test_suites
    The various 'test_suite_XXX' programs from the 'tests' directory, executed
    using 'make check' (Unix make) or 'make test' (Cmake), include test cases
    (reference test vectors, sanity checks, malformed input for parsing
    functions, etc.) for all modules.

selftests
    The 'programs/test/selftest' program runs the 'XXX_self_test()' functions
    of each individual module. Most of them are included in the respective
    test suite, but some slower ones are only included here.