check_once_cc_ccache_get_principal
check_once_cc_ccache_get_principal(ccache, cc_credentials_v5, "foo/BAR@BAZ.ORG", ccNoError, "trying to get krb5 princ for krb5 ccache");
check_once_cc_ccache_get_principal(ccache, cc_credentials_v5,
cc_int32 check_once_cc_ccache_get_principal(cc_ccache_t ccache, cc_uint32 cred_vers, const char *expected_principal, cc_int32 expected_err, const char *description);