check_once_cc_ccache_store_credentials
check_once_cc_ccache_store_credentials(ccache, &creds_union, ccNoError, "ok creds");
check_once_cc_ccache_store_credentials(ccache, NULL, ccErrBadParam, "NULL creds param");
check_once_cc_ccache_store_credentials(ccache, &creds_union, ccErrBadParam, "invalid creds (NULL client string)");
check_once_cc_ccache_store_credentials(ccache, &creds_union, ccErrInvalidCCache, "invalid ccache");
cc_int32 check_once_cc_ccache_store_credentials(cc_ccache_t ccache, const cc_credentials_union *credentials, cc_int32 expected_err, const char *description);