Parallel Testing with Selenium

In parallel testing, multiple tests can be run simultaneously in different execution modes, reducing execution time. This approach is particularly useful when running tests across multiple browsers or operating systems because it simplifies cross-browser testing. TestNG is often used with Selenium to provide seamless integration for execution.

Using parallel behavior in the TestNG.xml configuration file, TestNG can execute independent tests in parallel, simplifying the testing process and increasing efficiency.

Parallel Testing using Selenium and TestNG

Parallel execution is a very important concept in the field of automated testing. All the work we do at the same time always saves time. Similarly, in end-to-end testing of an application, running tests in parallel instead of sequentially saves us completion time; This will save us more time in the remaining stages of the software testing lifecycle and application delivery.

• Run parallel testing to improve our Selenium testing by running the most tests in the shortest amount of time.
• It helps large organizations run large-scale experiments. However, automation testers need to remember the following points before testing the same;
• for example, avoiding dependence of one test on another and adjusting parameters so that the test cannot be repeated successfully over several successful experiments.

Process of Parallel Testing

Parallel tests using TestNG and Selenium are a powerful way to run multiple tests simultaneously, thereby reducing overall execution time. Here are the steps to run parallel tests using TestNG and Selenium:

Step 1: Create a Maven Project

Create a Maven project in your IDE (e.g., IntelliJ IDEA, Eclipse) or use the following Maven command to create it via the terminal:

mvn archetype:generate -DgroupId=com.example -DartifactId=selenium-parallel-test -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

Step 2: Add Dependencies to pom.xml

Once the Maven project is created, open the pom.xml file and add dependencies for TestNG and Selenium WebDriver.

<dependencies>
    <!-- TestNG Dependency -->
    <dependency>
        <groupId>org.testng</groupId>
        <artifactId>testng</artifactId>
        <version>7.4.0</version>  <!-- Replace with the latest version -->
        <scope>test</scope>
    </dependency>

    <!-- Selenium WebDriver Dependency -->
    <dependency>
        <groupId>org.seleniumhq.selenium</groupId>
        <artifactId>selenium-java</artifactId>
        <version>4.0.0</version> <!-- Replace with the latest version -->
    </dependency>
    
    <!-- Selenium WebDriver for ChromeDriver -->
    <dependency>
        <groupId>org.seleniumhq.selenium</groupId>
        <artifactId>selenium-chrome-driver</artifactId>
        <version>4.0.0</version> <!-- Replace with the latest version -->
    </dependency>
    
    <!-- Selenium WebDriver for FirefoxDriver -->
    <dependency>
        <groupId>org.seleniumhq.selenium</groupId>
        <artifactId>selenium-firefox-driver</artifactId>
        <version>4.0.0</version> <!-- Replace with the latest version -->
    </dependency>
</dependencies>

Step 3: Create the Test Class

In this step, we create a TestNG test class called LoginTest.java to test login functionality on SauceDemo using Chrome and Firefox browsers in parallel.

package ParallelTesting;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.annotations.Test;

public class LoginTest {
    
    @Test
    public void testLoginInChrome() {
        WebDriver driver = new ChromeDriver();  // ChromeDriver setup
        driver.get("https://www.saucedemo.com");
        driver.findElement(By.id("user-name")).sendKeys("standard_user");
        driver.findElement(By.id("password")).sendKeys("secret_sauce");
        driver.findElement(By.id("login-button")).click();
        driver.quit();
    }

    @Test
    public void testLoginInFirefox() {
        WebDriver driver = new FirefoxDriver();  // FirefoxDriver setup
        driver.get("https://www.saucedemo.com");
        driver.findElement(By.id("user-name")).sendKeys("standard_user");
        driver.findElement(By.id("password")).sendKeys("secret_sauce");
        driver.findElement(By.id("login-button")).click();
        driver.quit();
    }
}

Step 4: Create the testng.xml File

This file defines how TestNG will execute the tests in parallel. In this case, we are running tests for both Chrome and Firefox in parallel.

<?xml version="1.0" encoding="UTF-8"?>
<suite name="Parallel Testing Suite" parallel="methods" thread-count="2">
    <test name="Chrome Test">
        <classes>
            <class name="ParallelTesting.LoginTest" />
        </classes>
    </test>
    <test name="Firefox Test">
        <classes>
            <class name="ParallelTesting.LoginTest" />
        </classes>
    </test>
</suite>

Step 5: Run the Tests

Eclipse: Right-click on the testng.xml file and Select Run As > TestNG Suite.

From Command Line using Maven: Open the terminal and navigate to your project directory and run the following Maven command:

mvn test

Step 6: View Results

Once the tests are executed, you can view the results in the Eclipse console or in the TestNG HTML report. You will find the report in the test-output folder within your project directory.

Difference between Parallelization vs Serialization

Parallelization aims to improve test performance by executing tests simultaneously, while serialization ensures that tests are executed one after another. The choice of this method depends on factors such as the needs of the test, available resources, and execution speed.

Serialization refers to the process of executing operations one by one in a thread of execution. In short, tasks are performed sequentially and each task starts only after the completion of the previous task.

Parallelization means executing a series of tasks on multiple threads, where one task is assigned to one thread. So these tasks are done together. This approach makes better use of multiple CPU cores and can improve application performance and performance.

Time Taken Report of Parallelization vs Serialization

Consider the case where we have code with two test methods. This process will run simultaneously in two different browsers: one test will run in Chrome and the other test will run in Firefox. This setup illustrates how parallelization enhances testing speed and provide a better return on investment (ROI).

In the example, we will do this step by step, one after the other. This approach contrasts with other examples where two methods work in parallel, creating two processes that can be done simultaneously. The image below shows the times required for the two methods, respectively:

1. Time Taken Report of Parallelization

2. Time Taken Report of Serialization

Both image indicates the time taken to execute the methods in parallel.

Advantages of Parallel Testing

Here are the Advantages of Parallel Testing:

1. Reduced Execution Time: Parallel testing reduces total test execution time by running multiple tests simultaneously, making it especially useful for large test runs or multi-type setups.
2. Allow Multi-Threaded Tests: TestNG's parallel execution enables simultaneous running of multiple threads on test cases, fostering independence in executing different software components.
3. Detect Issue: Parallel testing makes it easier to find the problem faster by providing rapid feedback on usage behavior in various situations, enabling timely solutions and reducing project time and associated costs.

Disadvantages of Parallel Testing

Here are the Disadvantages of Parallel Testing:

1. Dependent module failed: Parallel testing allows independent modules to be run simultaneously, but often results in failure when modules are interdependent. This problem often arises during experiments that must be completed or sacrificed for independence, both of which require more time and effort.
2. Debugging Complexity: Debugging parallel tests can be challenging due to concurrent execution, requiring more effort and time to pinpoint the root cause of failures or unexpected behavior.
3. Program flow information: To create a balanced testing model, testers need to have a deep understanding of the flow. Even the slightest interdependence can destroy the entire successful experiment. Testers need to know which modules must run simultaneously and which modules must follow a pattern to ensure proper operation.

Conclusion

We have probably mentioned all the scenarios that a software tester must handle during the testing phase of parallel testing. Integrated testing is possible when cross-browser testing is required. This requires installing Selenium Grid or accessing a cloud-based platform that provides you with Selenium Grid to run automated tests in parallel or in conjunction with different configurations.

Integrated testing not only saves testers' time, but also speeds up the delivery process following good results of verification and validation during testing. Try to improve your automated tests.