Page objects are a K4 learning objective on the A4Q Selenium 4 Tester exam. Here is the four-layer model, the Selenium project's own rules, and the page-object-vs-wrapper trap that scenario questions are built on.
CSS or XPath is the wrong first question. What decides whether a locator survives the next release is what it is anchored to — and that is exactly the judgement the A4Q Selenium Tester Foundation exam asks you to make.
Guía completa 2026 de la certificación A4Q Certified Selenium 4 Tester Foundation: qué es, el formato del examen, el programa completo, qué cambió con Selenium 4 y a quién le conviene.