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, etc.) for all modules except the
    SSL modules.

compat
    The 'tests/compat.sh' script checks interoperability with OpenSSL for every
    ciphersuite, in every version, using client authentication or not.  For
    each ciphersuite/version it performs a full handshake and a small data
    exchange.

ssl_opt
    The 'tests/ssl-opt.sh' script checks various options and/or operations not
    covered by compat.sh: session resumption (using session cache or tickets),
    renegotiation, SNI, other extensions, etc.