Principle:Nightwatchjs Nightwatch Page Object Structure
| Knowledge Sources | |
|---|---|
| Domains | Testing, Design_Patterns, Page_Object_Model |
| Last Updated | 2026-02-12 00:00 GMT |
Overview
A design pattern that encapsulates web page structure and behavior into reusable objects, separating test logic from page-specific implementation details.
Description
The Page Object Pattern is a test design pattern that creates an abstraction layer between tests and the web application's UI. Each page (or significant component) of the application is represented by a class/module that exposes the page's elements, sections, and operations as a clean API. This decouples tests from page structure: when the UI changes, only the page object needs updating, not every test that interacts with that page.
A page object typically defines: a URL for navigation, elements as named selectors, sections as logical groupings of elements, and commands as reusable page-specific operations.
Usage
Use the Page Object Pattern when building a test suite with multiple tests that interact with the same pages. It is especially valuable for large applications where UI selectors change frequently, as it centralizes selector maintenance.
Theoretical Basis
The pattern follows the separation of concerns principle:
- Page Objects own the knowledge of page structure (selectors, URLs)
- Tests own the knowledge of test scenarios (what to verify)
- Commands encapsulate multi-step interactions into single methods
// Pseudocode: Page Object structure
PageObject = {
url: 'target URL for navigation',
elements: { name: selector }, // Element catalog
sections: { name: { selector, elements } }, // Nested groups
commands: [{ methodName() {} }] // Reusable operations
}