Lim Sim contributed to DEFRA’s btms-gateway and btms-backend repositories by enhancing test coverage and improving backend reliability. Over two months, Lim expanded XML-to-JSON converter tests to handle complex nested data, introduced new scenario generators for unmatched CHED records, and addressed string-to-enum serialization issues using C# and JSON. The work included refactoring test infrastructure, automating data-driven tests, and cleaning up extraneous code to improve maintainability and CI reliability. Lim’s approach emphasized robust integration and unit testing, leveraging xUnit and XML processing to ensure accurate data transformations and resilient backend workflows, resulting in deeper, more reliable automated quality assurance.