Скачать или смотреть Troubleshooting Cypress data-testid not found

This guide explores how to resolve issues with Cypress failing to find elements using `data-testid` selectors, particularly those inside shadow DOMs.
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This video is based on the question https://stackoverflow.com/q/73366775/ asked by the user 'ElVincitore' ( https://stackoverflow.com/u/13340923/ ) and on the answer https://stackoverflow.com/a/73367439/ provided by the user 'Fody' ( https://stackoverflow.com/u/16997707/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting Cypress data-testid not found

When using Cypress for automated testing, encountering the issue where your tests can't find elements by their data-testid can be quite frustrating. Imagine you've written a test to click a privacy settings button, but when you run it, Cypress fails to locate that button. This problem is often compounded when the button is nestled inside a shadow DOM, which isn’t always visible when the test starts.

Understanding the Problem

In the context of web applications, particularly those utilizing shadow DOMs, certain elements may not be available at all times. Let's say you want to click a button with the data-testid='uc-accept-all-button'. Here's a simplified example of how your test code might look:

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However, when you execute this test, you encounter an error because Cypress can’t find the button. The main reason for this is that:

The button may not be consistently displayed on the page.

If you click the "Accept All" button once, it might not show up on subsequent visits.

Solution Overview

The solution involves polling for the button within the shadow root of the containing element. This ensures your test waits until the button is actually rendered on the page before attempting a click.

Step-by-step Implementation

Create a Polling Function:
Write a recursive function that will check for the existence of the button inside the shadow DOM. This will keep attempting to find the button for a specified period (e.g., 4 seconds).

[[See Video to Reveal this Text or Code Snippet]]

Trigger the Function:
Call this function after visiting the web page.

[[See Video to Reveal this Text or Code Snippet]]

Important Considerations

Handling Shadow DOMs: You cannot rely solely on Cypress’s includeShadowDom feature because the shadow root might not always be present when tests run. By implementing the polling logic, you accommodate the asynchronous nature of the DOM updates.

Incremental Waiting: Using cy.wait() with smaller increments ensures that the test doesn’t hang indefinitely and can respond effectively to changes in the DOM structure.

Conclusion

Using Cypress for testing can sometimes lead to hurdles, especially when dealing with elements that reside in shadow DOMs. By implementing a polling mechanism, you can effectively handle cases where buttons may not be present immediately. This approach allows your tests to be more resilient and less prone to errors caused by timing issues.

Happy Testing!