WooCommerce Backend Development

This skill provides guidance for developing WooCommerce backend PHP code according to project standards and conventions.

When to Use This Skill

ALWAYS invoke this skill before:

• Writing new PHP unit tests (*Test.php files)
• Creating new PHP classes
• Modifying existing backend PHP code
• Adding hooks or filters

Instructions

Follow WooCommerce project conventions when adding or modifying backend PHP code:

1. Creating new code structures: See [file-entities.md](file-entities.md) for conventions on creating classes and organizing files (but for new unit test files see [unit-tests.md](unit-tests.md)).
2. Naming conventions: See [code-entities.md](code-entities.md) for naming methods, variables, and parameters
3. Coding style: See [coding-conventions.md](coding-conventions.md) for general coding standards and best practices
4. Type annotations: See [type-annotations.md](type-annotations.md) for PHPStan-aware PHPDoc annotations
5. Working with hooks: See [hooks.md](hooks.md) for hook callback conventions and documentation
6. Dependency injection: See [dependency-injection.md](dependency-injection.md) for DI container usage
7. Data integrity: See [data-integrity.md](data-integrity.md) for ensuring data integrity when performing CRUD operations
8. Writing tests: See [unit-tests.md](unit-tests.md) for unit testing conventions

Key Principles

• Always follow WordPress Coding Standards
• Use class methods instead of standalone functions
• Place new internal classes in src/Internal/ by default
• Use PSR-4 autoloading with Automattic\WooCommerce namespace
• Write comprehensive unit tests for new functionality
• Run linting and tests before committing changes

Version Information

To determine the next WooCommerce version number for @since annotations:

• Read the $version property in includes/class-woocommerce.php on the trunk branch
• Remove the -dev suffix if present
• Example: If trunk shows 10.4.0-dev, use @since 10.4.0
• Note: When reviewing PRs against trunk, the version in trunk is correct even if it seems "future" relative to released versions