Worked on the apache/datafusion-comet repository to enhance test coverage for null semantics in the array_contains function, focusing on improving overall quality and regression safety. Addressed a key bug by developing comprehensive SQL-based tests that validated array_contains behavior across a range of null-handling scenarios, ensuring consistent and reliable results even in edge cases. Emphasized traceability by linking all changes to a specific issue for future audits, supporting maintainability and transparency. Leveraged skills in SQL and testing to strengthen the reliability of the test suite, contributing to more robust data processing workflows and reducing the risk of undetected regressions in future releases.