Selenium Training Course

Selenium: Selenium is a range of tools & libraries that is aimed to support web browser automation. It is an open-source subproject. A playback tool is provided for authoring functional tests without the need to learn a test scripting language (Selenium IDE).

It also provides a test domain-specific language (Selenese) to write tests in several popular programming & coding languages such as Ruby, Java, NodeJS, PHP, Perl, C#, Python & Scala. Later on, the tests can run against most modern web browsers. It runs on macOS, Windows, Linux. Released under the Apache License 2.0, it is open-source software. It is one of the most widely used open-source Web UI (User Interface) automation testing suites. The components used are:

  Selenium IDE: It is a completely Integrated Development Environment (IDE) for Selenium tests. It is implemented as a Firefox Ad-on & as a Chrome Extension.

It allows recording, debugging & editing of functional tests. It was previously known as Selenium Recorder. It was previously little-maintained. In 2018, it began being actively maintained.

  Selenium client API: As an alternative for writing tests in Selenese tests can also be written in programming or coding languages. By calling methods in the Selenium Client API, later on, these tests communicate with Selenium. It currently provides client APIs for Python, Java, C#, Ruby, JavaScript, R, etc.    

Selenium Remote Control (RC): It is a server written in Java, that accepts commands for the browser via HTTP. RC makes it possible to write automated tests for a web application in any programming or coding language, which allows for better integration of Selenium in existing unit tests frameworks. To make writing tests easier, the Selenium project currently provides client drivers for PHP, Python, .NET, Perl, Java & Ruby.

JavaScript (via the Rhino engine) can also be used from the Java Driver. An instance of Selenium RC is needed to launch an Html test case – which means that the port should be different for each parallel run. However, only one Selenium RC instance needs to be running continuously, for Java/PHP test case.

  Selenium WebDriver: At the core of Selenium is Selenium WebDriver, an interface to write instructions that work interchangeably across browsers. It is the successor to Selenium RC. It accepts commands sent (sent in Selenese, or via a client API) & sends them to a browser.

This is implemented through a browser-specific browser driver, which sends commands to a browser & retrieves the results. Most browser drivers launch & access a browser application (such as Firefox, Google Chrome, Internet Explorer, Safari, or Microsoft Edge); there is also an HtmlUnit browser driver, which simulates a browser using the headless browser HtmlUnit.   

  Selenium Grid: It is a server that allows tests to use web browser instances running on remote machines.  One server act as the central hub. To obtain access to browser instances, tests contact the hub. The hub has a list of servers that provide access to browser instances (WebDriver nodes), & allows the tests to use these instances.

It allows running tests in parallel on multiple machines & to manage different browser versions & browser configurations centrally (instead of in each test).  The ability to run tests on remote browser instances is useful to spread a load of testing across several machines & to run tests in browsers running on different platforms or operating systems.