Exceptions in Selenium | How to Handle Them?

Selenium WebDriver, a key tool for web application testing, often encounters exceptions due to network stability, slow page loads, and syntax errors. Understanding and managing these exceptions, which range from insufficient wait times to incorrect parameters, is crucial for effective testing. This article delves into common Selenium exceptions and strategies for handling them efficiently.

What is an Exception?

A programming error is an exception. It takes place when the program is running. When a program comes across an exception, it halts operation and issues a warning. When the code cannot find a web element or there is a problem with the web page's loading speed, Selenium WebDriver may throw an exception. It's critical to comprehend the different exceptions in Selenium WebDriver and how to manage them properly. For example, org.openqa.selenium.NoSuchElementException This exception is thrown when the driver is unable to locate an element.`

Advantages and Disadvantages of the Avoid-Handle Approach

Selenium WebDriver employs the avoid-handle strategy as a method for handling potential exceptions that can arise while running tests. The method consists of two key strategies: dealing with Selenium exceptions when they do arise and preventing them whenever possible.

Using strategies like explicit waits and well-designed locators to confirm that the items are accessible before attempting to interact with them are two ways to avoid Selenium exceptions. Since the WebDriver waits for the element to be ready before attempting to interact with it, this can lessen the likelihood of exceptions occurring.

Here are the advantages and disadvantages of the avoid-handle approach:

Advantages:

• Improved test stability: By both avoiding exceptions whenever possible and handling them when they do occur, the tests are more likely to be stable and reliable.
• Faster test execution: By avoiding Selenium exceptions and handling them efficiently, tests can be executed more quickly.
• Cleaner test code: By using a combination of techniques to avoid and handle exceptions, the resulting test code can be cleaner and easier to read.
• Increased flexibility: The avoid-handle approach provides a more flexible approach to handling exceptions in Selenium, allowing tests to continue executing even if unexpected situations occur.
• Improved test coverage: By avoiding exceptions when possible and handling them efficiently when they do occur, tests can exercise more functionality of the application, resulting in better test coverage.

Disadvantages:

• Increased complexity: The avoid-handle approach can sometimes involve writing more complex code that checks for certain conditions or waits for elements to become available.
• Reduced test stability: While the avoid-handle approach can improve test stability, there is still the potential for unexpected failures.
• Complex code: Handling exceptions in Selenium can sometimes result in more complex test code, which can be harder to read and maintain.

Types of Exceptions in Java and Selenium

In Java and Selenium, several types of exceptions can occur during test execution. Here are some of the most common ones:

• Checked exceptions:

  • Checked exceptions are exceptions that must be declared in a method or constructor's throws clause.
  • Examples include IOException, FileNotFoundException, and ClassNotFoundException.

• Unchecked exceptions:

  • Unchecked exceptions are exceptions that don't need to be declared in a method or constructor's throws clause.
  • They are typically caused by programming errors or unexpected runtime conditions.
  • Examples include NullPointerException, ArithmeticException, and IndexOutOfBoundsException.

• RuntimeException:

  • RuntimeException is a subclass of unchecked exceptions that indicates a programming error or unexpected runtime condition.
  • Examples include IllegalStateException and UnsupportedOperationException.

• WebDriver exceptions:

  • WebDriver exceptions are exceptions that are specific to Selenium WebDriver.
  • They are typically caused by problems with interacting with the web page or browser.
  • Examples include NoSuchElementException, NoSuchWindowException, and TimeoutException.

• Assertion errors:

  • Assertion errors are errors that occur when an assertion fails during test execution.
  • They are typically used to verify that certain conditions are met during the test.
  • Examples include AssertionError and AssertionFailedError.

Exception Handling

Exception handling in Selenium WebDriver is critical to the success of your test automation efforts. There are three basic steps to handling exceptions in Selenium WebDriver:

Step 1: Identify the Exception

• The first step in handling exceptions in Selenium WebDriver is to identify the exception that has been thrown.
• You can do this by checking the error message in the console or log file. Once you have identified the exception, you can move on to step 2.

