Building a Comprehensive Test Suite for gprMax

gprMax, an open-source FDTD electromagnetic simulator used in published research across GPR infrastructure assessment, landmine detection, archaeology, glaciology, and NASA Mars exploration (RIMFAX/Perseverance), currently lacks comprehensive automated testing. This proposal delivers a three-tier test framework: (1) unit tests covering every core Python and Cython module in isolation; (2) integration tests verifying CPU, GPU, and MPI backend consistency and HDF5 I/O correctness; and (3) physics validation tests that compare simulation outputs against known analytical solutions including plane-wave propagation, PML reflection coefficient, energy conservation, and the reciprocity theorem. All tests run automatically on Ubuntu, Windows, and macOS via GitHub Actions on every push to devel. The end-of-summer deliverable is a production-grade, CI-integrated test suite ready for merger into the main gprMax repository.