Drupal Testing

I need to...	Guide	Summary
Understand which testing frameworks are available	Testing Framework Overview	Every Drupal module should include automated testing. Use this guide to understand the five testing frameworks Drupal provides and when each is appropriate.
Choose the right test type for my module	Framework Selection Decision Matrix	Use this guide when planning testing coverage for a new module or deciding which test type to write for specific functionality.
Write tests for pure PHP logic	PHPUnit Unit Tests	Write Unit tests for pure PHP logic that has no Drupal dependencies: calculations, data transformations, validation logic, utility functions, and algorithm implementations.
Write tests for services and database integration	PHPUnit Kernel Tests	Write Kernel tests when you need to test integration with Drupal services, database operations, entity CRUD, or service container interactions without needing a full Drupal installation.
Write tests for admin forms and user workflows	PHPUnit Functional Tests	Write Functional tests for complete user workflows: admin configuration forms, content creation/editing, user registration/login, permission testing, and any feature requiring HTTP requests and responses.
Write tests for AJAX and JavaScript interactions	PHPUnit FunctionalJavascript Tests	Write FunctionalJavascript tests only when testing features that require JavaScript execution: AJAX form elements, autocomplete fields, modal dialogs, drag-and-drop interfaces, or client-side validation.
Measure performance impact of my module	Gander Performance Testing	Write Gander performance tests for modules with site-wide performance impact: event subscribers that fire on every request, cache invalidation logic, bulk operations, or features that execute complex queries.
Plan testing coverage for a new module	Progressive Testing Strategy	Use this progressive approach when building testing coverage for a new module or improving coverage for an existing module. Start simple and add complexity as the module matures.
Set up PHPUnit configuration	Testing Infrastructure Setup	Configure phpunit.xml and composer.json for Drupal module testing. Drupal 11 uses PHPUnit ^11.5 (via drupal/core-dev) with the PHPUnit 11 schema and element; Drupal 10 uses PHPUnit ^9.x — never declare phpunit/phpunit directly to avoid version conflicts.
Follow security and performance best practices	Best Practices & Anti-Patterns	Consult this guide when writing tests, reviewing code, or establishing testing standards for your team.
Run tests from the command line	Running and Debugging Tests	Use this guide when executing tests locally or in CI/CD, or when debugging failing tests.