What is Selenium?
Selenium is the industry-standard open source testing framework. Developers can use Selenium to run fast and repeatable tests across all browsers and operating systems.
Selenium testing supports the most popular scripting languages, including Node.js, Java, Python, PHP, Ruby, or C#. Test scripts can be produced with the languages known best. Developers, QA, and even project managers can develop and review tests for all apps, speeding up the time to market.
Over the past twenty-plus years, Selenium has grown from a technology designed to drive a single browser and execute tests, to a standard protocol for programs to interact with a browser as if they were a human, an in-browser test record/playback tool (Selenium IDE), a distributed computing grid to run multiple tests at the same time (Selenium Grid), and more.
Selenium 4, the latest version of the Selenium test tool, natively allows developers and testers to write test scripts in different programming languages (Python, Java, Ruby, C#, NodeJS, etc.) that can run on different operating systems and browsers without modification.
Why Test With Selenium
Testing with Selenium is beneficial because it automates web applications across different browsers and platforms, ensuring consistent and reliable results. It is open-source, flexible, and supports multiple programming languages, making it a versatile choice for creating robust test suites. Here are some of the facts why you should test with Selenium:
Cross-Browser Testing: Selenium allows you to automate tests across browsers like Chrome, Firefox, Safari, and Edge, ensuring your web application works consistently for all users.
Cross-Platform: Selenium supports multiple operating systems, including Windows, macOS, and Linux, allowing you to test your application in various environments.
Cross-Language: Selenium supports Java, Python, C#, Ruby, and JavaScript, allowing you to write tests in the language you’re most comfortable with.
Open Source and Free: Selenium is open-source, which means it’s free to use. It has a large community that contributes to its development.
Integration Capabilities: It integrates with other tools like TestNG, JUnit, Maven, PyTest, NUnit, Mocha, and any CI tool, making it easier to create a complete testing pipeline.
Extensive Web Interaction: Selenium can interact with various web elements and handle complex scenarios, making it ideal for comprehensive testing.
How Does Selenium Work?
Selenium automates browser actions to simulate user interactions with a web application. It uses the WebDriver protocol to control the browser, allowing you to write scripts that perform actions like clicking buttons, entering text, and navigating through pages. Here’s a bit more detail on how it operates:
Script Creation: Write a test script in a programming language supported by the WebDriver protocol. This script includes commands to interact with the web page, like locating elements (buttons, text fields), performing actions (clicking, typing), and verifying outcomes.
WebDriver Commands: To control the browser, the test script sends WebDriver commands to the browser driver (like ChromeDriver for Chrome or GeckoDriver for Firefox). These commands can include opening a URL, clicking on elements, entering text, or extracting information from the page.
Browser Interaction: The browser driver translates these commands into actions the browser understands. Some of those actions could be to navigate to a URL or interact with web elements (such as a text field or a button) using various locators (such as ID, name, class, CSS selectors, or XPath). Afterwards, it can perform actions like clicking buttons, filling out forms, and navigating between pages, just as a user would.
Execution and Response: After executing each command, the browser driver sends a response back to the test script, which can include the browser's state or the action's results. This allows you to automate complex workflows and interact with the browser like a real user.
Understanding Selenium 4
Selenium 4 is the latest version of Selenium. Selenium 4 uses the W3C WebDriver standard protocol for browser automation. Because browser vendors only support W3C WebDriver, using Selenium 4 ensures the widest possible range of support across all browsers, essentially making automation scripts future-proof.
For more information on Selenium 4, see the following resources:
Selenium 3 vs Selenium 4
Developers and testers must keep up with the latest Selenium versions for effective automation testing. Selenium 3 was released in 2016 and emphasized stability and bug fixes, removing Selenium RC and keeping support for older versions. In 2021, Selenium 4 became the latest major update, bringing notable improvements to the framework, fixing previous limitations, and enhancing the testing experience. Here are some of the advantages of Selenium 4:
W3C WebDriver Protocol: Selenium 4 uses the W3C WebDriver protocol by default, whereas Selenium 3 mixed the JSON Wire Protocol and the W3C WebDriver protocol, which sometimes produced unexpected behaviors. This change improves communication between the WebDriver and browsers, reducing issues and enhancing stability.
Better Browser Support: Selenium 4 offers improved support for modern browsers, including new Chromium-based versions of Edge.
Enhanced DevTools Integration: Selenium 4 introduces integration with Chrome DevTools Protocol (CDP), enabling advanced browser interactions like capturing network requests, mocking geolocation, and accessing the browser console. This provides more powerful testing and debugging capabilities.
