download it by clicking on the version as shown below.
Step 2 : Start the Hub by Launching the Selenium Server using the following command. Now we will use the port '4444' to start the hub.
NOTE : Ensure that there are no other applications that are running on port# 4444.
java -jar selenium-server-standalone-2.25.0.jar -port 4444 -role hub -nodeTimeout 1000
Step 3 : Now open the browser and navigate to the URL http//localhost:4444 from Hub(The system where you have executed Step#2).
Step 4 : Now click on 'console' link and click 'view config'. The config of hub would be shown. As of now we haven't got any nodes, hence we will not be able to see the details.
CONFIGURING NODES
Step 1 : Logon to node(where you would like to execute the scripts) and place the 'selenium-server-standalone-2.42.2' in a folder. We need to point to the selenium-server-standalone JAR when launching the nodes.
Step 2 : Launch FireFox Node using the below command.
java -jar D:\JAR\selenium-server-standalone-2.42.2.jar -role node -hub http://10.30.217.157:4444/grid/register -browser browserName=firefox -port 5555
Where,
D:\JAR\selenium-server-standalone-2.42.2.jar = Location of the Selenium Server Standalone Jar File(on the Node Machine)
http://10.30.217.157:4444 = IP Address of the Hub and 4444 is the port of the Hub
browserName = firefox (Parameter to specify the Browser name on Nodes)
5555 = Port on which Firefox Node would be up and running.
Step 3 : After executing the command, Now come back to Hub. Navigate to the URL - http://10.30.217.157:4444 and the Hub would now display the the node attached to it.
Step 4 : Now let us Launch Internet Explorer Node. For Launching the IE Node, we need to ensure that we have Internet Explorer driver downloaded on the node machine.
Step 5 : To Download the Internet Explorer Driver, navigate to http://docs.seleniumhq.org/download/ and download based on the architecture of your OS. After you have downloaded, unzip the exe file and place it a folder which has to be referred while launching IE nodes.
Step 6 : Launch IE using the below command.
C:\>java -Dwebdriver.ie.driver=D:\IEDriverServer.exe -jar D:\JAR\selenium-server-standalone-2.42.2.jar -role webdriver -hub http://10.30.217.157:4444/grid/register -browser browserName=ie,platform=WINDOWS -port 5558
Where,
D:\IEDriverServer.exe = The location of the downloaded the IE Driver(on the Node Machine)
D:\JAR\selenium-server-standalone-2.42.2.jar = Location of the Selenium Server Standalone Jar File(on the Node Machine)
http://10.30.217.157:4444 = IP Address of the Hub and 4444 is the port of the Hub
browserName = ie (Parameter to specify the Browser name on Nodes)
5558 = Port on which IE Node would be up and running.
Step 7 : After executing the command, Now come back to Hub. Navigate to the URL - http://10.30.217.157:4444 and the Hub would now display the IE node attached to it.
Step 8 : Now let us Launch Chrome Node. For Launching the Chrome Node, we need to ensure that we have Chrome driver downloaded on the node machine.
Step 9 : To Download the Chrome Driver, navigate to http://docs.seleniumhq.org/download/ and navigate to Third Party Browser Drivers area and click on the version number '2.10' as shown below.
Step 10 : Download the Driver based on the type of OS. We will execute it on Windows Environment, hence we will download the Windows Chrome Driver. After you have downloaded, unzip the exe file and place it a folder which has to be referred while launching chrome nodes.
Step 11 : Launch chrome using the below command.
C:\>java -Dwebdriver.chrome.driver=D:\chromedriver.exe -jar D:\JAR\selenium-server-standalone-2.42.2.jar -role webdriver -hub http://10.30.217.157:4444/grid/register -browser browserName=chrome,platform=WINDOWS -port 5557
Where,
D:\chromedriver.exe = The location of the downloaded the chrome Driver(on the Node Machine)
D:\JAR\selenium-server-standalone-2.42.2.jar = Location of the Selenium Server Standalone Jar File(on the Node Machine)
http://10.30.217.157:4444 = IP Address of the Hub and 4444 is the port of the Hub
browserName = chrome (Parameter to specify the Browser name on Nodes)
5557 = Port on which chrome Node would be up and running.
