Exceptions in Selenium – All You Need To Know

In the world of software testing, exceptions play a crucial role in recognizing and managing unexpected occurrences during test automation. Selenium, a popular web automation tool, is not exempt from encountering exceptions. Building solid and dependable automated test scripts in Selenium requires an understanding of effectively handling exceptions. 

In programming, an exception refers to an event that disrupts the normal flow of execution. These exceptions need to be identified, understood, and appropriately handled to ensure the reliability and stability of automated tests. In this blog, we will talk about exceptions in Selenium and explore some of the most common ones that testers encounter, and best practices for handling them with some code examples as well. 

What are Exceptions in Selenium?

Exceptions in Selenium occur when something unexpected happens during the execution of test scripts in testing web browsers. These exceptions can range from elements not being discovered on a web page to timeouts exceeding the predefined limitations. Each exception offers useful details about the error, assisting testers in identifying and fixing problems. To get a better understanding of Selenium, you can pursue an online software testing course. 

Different Types of Exceptions in Selenium

Selenium has various types of Exceptions that occur while the execution of Selenium script, and disturb the flow of the process. Let’s explore them one by one: 

• StaleElementReferenceException – It is the Exception that occurs when a previously referenced element becomes stale or no longer valid. It is very common that when an element is refreshed or replaced by JavaScript the DOM is modified dynamically. 

• NullPointerException – Selenium NullPointerException (NPE) occurs when a Program attempts to perform an operation on a WebElement project that is not present or null. Which means that it does not point to any memory location. 

• NoSuchElementException – This exception occurs when Selenium cannot find the WebElement on a Web Page. It typically happens when the element is not present in the HTML code or when the element found by the locator is incorrect or wrong. 

• ElementNotVisibleException – This exception occurs when the Element is available on the Web Page but the user cannot find it. It usually happens when the element is hidden on the web page, overlapped by other elements, or located outside the visible area of the web page. 

• ElementNotInteractableException – It occurs when Selenium identifies the exception on the webpage, but cannot interact with it. It happens when the Element is read-only, disabled, or not in a condition to interact/accept any input from the user.

• TimeoutException – This exception occurs when Selenium waits for the Element or state for too long that it exceeds the particular period of time and timeout. It happens when waiting for an element to appear, disappear, or meet a specific condition, but the time limit is exceeded. 

• WebDriverException – This is a very usual problem that indicates an error in WebDriver or Browser Driver. It can happen due to issues like incorrect driver configuration, outdated driver version, or compatibility problems with the browser. 

• InvalidSelectorException – This exception occurs when an invalid selector is used to locate an Element. Generally, the Selector syntax or format is incorrect or unsupported. 

• NoSuchWindowException – This exception occurs very frequently. It occurs when the requisition is not found or updated. Sometimes the window title or handle does not match the available windows. 

• NoSuchFrameException – Likewise NoSuchWindowException, the exception occurs when the Frame cannot be found or switched to. This also occurs when the frame has a different name or index. 

• NoSuchCookieException – When a requested cookie cannot be accessed, found, or does not match the expected criteria then this exception occurs. 

• InvalidElementStateException – This exception occurs when the element is not in the condition to accept the requested operation such as typing in a disabled input field.

• ElementNotSelectableException – When an attempt is made to select an element that is not selectable then this exception occurs. The element is usually not in an option to select in a select drop-down. 

Handling Exceptions with Code Blocks

A crucial component of Selenium automation testing is exception handling. You can make sure that your test scripts continue to function normally and gracefully handle unexpected events by correctly handling exceptions. In this section, we will explore how to handle exceptions in Selenium using code blocks.

• Try-Catch Block: Try-catch blocks are one of the most popular methods for handling exceptions in any programming language. With Selenium, you can gracefully handle exceptions by wrapping code that can cause them in a try block and catching them in a catch block.

try
{
// Code that may throw an exception
} catch (Exception e) {
// Code for Handling exception
}

• Multiple Catch Block: In some circumstances, you may encounter multiple types of exceptions in Selenium. To handle each exception type differently, you can use multiple catch blocks.

try
{
//Code
} catch (ExceptionType1 e1) {
//Code for Handling Exception 1
} catch (ExceptionType2 e2) {
//Code for Handling Exception 2
}

• Finally Block: In addition to the try-and-catch blocks, you can also use a finally block to complete particular operations or execute cleanup tasks whether or not an exception was raised.

try {
//Code
} catch (ExceptionType1 e1) {
//Catch block
} catch (ExceptionType2 e2) {
//Catch block
} catch (ExceptionType3 e3) {
//Catch block
} finally {
//The finally block always executes.

• Throwing Exception: To give more detailed information about the problem, you might want to throw your own unique exceptions in particular circumstances. When debugging or handling particular cases in your test scripts, this can be helpful.

try {
// Type your code here.
} Catch (Exception b) {
// Perform whatever you want 
// Throw the Exception back to the system
throw(b);
}
}

Conclusion

Exception handling is a critical aspect of Selenium web testing. By understanding the different types of exceptions and implementing effective error-handling practices, testers can ensure the stability and reliability of their automated tests. With proper exception handling, testers can identify issues, provide informative error messages, and make their test scripts more robust. Embracing best practices for exception handling in Selenium contributes to efficient web testing and enhances the overall quality of web applications.