Worked on enhancing Windows build-system support in the denoland/chromium_build repository by enabling test-specific configurations through improved propagation of testonly flags. Focused on build system configuration using GNI, the work ensured that testonly attributes from MIDL templates flowed seamlessly to generated IDL actions and source sets. This approach allowed test-only targets to be defined with minimal changes to existing build files, reducing manual maintenance and the risk of misconfiguration. By streamlining the management of test builds, the changes established a scalable foundation for future test-oriented features in Windows development, supporting more reliable and efficient test pipelines across the project.