WordPress plugin and theme testing with PHPUnit integration tests, WP_Mock unit tests, PHPCS coding standards, and CI/CD workflows

WordPress Testing & Quality Assurance progressive disclosure: entry point: summary: "WordPress plugin and theme testing with PHPUnit, WP Mock, PHPCS, and CI/CD for quality assurance" when to use: "Testing WordPress plugins with PHPUnit integration tests" "Unit testing without loading WordPress core (WP Mock)" "Enforcing coding standards with PHPCS" quick start: "Set up PHPUnit with WordPress test suite" "Write unit tests with WP Mock" "Configure PHPCS with WPCS ruleset" Testing Strategy Testing Pyramid for WordPress The WordPress Testing Hierarchy: Test Distribution Guidelines: Unit Tests (60%): Fast, isolated, no WordPress Pure PHP functions Class methods with clear inputs/outputs Business logic without side effects Integration Tests (30%): WordPress loaded tests Database operations Hook/filter interactions Custom post type registration Settings API functionality E2E Tests (10%): Browser automation Critical user workflows Admin panel interactions Frontend form submissions When to Use PHPUnit vs WP Mock Use PHPUnit (Integration Tests) when: ✅ Testing database operations ( $wpdb , post creation, meta data) ✅ Testing WordPress hooks (actions/filters actually firing) ✅ Testing template rendering and output ✅ Testing plugin activation/deactivation logic ✅ Testing with actual WordPress functions Use WP Mock (Unit Tests) when: ✅ Testing pure business logic ✅ Testing functions that call WordPress functions but logic is independent ✅ Need fast test execution (no database setup) ✅ Testing in isolation without side effects ✅ Mocking external API calls Test Coverage Goals Minimum Coverage Requirements: New Code: 80% minimum coverage Critical Paths: 95% coverage (payment processing, authentication, data validation) Legacy Code: Gradual improvement, prioritize high risk areas Public APIs: 100% coverage for all public methods What to Test (Priority Order): 1. Security Functions: Nonce verification, sanitization, capability checks 2. Data Operations: Database CRUD, data validation, transformation 3. Business Logic: Calculations, workflows, state transitions 4. Hook Callbacks: Action/filter handlers 5. Public APIs: REST endpoints, WP CLI commands What NOT to Test: ❌ WordPress core functions (assume they work) ❌ Third party library internals ❌ Simple getters/setters with no logic ❌ Configuration files (theme.json, block.json) PHPUnit Integration Testing WordPress Test Suite Setup Step 1: Install Dependencies Step 2: Install WordPress Test Library Step 3: Configure phpunit.xml.dist WP UnitTestCase Base Class tests/bootstrap.php: Factory Objects for Test Data Using Built in Factories: Available Factory Objects: $this factory post Posts, pages, custom post types $this factory user Users with roles $this factory term Terms (categories, tags, custom taxonomies) $this factory category Categories specifically $this factory tag Tags specifically $this factory comment Comments $this factory blog Multisite blogs Database Fixtures and Teardown setUp() and tearDown() Methods: setUpBeforeClass() and tearDownAfterClass(): Complete Plugin Test Example tests/test plugin functionality.php: WP Mock Unit Testing What is WP Mock and When to Use It WP Mock Purpose: Test PHP code without loading WordPress Mock WordPress functions to return expected values Verify WordPress functions are called with correct arguments Much faster than integration tests (no database setup) When to Use WP Mock: ✅ Perfect for: Pure business logic that calls WordPress functions Data transformation/validation functions Service classes with WordPress dependencies Testing in continuous integration (faster CI builds) ❌ NOT Suitable for: Testing actual database operations Testing hook interactions between plugins Testing template rendering Testing functions that rely on WordPress state Installation and Setup tests/bootstrap wp mock.php: phpunit wp mock.xml.dist: Mocking WordPress Functions tests/unit/test data processor.php: Mocking Filters and Actions Testing add filter() Calls: Testing in Isolation (No WordPress Dependency) Example: Email Service Class: Unit Test Without WordPress: PHPCS & Coding Standards Installing PHPCS and WPCS via Composer (Recommended): .phpcs.xml.dist Configuration Complete Configuration File: Running PHPCS and PHPCBF Command Line Usage: composer.json Scripts: Pre commit Hooks Install pre commit hook (.git/hooks/pre commit): Make hook executable: IDE Integration Visual Studio Code (.vscode/settings.json): PHPStorm Configuration: 1. Go to Settings → PHP → Quality Tools → PHP CodeSniffer 2. Set Configuration path: {PROJECT ROOT}/vendor/bin/phpcs 3. Go to Settings → Editor → Inspections → PHP → Quality Tools 4. Enable "PHP CodeSniffer validation" 5. Set Coding standard: "Custom" 6. Set Path: {PROJECT ROOT}/.phpcs.xml.dist GitHub Actions CI/CD Workflow File Structure .github/workflows/tests.yml: Matrix Testing (Multiple PHP/WP Versions) Strategy Explanation: Matrix Results: Creates 18 test jobs (3 PHP × 6 WordPress versions) Ensures compatibility across supported versions Identifies version specific issues early PHPCS Checks in CI Dedicated PHPCS Job: PHPUnit Test Execution With Code Coverage: Coverage Reporting Codecov Integration: Coveralls Integration: Complete Workflow Example .github/workflows/ci.yml (Production Ready): Testing Best Practices Test Naming Conventions Method Naming Pattern: Examples: Class Naming: Arrange Act Assert Pattern Structure Every Test: Complete Example: Data Providers Purpose: Test same logic with multiple inputs Complex Data Provider: Testing Hooks and Filters Testing add action/add filter: Testing Hook Callbacks: Testing AJAX Handlers AJAX Test Setup: Common Testing Patterns Testing Custom Post Types Testing Settings/Options Testing Database Operations Testing REST API Endpoints Related Skills: When testing WordPress applications, consider these complementary skills (available in the skill library): WordPress Plugin Fundamentals : Core plugin architecture and hooks essential foundation for understanding what to test WordPress Security & Validation : Security patterns and data validation critical for security testing strategies Python pytest Testing : Modern testing patterns concepts applicable to WordPress testing approaches GitHub Actions CI/CD : CI/CD automation integrate WordPress tests into automated pipelines Further Reading: [WordPress PHPUnit Documentation](https://make.wordpress.org/core/handbook/testing/automated testing/writing phpunit tests/) [WP Mock GitHub Repository](https://github.com/10up/wp mock) [WordPress Coding Standards](https://developer.wordpress.org/coding standards/) [PHPUnit Documentation](https://phpunit.de/documentation.html)

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