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Why Do Classical Selectors Often Fail in UI Testing?
Classical test automation relies heavily on DOM-based selectors like XPath or CSS.
These selectors identify UI elements by their position or attributes in the Document Object Model (DOM).
But here’s the issue:
- Even small changes in the DOM (like renaming an ID or class) can break tests.
- This leads to flaky tests that pass or fail unpredictably.
- Debugging becomes painful when selectors are long, technical, and hard to interpret.
When humans test, they visually recognize a "Login" button regardless of HTML changes.Classical automation scripts, however, fail if the DOM structure shifts.
What Are Smart Selectors?
Smart selectors try to bridge this gap by simulating how humans perceive and interact with UI.
They combine visual or relational context with classic selectors to create more resilient tests.
1. OCR (Optical Character Recognition)
OCR scans the UI like a human eye does, recognizing visible text.
- Great for clicking buttons labeled “Submit” or verifying key messages.
- Often combined with DOM selectors to strengthen tests.
2. Picture-in-Picture (PiP) Search
PiP works by matching small image snippets of UI elements across the screen.
- Closer to human perception than strict DOM lookup.
- Useful when there’s no stable DOM reference.
3. Relational Descriptions (Relative Locators)
Instead of selecting an element directly, smart selectors can find elements by their relationship to others.
- Example: Locate an input field under a “Password” label.
- Helps validate UI layout and flow.
How Do These Smart Selectors Help QA Teams?
- They reduce test maintenance by making scripts less sensitive to backend code changes.
- They allow tests to catch visual or spatial issues that DOM selectors miss.
FAQ: Smart Selectors in UI Testing
Can smart selectors replace all XPath or CSS selectors?
Not completely. They work best together—smart selectors add robustness where classic ones fail.
Are these slower to run?
OCR and PiP can slightly increase execution time, but save hours of maintenance by catching issues early.
When should you use them?
Use smart selectors for critical user journeys like login, checkout, or any UI with frequent DOM changes.
Related Reading
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