Selenium is a free, open-source automation testing suite for web applications across different browsers and platforms. It is somewhat similar to HP QuickTest Pro (QTP, currently UFT). However, Selenium focuses on automating web-based applications. Testing done using the Selenium tool is usually referred to as Selenium testing. Remember, only testing web applications is possible with Selenium. You cannot use it to test desktop applications or mobile applications.
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As part of this tutorial, you will learn the following topics:
What is Selenium?
Selenium is a free automation testing suite of tools used for testing only web applications. There is no need to feel disappointed due to the fact that it only helps in testing web applications because various other software have got you covered. There are many tools available for testing desktop and mobile applications, such as IBM’s RFI, HP’s QPI, Appium, etc. However, the aim of this tutorial is to make you understand the testing of dynamic web applications and why Selenium is the best for it.
Since Selenium is an open-source tool, there is no licensing cost involved, which is a significant benefit over other testing tools. Other reasons behind Selenium’s ever-growing popularity are as follows:
- Test scripts are often written in any of these programming languages: Java, Python, C#, PHP, Ruby, Perl, and .Net.
- Tests can be carried out in any of these operating systems: Windows, Mac, or Linux.
- Tests can be carried out using any of these browsers: Mozilla Firefox, Internet Explorer, Google Chrome, Safari, or Opera.
- It can be integrated with tools such as TestNG and JUnit for managing test cases and generating reports.
- It is integrated with Maven, Jenkins, and Docker to achieve continuous testing.
Now, let’s learn briefly about the history of the Selenium tool.
Who developed Selenium?
History of Selenium
Soon, Simon Stewart from Google got tired of the limitations of the Selenium tool. He required a testing tool that was capable of communicating with the browser directly, and hence, he came up with WebDriver. A few years later, Selenium merged with WebDriver. This tool allowed professionals to do automation testing using a single tool, which was efficient.
Who uses Selenium?
Most programmers and developers who build website applications and wish to test them every now and then use Selenium. One of the biggest advantages of Selenium that has made it so popular is its flexibility. Any individual who creates web programs can use Selenium to test the code and applications. Further, professionals can debug and perform visual regression tests as per the requirements of the website or code.
In most organizations, it is the job of QA Engineers to test web apps using Selenium. They are required to write scripts that can help in maximizing accuracy and test coverage to make changes in the project and maintain the infrastructure of the test.
They are responsible for developing test suites that can identify bugs, using which they can inform stakeholders about the benchmarks set for the project. The main goal of the QA Engineers is to ensure efficiency and test coverage and increase productivity.
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Now, let’s talk about Selenium testing in particular and see where Selenium stands in the market.
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Selenium vs QTP
A comparison based on the performance factor of Selenium with another popular automation testing tool, QTP, is shown below.
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A Comparison Between Selenium and QTP (Now UFT)
QuickTest Professional (QTP) is a proprietary automation testing tool previously owned by the company, Mercury Interactive, before it was acquired by Hewlett Packard in 2006.
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Selenium Tool Suite has several benefits over QTP as elaborated below:
Advantages of Selenium over QTP
- Is open-source, i.e., it is free to use
- Is highly extensible
- Runs tests across different browsers
- Supports various operating systems
- Supports mobile devices
- Executes tests while the browser is minimized
- Executes tests in parallel
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- Is commercial
- Has limited add-ons
- Can only be used in Windows
- Supports mobile app test automation (iOS and Android) using the HP solution called HP Mobile Center
- Needs to have the application under test to be visible on the desktop
- Executes only in parallel but using HP Quality Center, which is again a paid product
It is pretty clear from the above comparison why Selenium is the most popular automation tool. However, there are several other nuances in Selenium testing, and you need to understand which one is the most applicable Selenium tool for your requirements.
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Further, let’s discuss manual testing and some of its disadvantages.
What is Manual Testing?
Manual testing is a form of software testing wherein all test cases are manually executed by testers without the help of any automation tool. This testing method helps in finding errors, bugs, and defects in web applications. It is a traditional testing method useful in identifying critical bugs in applications. All new applications need to be tested not just once but multiple times before being used, and that’s why, until automation testing, manual testing techniques were used to test the apps.
Let’s look at some of the difficulties and disadvantages faced by professionals while performing manual testing, which later led to the creation of automation testing tools like Selenium.
Challenges with Manual Testing
Professionals face numerous challenges with manual testing. Some of the major challenges faced by them are listed below:
- Testing the entire application: Whenever clients provide their requirements and the documentation to a tester, the tester is responsible for understanding all the requirements. In case of ambiguity, the tester must discuss the same with the respective client to get it cleared. It gets extremely difficult for them to understand each of the requirements, review it, and then build the respective test cases. Additionally, if the tester do not succeed in making the test cases accordingly, then it will be impossible to perform the tests properly.
