SELENIUM Study Guide 2026

The Page Object Model (POM) is a design pattern in Selenium that creates an object repository for UI elements. Each web page is represented as a class, with its elements defined as variables, promoting reusable and maintainable code. This approach reduces code duplication and simplifies test script maintenance when UI changes occur, making tests more robust and easier to manage.

Topological sort is only possible on a Directed Acyclic Graph; a cycle means no valid ordering of dependencies exists.

Factory patterns decouple browser creation logic from test code, returning the appropriate WebDriver subclass based on a configuration parameter without if-else chains in tests.

node-max-sessions caps concurrency on a single node to prevent resource exhaustion from too many simultaneous browser instances.

Log analysis is an invaluable technique in Selenium test debugging, as it involves reviewing the output logs generated during test execution. These logs provide detailed information about each step, including actions performed, errors encountered, and system states. By analyzing these patterns and error messages, testers can quickly pinpoint the root cause of failures and effectively troubleshoot issues in their test scripts, improving debugging efficiency.

An LRU cache combines a HashMap for O(1) key lookup with a doubly linked list to track recency and evict the least-recently-used entry in O(1).