Developed enhancements to the parallel testing framework for MPI-enabled code in the gusto repository, focusing on improving reliability and scalability within the Firedrake ecosystem. The work involved restructuring test execution to support concurrent runs using MPI, introducing a parallel test runner API that accelerates feedback and enables more scalable validation of parallel code paths. Addressed instability in Ubuntu continuous integration by moving mpiexec outside of pytest, which reduced flaky test behavior and improved reproducibility. All changes were implemented in Python, leveraging parallel computing concepts and Makefile scripting to ensure robust, maintainable testing workflows for multi-processor environments without introducing new bugs.