- Complete test coverage: ‘100 percent testing’ is not a possible phrase in manual testing since there can always be an error. It is already difficult for engineers and developers to cover the entire application area while testing to find the maximum defects to improve the application. Hence, completing a test that covers 100 percent of the application is not possible.
- Regression test case coverage: After every release, applications expand and become so wide that professionals find it difficult to keep up with regression testing, continue the verification of new updates, perform tests in the old functions, keep a record of the existing defects, and track the new ones.
- Time constraint in test execution: It is difficult for testers to complete the entire application testing within the given deadline since the schedule is usually tight. The process of testing requires professionals not just to execute the testing process but also blog the defects, perform exploratory testing and regression testing, and more. While the management team may require the testers to focus on completing the task at hand rather than the quality of work and test coverage, it is necessary that the testers also focus on the quality of testing so that there are no errors and bugs.
- 100 percent automation: It is a preconceived notion that it is possible to achieve 100 percent automation, which is not true. No tester or programmer can automate all the test cases. It is a challenging job to automate all possible scenarios.
- Relationship with the developer: It is not easy to just identify the mistakes and errors and introduce them to developers so that they can fix them. Significantly, testers and developers must have a good relationship so that they can communicate with each other and easily fix the problems in the application. Testers should be extremely patient and have analyzing and troubleshooting skills so that they can justify the reasons why a particular defect needs to be fixed and what will be the effects on the application if it is not fixed properly.
- Thinking from the users’ perspective: One of the biggest challenges that testers face while testing any application is keeping in mind that numerous users with different backgrounds and requirements will use the application as per their needs. Therefore, these professionals must test the application in a way that most users can use it without any difficulty.
- Identifying difficult bugs: It is easy to find those bugs that are not as per the requirements of the client. However, the difficulty arises when the bugs are not in the document, and they need to be fixed as they are significant errors from the users’ point of view.
- Lack of skilled testers: Organizations at times hire testers who are not as skilled as they need to be for the projects they are assigned with. This can lead to utter chaos rather than making the task easy. In the end, the testing done might turn out to be insufficient, incomplete, etc., which will not satisfy the respective clients.
- Understanding project requirements: Testers should have all the knowledge and skills so that they can understand the requirements of the clients for a specific project. If by chance, testers fail to do so, they will not be able to test the web application correctly.
These are a few of the reasons why professionals use the Selenium automation testing tool instead of any manual testing methods and tools.
Selenium isn’t simply one tool but a collection of software, each catering to different testing needs of an organization. It has four components:
- Selenium Integrated Development Environment (IDE)
- Selenium Remote Control (RC)
- Selenium WebDriver
- Selenium Grid
Let’s now discuss each component in detail.
- What is Selenium IDE? IDE stands for Integrated Development Environment, which is a plug-in of the browser, Firefox. This is the simplest framework and, therefore, requires developers to switch to Selenium RC for advanced test cases.
- What is Selenium RC? RC stands for Remote Control, and it permits developers to code in the language of their preference. Selenium RC supports multiple programming languages, such as Java, C#, Python, etc.
- What is Selenium Grid? Selenium Grid is employed, along with Selenium RC, to execute parallel tests across multiple browsers.
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How to Choose the Right Selenium Tool for Your Needs
From project to project, testing requirements will be different, and Selenium, an open-source automation testing suite, has got you covered on this with its collection of different Selenium automation tools.
Selenium IDE (Integrated Development Environment) is the tool you use to develop your Selenium test cases. When you create your first IDE script, it may include the following concepts:
- Selenese commands, such as clickAndWait, assert, verify, type, open, etc.
- Locators such as ID, Name, XPath, CSS Selector, etc.
- Exporting test cases in various formats, such as .cs (C# source code), .java (Java source code), .py (Python source code), .rb (Ruby source code), etc.
- Creating tests with very little or no previous knowledge in programming
- Creating simple test cases and test suites that you can export later to Selenium RC or Selenium WebDriver
- Testing an online application only against Firefox and Chrome
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Selenium Remote Control or Selenium RC used to be the main testing framework for a long period in the Selenium project. It is the first tool for automated testing that enabled users to use any programming language of their choice. It offers the following features:
- Designing a test using a more expressive language than Selenese
- Running the test against different browsers (except HTMLUnit) on different operating systems
- Deploying the test across multiple environments using Selenium Grid
- Testing the web application with complex AJAX-based scenarios
- To use a particular programming language in designing the test suit
- To test applications that are rich in AJAX-based functionality
- To execute tests on the HTMLUnit browser
- To create customized test results
Selenium Grid is used with Selenium RC to run parallel tests across various machines and browsers simultaneously. Listed below are a set of things that professionals can do using Selenium Grid:
- Running Selenium RC scripts in multiple browsers and operating systems at the same time
- Running a large test suite that will complete within the soonest time possible
Selenium WebDriver Architecture
The architecture of Selenium WebDriver involves four major components as listed below:
- Selenium client libraries
- JSON Wire Protocol over HTTP client
- Browser drivers
Let’s learn a bit about these components now.
