Shashik worked on modernizing the test infrastructure for Magento extensions, focusing on the magento/magento2-page-builder and magento/inventory repositories. He migrated unit tests from PHPUnit 10 to PHPUnit 12, updating test annotations and mock object creation patterns to align with the latest framework standards. Using PHP and leveraging skills in test-driven development and mocking, Shashik established a consistent PHPUnit 12 baseline across repositories to improve test reliability and CI compatibility. His work addressed both feature development and bug fixes, resulting in more maintainable and robust test suites that support ongoing development and ensure compatibility with evolving testing tools.