The changes made in https://git.yoctoproject.org/poky/commit/?id=207a5a21d38f4ed1b71aed0158ce067b57502cc7 revealed that the vast majority of patchtest's test suite is focused on testing the mbox portion of a series. While there is no strict demand for coverage in the other areas, it would be good to have more comprehensive testing for embedded patches, recipe metadata, and general code quality/linting. Inspiration for what can be added may be found in some of the Yocto docs, e.g. the contributor guide.