11 April 2024 Leave a comment Tech-Help
When automating tests with Cypress, encountering errors from the application under test is not uncommon. If you’re testing your application and come across an error message indicating that the error originated from your application code, not from Cypress, don’t worry. This guide will help you to handle such exceptions so you can continue with your testing workflow effectively.
Understanding the Error
When you run a test that interacts with a web application, such as clicking a button or submitting a form, and the application throws an error that is not caught within the application itself, Cypress will by default fail the test. This is because Cypress detects uncaught exceptions as potential issues that need to be addressed.
Handling Uncaught Exceptions
To prevent Cypress from failing the test upon encountering an uncaught exception, you can instruct Cypress to ignore these exceptions temporarily. This can be particularly useful when you know that the exception does not impact the test outcome, or when you want to test the application’s behavior in the presence of an exception.
Here’s how you can handle uncaught exceptions:
- Add the following code to your
support/index.jsfile:
import './commands'
Cypress.on('uncaught:exception', (err, runnable) => {
// returning false here prevents Cypress from failing the test
return false
})
This code snippet installs a global handler that suppresses all uncaught exceptions for the duration of the test run. By returning false, you instruct Cypress not to fail the test when an uncaught exception occurs.
Applying a More Targeted Approach
While the global handler can be useful, it may not always be the best approach, as it ignores all exceptions that occur during the test run. A more targeted approach involves handling exceptions on a per-test basis, which can be accomplished using the following code:
it('my test', () => {
cy.once('uncaught:exception', () => false);
// actions that may cause exception
cy.get('body').click();
});
This code snippet binds an exception handler to just the current test by using the cy.once method. It ensures that any uncaught exception that occurs during this specific test does not cause the test to fail.
Conclusion
Dealing with uncaught exceptions in Cypress tests requires a careful approach. While ignoring exceptions might help in certain scenarios, always consider the implications of doing so and use this approach judiciously. Remember that uncaught exceptions could indicate issues in the application that may need to be addressed. Therefore, each exception should be analyzed on a case-by-case basis to decide the most appropriate handling strategy.
