Worked on the protocolbuffers/protobuf repository to modernize Rust test assertions, focusing on improving test infrastructure and maintainability. Updated test matchers throughout the Rust test suite, replacing instances of empty with is_empty to align with current Rust testing conventions. This change enhanced test clarity and consistency without altering any underlying protobuf functionality, ensuring continued stability. The work involved skills in Rust, build systems, and testing, and laid the groundwork for future improvements in test suites and CI reliability. By refining test expectations, the developer contributed to a more maintainable codebase while preserving the existing behavior of the protobuf library.