A Brief Overview of Selenium As a Testing Tool

What Is Selenium?

Selenium is anopen-sourcetest automationframework thatallows test automation of web apps or websites across different browsers & operating systems. Selenium is compatible with many programming languages such as Java, JavaScript, Python, C#, etcwhich allow the testers to automate the website testing in any programming language. By using the Selenium framework, the testers will beable to deliver the test cycles fasterby automating the repeated test cases. WhenCI/CD pipelines are integrated thenSelenium can also help with a sturdy, bug-free release deployment pipeline.

Selenium WebDriver

Selenium WebDriverallows users to interact directly with browsers throughautomation testing scripts. There are many more programming languages such asJava, PHP, C#, Python, Ruby, Perl, and Javascript which are supported by the Selenium WebDriver. The browsers that are supported by the Selenium WebDriver includeMozilla Firefox, Google Chrome version 12.0.712.0 and above, Internet Explorer, Safari, Opera version 11.5 and above, and HtmlUnit version 2.9 and above, and the operating systems that are supported are Windows, Linux, Mac OS, and Solaris.

Selenium Grid

Selenium Gridis a beneficial component of the Selenium project. This allowsparallel testingacrossvarious browsers & OS combinations through a Client-Server model. The Server is known as the Hub which has multiple clients to interact with the Selenium Grid. With the Selenium Grid, the user can connect a server to multiple remote machines which can then be used to run a browser automation script over multiple browsers + OS configurations, simultaneously.

How Selenium Grid Works?

The Hub and Nodes are the two primary components that are used in the Selenium Grid.

Hub or Server: The client using the WebDrivergrants access requests through the Hub. In the Selenium grid, the Hub is responsible for sending commands to the Nodes through JSON Wire Protocol over HTTP.

Node or Client: In the Selenium grid, a Node is simply an instance of a Selenium WebDriver over a remote machine. Each node is an instance of a remote Selenium WebDriver responsible for interacting with the browsers based on the commands received from the Hub or the Server.

How do the Hub and Nodes work together in Selenium Grid?

Whenever any test script runs over the Selenium Grid, it is pushed to the Hub/Server where all the desired capabilities classes are assessed to figure out the test configurations.The desired capabilities classes arespecified bythe browser, the browser version, and the operating system over which the test script should be executed. Among all the registered nodes, the Hub finds a suitable Node that matches the desired capabilities. And then the Hub then sends commands to the Node for executing the script in the remote machine which meets with the right browser + OS configuration. The Selenium Grid profoundly minimizes the test runtime as it allows the user to run multiple test scripts over different remote devices, simultaneously.

Major Challenges of Selenium Grid

There are a few challenges with the Selenium Grid in-house infrastructure although this is an excellent option for browser testing.

Collection of Latest & Legacy Browsers: Automated web testing with the Selenium Grid can only be done with the browsers and the Operating system present in the user's remote machines. That means the user will have to ensure that always new nodes are updated and added to the Hub for thorough automated browser testing. This can be challenging since a lot of browser versions are released in a very short span of time.Collection of Devices & OS. The user has to keep track of the latest devices being launched by different vendors and have to spend a considerable amount of money to add new devices and operating system to the nodes.

Hardware Expenditure: The more nodes that are added to the Selenium Grid, the more expenditure would be required for processing the parallel testing. At least 4GB memory of RAM is required to process the Selenium Grid of two parallel runs. If the user wishes to run three tests in parallel then a 4GB memory RAM would rarely cut it.

Maintenance Takes A Toll: Some dedicated resources are required to manage the in-house Selenium grid infrastructure even after many new latest devices are added.

On-premise Restrictions: There are premises restrictions while using the Selenium Grid which means if the setup is present in the corporate office then the Selenium Grid cannot be accessed from anywhere else.

Selenium IDE

Selenium IDE offers an Integrated Development Environment to record and playback the test scripts which is also known as the Selenium Recorder and was first made available for use in 2006.Itis available as a Mozilla Firefox add-on and as a Google Chrome plugin.

The primary purpose of introducingtheSelenium IDE was to ease the process ofregression testingfor manual testers. With the introduction of Selenium IDE, all the user has to do is hit the record button and run the test manually in the browser and once the test case is executed, the user can stop the recording. The next time whenever the user needs to execute the test case, the user just needs to playback the recording, and the browser automation would take place. Whenever the Selenium IDE records the test cases, automatically a Selenese script is generated for every interaction that is made with the browser. Selenese is a scripting language that is exclusive to Selenium which offers various browser operations such as clicking a button, using the dropdown, etc.

Conclusion

Selenium is used for unit testing by the developers when any new feature enhancement or a bug fix is applied to the module of a web application. Unit testing can be very strenuous for the developers if they developer has to work over multiple code changes for many different modules. In that case, the test scripts can help to automate and check the bugs in the newly integrated features. QAs can draft scripts to verify the functionality of the entire system, they do not have any tests executed previously more the testers have any context of the code written by the developers but can help in testing the newly integrated feature.

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