Selenium Client Libraries
Selenium makes it easy for professionals to execute browser automation with scripts in any programming language using Selenium client libraries. The libraries act as translators between Selenium and the respective test script. With the help of language bindings, these client libraries translate the test script, irrespective of the language it is written in, to Selenese. This allows Selenium to follow the given set of instructions easily.
(Selenese is a collection of commands in Selenium that helps in testing web apps.)
Most Selenium bindings aim to help in the following:
- C# Selenium testing
- PHP Selenium testing
- Java Selenium testing
- Python Selenium testing
- Ruby Selenium testing
JSON Wire Protocol over HTTP Client
Selenium enables testers to automate the process of browser testing. Using Selenium WebDriver, professionals can easily automate the browser by communicating with the most popular web browsers directly, including Opera, Safari, Google Chrome, etc. All the browsers have their browser drivers, and these drivers have their own HTTP servers.
The JSON Wire Protocol interacts with various browser drivers using their HTTP servers. It extracts information from the client libraries and provides the same to the respective driver.
All browsers have their own drivers that control all the actions that take place within that browser. Once the JSON Wire Protocol provides all the necessary information to the respective browser driver, this driver takes control over the browser so that testers can automatically execute Selenium test scripts. After this, the browser driver uses the HTTP server to send the respective feedback in the HTTP protocol.
Listed below are the browser drivers for some of the most popular browsers:
Selenium WebDriver allows testers to interact with numerous web browsers, including Mozilla Firefox, Microsoft Edge, Safari, and more. This automation tool helps in performing browser testing on the required web application.
What types of testing can be automated with Selenium?
Selenium can help in automating numerous types of testing. Let’s discuss them briefly.
This type of testing is done by developers in cases where a bug-fix or feature enhancement is made to a part of the website application. Unit testing can be challenging if the professionals need to work on numerous code changes in various application modules. There are various frameworks in unit testing that are designed for specific languages, such as NUnit for Python, JUnit for Java, etc., to automate the process of unit testing. The Selenium automation tool is easily compatible with all these frameworks, allowing developers to validate their unit testing across multiple combinations of operating systems and browsers.
Black Box Testing or System Testing
In the case of system testing or black box testing, testers are responsible for checking the system’s compliance based on particular requirements. They need to test the functionality of the application’s module from an end-to-end perspective. In this testing, the testers do not execute any tests prior, and they have no context of the given code. Besides, a QA Engineer of the organization needs to draft a script verifying all the functionalities of the respective system. Selenium allows testers to automate the scripts of black box testing, which helps in saving the bandwidth for professionals to brainstorm and think of more unique scenarios for testing.
Here, the members of the QA team perform a set of actions to ensure that all the units of the application work properly, both independently and when combined. They ensure that the modules produce the same results even after being integrated together. This is done when two or more modules of the application are put together to display one functionality. With the help of Selenium automation, testers can easily perform thorough integration testing after every release of the application. This helps in evaluating the functionality and behavior of various modules combined together to build the web application.
QA Engineers perform end-to-end testing of web applications from the perspective of an end-user. They are required to come up with a set of test cases to make sure that the web application functions smoothly at various points. The end-to-end testing process takes a large amount of time especially if the web application has numerous features and pages that need to be tested on multiple devices, browsers, and operating systems. Selenium automation makes this process easier as it allows professionals to run parallel testing to automate the browser. Further, Selenium automation also allows developers to create reports on performance parameters, test case statuses, etc.
Regression testing allows developers to gauge the end-to-end functionality of the given website application as and when there is any code pushed from one staging environment to another. This is to make sure that the new code does not hamper the present functionality of the web application. This is one of the significant reasons that professionals perform regression testing after every release cycle. Further, it also ensures that the current application works easily after the integration of the new features. Unfortunately, it is a monotonous process as professionals need to test the whole web application even if it is a minute change. Selenium WebDriver makes it possible to automate the continuous process of regression testing, saving a lot of time for the professionals.
Performance and Load Testing
End-users are interested in the performance of the web application and nothing more. Stakeholders set a target for the performance, and QA Engineers are responsible for running various tests to check if the application works as per the needs and expectations of the users. Rather than running the web app manually on numerous possible combinations of operating systems and browsers, professionals can use Selenium and automate the processes to calculate the performance matrix of the application.
In this tutorial, you learned about: What is Selenium testing? What is Selenium Tool Suite? What are the advantages of automation testing with Selenium over QTP? How to choose the right Selenium tool for your needs? And more.
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For a more detailed explanation of Selenium WebDriver, browser elements, locating browser elements present on a web application, and setting up Selenium with Maven and TestNG on Eclipse, check out this Selenium Tutorial!
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