Step 2: Handle the Exception

The second step in handling exceptions is to handle the exception. There are several ways to handle exceptions in Selenium WebDriver, including:

• Using try-catch blocks

  • One of the most common ways to handle exceptions in Selenium WebDriver is by using try-catch blocks.
  • This allows you to catch the exception and handle it gracefully. Here's an example:

• Using if-else statements

  • Another way to handle Selenium exceptions is by using if-else statements.
  • This allows you to check if an element is present before interacting with it. Here's an example:

• Using explicit waits

  • You can also use explicit waits to handle Selenium exceptions.
  • This allows you to wait for an element to become visible or clickable before interacting with it. Here's an example:

Common Exceptions in Selenium WebDriver

Let's take a closer look at some of the most common exceptions in Selenium WebDriver and how to handle them.

• org.openqa.selenium.NoSuchElementException

  • This exception is thrown when the driver is unable to locate an element.

• org.openqa.selenium.NoSuchWindowException

  • This exception is thrown when the driver is unable to switch to a window that does not exist or has been closed.

• org.openqa.selenium.NoSuchFrameException

  • This exception is thrown when the driver is unable to switch to a frame that does not exist or has been removed.

• org.openqa.selenium.NoAlertPresentException

  • This exception is thrown when the driver is unable to interact with an alert that does not exist or has been dismissed.

• org.openqa.selenium.InvalidSelectorException

  • This exception is thrown when the driver is unable to locate an element using an invalid or incorrect selector.

• org.openqa.selenium.ElementNotVisibleException

  • This exception is thrown when the driver is unable to interact with an element that is not visible.

• org.openqa.selenium.ElementNotSelectableException

  • This exception is thrown when the driver is unable to select an element that is not selectable.

• org.openqa.selenium.TimeoutException

  • This exception is thrown when the driver is unable to complete an action within a specified amount of time.

• org.openqa.selenium.NoSuchSessionException

  • This exception is thrown when the driver is unable to communicate with the browser due to a lost or broken connection.

• org.openqa.selenium.StaleElementReferenceException

  • This exception is thrown when the driver is unable to interact with an element that has been modified or removed from the DOM.

Avoiding And Handling Common Exceptions

Now, let's take a closer look at how to handle some of the most common exceptions in Selenium WebDriver.

• org.openqa.selenium.NoSuchElementException:

  • To handle this exception, you can use a try-catch block or an if-else statement to check if the element is present before interacting with it.
  • You can also use explicit waits to wait for the element to become visible. Here's an example:

• org.openqa.selenium.NoSuchWindowException:

  • To handle this exception, you can use a try-catch block to catch the exception and retry the action. Here's an example:

• org.openqa.selenium.NoSuchFrameException:

  • To handle this exception, you can use a try-catch block to catch the exception and retry the action. Here's an example:

• org.openqa.selenium.NoAlertPresentException:

  • To handle this Selenium exception, you can use a try-catch block to catch the exception and retry the action. Here's an example:

• org.openqa.selenium.InvalidSelectorException:

  • Here's an example of how to handle an InvalidSelectorException using a try-catch block in Java:

• org.openqa.selenium.ElementNotVisibleException:

  • To handle this exception in Selenium, you can use explicit waits to wait for the element to become visible or use JavaScript to make the element visible. Here's an example:

• org.openqa.selenium.ElementNotSelectableException:

  • To handle this exception, you can use explicit waits to wait for the element to become selectable or use JavaScript to make the element selectable. Here's an example:

• org.openqa.selenium.TimeoutException:

  • To handle this exception, you can increase the timeout or retry the action. Here's an example:

• org.openqa.selenium.NoSuchSessionException:

  • To handle this exception, you can restart the driver or try running the test again. Here's an example:

• org.openqa.selenium.StaleElementReferenceException:

  • To handle this Selenium exception, you can use explicit waits to wait for the element to become stable or refresh the page. Here's an example: