Selenium Interview Questions

Selenium Testing is a type of automated testing framework that is used to validate web applications across different browsers and platforms. It supports various programming languages, such as Java, C#, Python, etc., and can be integrated with other tools, such as Maven, Jenkins, TestNG, etc. Selenium Testing consists of different components, such as Selenium IDE, Selenium WebDriver, Selenium Grid, etc. 

Some of the advantages of Selenium over other testing tools are:

It is open-source and free to use, which reduces the cost of testing.

It is cross-browser, cross-platform, and cross-language, which increases the coverage and compatibility of testing.

It is flexible and scalable, which allows the creation of complex and customized test scripts and scenarios.

It is compatible with various frameworks and tools, which enhances the functionality and performance of testing.

Selenium is composed of four main components, which are:

Selenium IDE: It is a browser add-on that allows the recording and playback of simple test scripts. It is mainly used for prototyping and exploratory testing.

Selenium WebDriver: It is a collection of language-specific bindings that enables the automation of web browsers. It is mainly used for creating robust and complex test scripts and suites.

Selenium Grid: It is a tool that allows the distribution and parallel execution of test scripts across multiple machines and environments. It is mainly used for achieving faster and continuous testing.

Selenium RC: It is a deprecated component that used to provide a server that can communicate with web browsers and execute test scripts. It is now replaced by Selenium WebDriver.

The latest versions are Selenium IDE 1.8.0, Selenium Server (formerly the Selenium RC Server) 2.22.0, Selenium Client Drivers Java 2.22.0, Selenium Client Drivers C# 2.22.0, Selenium Client Drivers Ruby 2.21.0, Selenium Client Drivers Python 2.22.1..

Locators are the ways of finding and interacting with the web elements in Selenium. There are different types of locators, such as:

By ID: It is the most reliable and fastest way of locating an element by its unique ID attribute.

By Name: It is the way of locating an element by its name attribute, which may not be unique.

By Class Name: It is the way of locating an element by its class attribute, which may be shared by multiple elements.

By Tag Name: It is the way of locating an element by its HTML tag name, such as <div>, <a>, etc.

By Link Text: It is the way of locating a link element by its visible text, which must be exact.

By Partial Link Text: It is the way of locating a link element by a part of its visible text, which can be partial.

By CSS Selector: It is the way of locating an element by using CSS rules and properties, such as id, class, attribute, etc.

By XPath: It is the way of locating an element by using XML path expressions, which can be absolute or relative.

Assert and verify commands are used to check the expected and actual results of a test step in Selenium. The differences between them are:

Assert command stops the execution of the test case if the condition fails, whereas verify command continues the execution of the test case even if the condition fails.

Assert command throws an exception and marks the test case as failed if the condition fails, whereas verify command logs the failure and marks the test case as passed if the condition fails.

Assert command is used for critical validations, whereas verify command is used for non-critical validations.

Selenium Grid is a tool that allows the distribution and parallel execution of test scripts across multiple machines and environments. Some of the advantages and disadvantages of using Selenium Grid are:

Advantages:

It reduces the time and resources required for testing by running multiple tests simultaneously.

It increases the coverage and compatibility of testing by running tests on different browsers, platforms, and versions.

It supports continuous integration and delivery by integrating with tools like Maven, Jenkins, etc.

Disadvantages:

It requires more configuration and maintenance efforts to set up and manage the grid infrastructure.

It may face network and performance issues due to the communication and synchronization between the nodes and the hub.

It may not support some advanced features and functionalities of the browsers, such as file upload, download, etc.

find Element and find Elements are methods in Selenium WebDriver that are used to locate the web elements using the locators. The differences between them are:

find Element method returns the first matching element in the web page, whereas findElements method returns a list of all matching elements in the web page.

find Element method throws a No Such Element Exception if no matching element is found, whereas findElements method returns an empty list if no matching element is found.

find Element method is used when we expect only one element to match the locator, whereas findElements method is used when we expect multiple elements to match the locator.

Waits are the methods in Selenium WebDriver that are used to handle the synchronization issues between the web browser and the web application. There are different types of waits, such as:

Implicit Wait: It is a global wait that tells the WebDriver to wait for a certain amount of time before throwing a No Such Element Exception if the element is not found. It is applied to all the elements in the test script by default and can be set only once.

Explicit Wait: It is a local wait that tells the WebDriver to wait for a certain condition to be met before proceeding with the execution. It is applied to specific elements in the test script and can be customized for different scenarios.

Fluent Wait: It is a type of explicit wait that tells the WebDriver to wait for a condition with a frequency and a maximum time limit. It also allows the WebDriver to ignore certain exceptions while waiting for the condition.

Thread.sleep: It is a Java method that tells the WebDriver to pause the execution for a fixed amount of time. It is not recommended to use as it may cause performance issues and may not work for dynamic web applications.

Pop-ups, alerts, and frames are the web elements that may appear on the web page and may require user interaction or navigation. Some of the methods and techniques to handle them in Selenium WebDriver are:

Pop-ups: Pop-ups are the windows that may open on the web page and may contain some information or advertisement. To handle pop-ups, we can use the following methods:

GetWindowHandles and switchTo methods: These methods are used to get the handles of all the open windows and switch to the desired window by using the handle.

Close and quit methods: These methods are used to close the current window or all the open windows respectively.

Alerts: Alerts are the dialog boxes that may appear on the web page and may display some message or require some input from the user. To handle alerts, we can use the following methods:

SwitchTo and alert methods: These methods are used to switch to the alert window and perform actions on the alert, such as accept, dismiss, getText, or sendKeys.

AutoIT or Robot class: These are the external tools or classes that are used to handle the alerts that are not generated by the browser, such as file upload or download alerts.

Frames: Frames are the web elements that may contain another web page within the web page. To handle frames, we can use the following methods:

SwitchTo and frame methods: These methods are used to switch to the frame window by using the index, name, or web element of the frame.

SwitchTo and defaultContent methods: These methods are used to switch back to the main window from the frame window.

Mouse and keyboard actions are the user interactions that are performed on the web elements using the mouse and keyboard devices. To perform mouse and keyboard actions in Selenium WebDriver, we can use the following classes and methods:

Actions class: It is a class that provides the methods to perform the complex user interactions, such as drag and drop, double click, right click, hover, etc. It uses the builder pattern to create a sequence of actions and perform them using the perform method.

Robot class: It is a Java class that provides the methods to perform the low-level user interactions, such as pressing and releasing keys, moving and clicking the mouse, etc. It uses the native system events to simulate the user actions.

Keys class: It is an enum class that provides the constants for the keyboard keys, such as ENTER, ESCAPE, TAB, etc. It can be used with the sendKeys method to send the keystrokes to the web elements or the browser.

Dynamic web elements are the web elements that change their attributes or values dynamically based on some actions or events, such as time, date, location, user input, etc. To handle the dynamic web elements in Selenium WebDriver, we can use the following strategies and techniques:

Using partial or relative locators: We can use partial or relative locators, such as partial link text, partial attribute value, relative XPath, etc., to locate the dynamic web elements that have some fixed or constant part in their attributes or values.

Using regular expressions: We can use regular expressions, which are the patterns or rules that match a set of strings, to locate the dynamic web elements that have some variable or random part in their attributes or values.

Using starts-with or ends-with functions: We can use starts-with or ends-with functions, which are the XPath functions that match the strings that start or end with a given substring, to locate the dynamic web elements that have some prefix or suffix in their attributes or values.

Using contains or text functions: We can use contains or text functions, which are the XPath functions that match the strings that contain a given substring or text, to locate the dynamic web elements that have some keyword or text in their attributes or values.

Using index or position functions: We can use index or position functions, which are the XPath functions that match the elements based on their order or position in the web page, to locate the dynamic web elements that have some sequence or pattern in their attributes or values.