Bidirectional (BiDi) Protocol Support: CDP integration introduced several use cases that only work on Chromium-based browsers. Selenium 4 includes an initial implementation of the Bidirectional (BiDi) protocol, allowing for real-time communication between the browser and the client. This feature opens up capabilities like listening to console logs and network events, intercepting requests, and providing more control and insight during test execution across all browsers.
New Window and Tab Management: Selenium 4 simplifies handling multiple windows and tabs by introducing new methods like newWindow(), making it easier to open and switch between different browser windows or tabs.
Relative Locators: Selenium 4 introduces relative locators, allowing you to find elements based on their position relative to other elements, such as “to the left of” or “above” another element. This makes locating elements more flexible and intuitive.
Grid Architecture Overhaul: Selenium Grid in Selenium 4 has been revamped to support better observability, a more scalable architecture, and new features like Docker support, making it easier to run tests in parallel and in different environments.
Selenium WebDriver
Selenium WebDriver is a collection of open-source application programming interfaces (APIs) used to automate web applications. It allows users to execute their tests against a variety of different browsers, rather than just testing on Chrome or Firefox. Selenium WebDriver is language-agnostic and allows for automation testing in languages such as Ruby, Java, Python, C#, and JavaScript, among others.
WebDriver is an ideal tool for developers and testers who want to move from manual testing to automated testing.
Selenium IDE
Selenium IDE is an open-source record and playback test automation extension for Chrome, Firefox, and Edge browsers. It allows developers and testers to make simple recordings of their actions as they navigate a web application, and then turn the recordings into scripts. The scripts are recorded using a proprietary language but can be exported to WebDriver code using C#, Java, JavaScript, Ruby, or Python. Once a session has been recorded, users can rerun the session, manipulate session commands, and debug session runs.
Despite its simplicity, Selenium IDE may not suit larger environments. You should consider running WebDriver for these.
For more information on Selenium IDE, see our Selenium IDE Tutorial.
Selenium Grid
Selenium Grid enables developers, testers, and DevOps to run tests in parallel across multiple machines and to manage different browser versions and configurations. This helps to reduce the time spent running tests.
Selenium 4 introduced a brand new Grid, or Selenium Grid 4, which takes advantage of modern infrastructure features such as Docker and distributed tracing to bring observability into the Grid.
Benefits of Selenium Testing
By automating web app tests with Selenium, developers, and testers can test web apps across different operating systems and browser configurations to ensure every user has the same experience, regardless of what OS or browser version they’re using. Automated testing allows developers and testers to write test code that runs through all possible actions in a web app more quickly and effectively than manual testing alone.
Some benefits of automating web tests with Selenium include:
Automates browsers: Selenium automates browsers and, specifically, the human interactions with them, such as navigating to pages, clicking on elements, and typing text into input fields.
Works across browsers: Selenium works on every major browser, in every main software programming language, and with every major operating system.
Up to date: Each language binding and browser is actively being developed to stay current.
Runs anywhere: Selenium can run on a local computer, on a remote server, on a set of servers with Selenium Grid, or on a third-party cloud provider like Sauce Labs.
Enables parallel testing: Selenium allows developers to run multiple tests across multiple browsers and OS configurations at the same time. This helps to speed up testing and scale growing test suites.Allows customized testing: Selenium supports integration with other tools and frameworks, enabling you to tailor tests for different scenarios and environments.
Selenium for Automated Testing
Automated testing is a software testing technique that leverages automation technologies rather than human testers to control the execution of tests. The actual test findings are then compared to the expected outcomes. Your projects will be more efficient and have a shorter time to market if you use automated testing.
Automated testing is also referred to as test automation or automated QA testing. Well-implemented automated testing improves test coverage, increases execution speed, and reduces the manual effort involved in testing software.
Which tests can be automated with Selenium?
The following are some of the test cases that can be automated with Selenium:
Regression tests: Automated regression testing is ideal for sanity or smoke tests because they require significant human resources and are time-consuming.
Performance tests: Automated tests repetitively query the desired coverage to perform stress and load testing on the application, which is tedious and time-consuming when done manually.
Data-driven tests: Automation tests that use data allow you to run the same test with multiple data sets, enhancing test coverage and efficiency and minimizing human error.
Functional tests: Automation testing can also test whether frameworks and development codebases meet the desired specifications.
Integration tests: Automation testing helps identify integration faults and provides a reliable way of ensuring robustness between different modules and interfaces.
Cross-browser tests: Automated cross-browser testing helps verify if your website works as expected across various browsers, operating systems, devices, and resolutions.
See our test automation tutorial to learn more.
Getting Started with Selenium
Co-founded by the creator of Selenium, Sauce Labs provides a number of resources to learn more about getting started with test automation. Our documentation on Getting Started with Selenium provides a great overview of the basics of Selenium. Start your online browser tests with a free Sauce Labs trial today!
