Add tests for enum helper

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 5968501..d401aea 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -1663,7 +1663,9 @@
 {
     int ret = 0;
 
-    MBEDTLS_SSL_DEBUG_MSG( 2, ( "tls13 client state: %d", ssl->state ) );
+    MBEDTLS_SSL_DEBUG_MSG( 2, ( "tls13 client state: %s(%d)",
+                                mbedtls_ssl_states_str( ssl->state ),
+                                ssl->state ) );
 
     switch( ssl->state )
     {