TLDR: WordPress's ecosystem requires automated testing to handle compatibility issues from updates and plugins. Key tools include PHPUnit for unit tests, Selenium and Playwright for end-to-end testing, WP-CLI for setup, and GitHub Actions for CI. Implement comprehensive testing strategies (unit, integration, E2E, regression, cross-browser) to maintain stability and prevent breakage. Best practices involve starting with core features, isolating test environments, keeping tests readable, and using CI for efficiency. Automated testing ensures reliable deployments and stable sites. Start with automated tests to enhance project manageability.
https://www.advancedcustomfields.com/blog/wordpress-automated-testing/