Step 7 : After executing the command, Now come back to Hub. Navigate to the URL - http://10.30.217.157:4444 and the Hub would now display the chrome node attached to it.
DEVELOP SCRIPT
Step 1 : We will develop a test using TestNG. In the below example we will have launch each one of those browsers using remote webdriver can pass on their capabilities to the driver so that driver has all information to execute on Nodes.
The Browser Parameter would be passed from "XML" File.
package TestNG;
import org.openqa.selenium.remote.DesiredCapabilities;
import java.util.concurrent.TimeUnit;
import org.openqa.selenium.*;
import org.testng.annotations.AfterTest;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Parameters;
import org.testng.annotations.Test;
import java.net.URL;
import java.net.MalformedURLException;
import org.openqa.selenium.remote.RemoteWebDriver;
public class TestNGClass
{
public WebDriver driver;
public String URL, Node;
protected ThreadLocal<RemoteWebDriver> threadDriver = null;
@Parameters("browser")
@BeforeTest
public void launchapp(String browser) throws MalformedURLException
{
String URL = "http://www.calculator.net";
if (browser.equalsIgnoreCase("firefox"))
{
System.out.println(" Executing on FireFox");
String Node = "http://10.112.66.52:5555/wd/hub";
DesiredCapabilities cap = DesiredCapabilities.firefox();
cap.setBrowserName("firefox");
driver = new RemoteWebDriver(new URL(Node), cap);
//Puts a Implicit wait, Will wait for 10 seconds before throwing exception
driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
//Launch website
driver.navigate().to(URL);
driver.manage().window().maximize();
}
else if (browser.equalsIgnoreCase("chrome"))
{
System.out.println(" Executing on CHROME");
DesiredCapabilities cap = DesiredCapabilities.chrome();
cap.setBrowserName("chrome");
String Node = "http://10.112.66.52:5557/wd/hub";
driver = new RemoteWebDriver(new URL(Node), cap);
driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
//Launch website
driver.navigate().to(URL);
driver.manage().window().maximize();
}
else if (browser.equalsIgnoreCase("ie"))
{
System.out.println(" Executing on IE");
DesiredCapabilities cap = DesiredCapabilities.chrome();
cap.setBrowserName("ie");
String Node = "http://10.112.66.52:5558/wd/hub";
driver = new RemoteWebDriver(new URL(Node), cap);
driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
//Launch website
driver.navigate().to(URL);
driver.manage().window().maximize();
}
else
{
throw new IllegalArgumentException("The Browser Type is Undefined");
}
}
@Test
public void calculatepercent()
{
driver.findElement(By.xpath(".//*[@id='menu']/div[3]/a")).click(); // Click on Math Calculators
driver.findElement(By.xpath(".//*[@id='menu']/div[4]/div[3]/a")).click(); // Click on Percent Calculators
driver.findElement(By.id("cpar1")).sendKeys("10"); // Enter value 10 in the first number of the percent Calculator
driver.findElement(By.id("cpar2")).sendKeys("50"); // Enter value 50 in the second number of the percent Calculator
driver.findElement(By.xpath(".//*[@id='content']/table/tbody/tr/td[2]/input")).click(); // Click Calculate Button
String result = driver.findElement(By.xpath(".//*[@id='content']/p[2]/span/font/b")).getText(); // Get the Result Text based on its xpath
System.out.println(" The Result is " + result); //Print a Log In message to the screen
if(result.equals("5"))
{
System.out.println(" The Result is Pass");
}
else
{
System.out.println(" The Result is Fail");
}
}
@AfterTest
public void closeBrowser()
{
driver.quit();
}
}
Step 2 : The Browser parameter will be passed using an XML. Create an XML we need to create the same under project folder.
Step 3 : Select 'File' from 'General' and click 'Next'.
Step 4 : Enter the name of the file and click 'Finish'.
Step 5 : TestNg.XML is created under the project folder as shown below.
Step 6 : Contents of XML are shown below. We create 3 tests and put in a suite and mention parallel="tests" so that all tests would be executed parallelly.
xml version="1.0" encoding="UTF-8"?>
name="Suite" parallel="tests">
name="FirefoxTest">
name="browser" value="firefox" />
name="TestNG.TestNGClass" />
