improve code style

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 374e1a2..63929d8 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -215,7 +215,7 @@
      */
     if (server_age > MBEDTLS_SSL_TLS1_3_MAX_ALLOWED_TICKET_LIFETIME * 1000) {
         MBEDTLS_SSL_DEBUG_MSG(
-            3, ("Ticket age exceeds limitation ticket_age=%" MBEDTLS_PRINTF_MS_TIME,
+            3, ("Ticket age exceeds limitation ticket_age = %" MBEDTLS_PRINTF_MS_TIME,
                 server_age));
         goto exit;
     }
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 23f0ff9..fb2ae54 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -2185,19 +2185,25 @@
     ((void) tls_version);
     ((void) ticket_len);
     ((void) crt_file);
-#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
-    if (tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
-        TEST_ASSERT(mbedtls_test_ssl_tls13_populate_session(
-                        &session, 0, endpoint_type) == 0);
-    }
-#endif
 
-#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
-    if (tls_version == MBEDTLS_SSL_VERSION_TLS1_2) {
-        TEST_ASSERT(mbedtls_test_ssl_tls12_populate_session(
-                        &session, ticket_len, crt_file) == 0);
-    }
+    switch (tls_version) {
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
+        case MBEDTLS_SSL_VERSION_TLS1_3:
+            TEST_ASSERT(mbedtls_test_ssl_tls13_populate_session(
+                            &session, 0, endpoint_type) == 0);
+            break;
 #endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        case MBEDTLS_SSL_VERSION_TLS1_2:
+            TEST_ASSERT(mbedtls_test_ssl_tls12_populate_session(
+                            &session, ticket_len, crt_file) == 0);
+            break;
+#endif
+        default:
+            /* should never happen */
+            TEST_ASSERT(0);
+            break;
+    }
 
     TEST_ASSERT(mbedtls_ssl_session_save(&session, NULL, 0, &good_len)
                 == MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL);
@@ -2303,19 +2309,25 @@
     USE_PSA_INIT();
     ((void) endpoint_type);
     ((void) tls_version);
-#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
-    if (tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
-        TEST_ASSERT(mbedtls_test_ssl_tls13_populate_session(
-                        &session, 0, endpoint_type) == 0);
-    }
-#endif
 
-#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
-    if (tls_version == MBEDTLS_SSL_VERSION_TLS1_2) {
-        TEST_ASSERT(mbedtls_test_ssl_tls12_populate_session(
-                        &session, 0, NULL) == 0);
-    }
+    switch (tls_version) {
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
+        case MBEDTLS_SSL_VERSION_TLS1_3:
+            TEST_ASSERT(mbedtls_test_ssl_tls13_populate_session(
+                            &session, 0, endpoint_type) == 0);
+            break;
 #endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        case MBEDTLS_SSL_VERSION_TLS1_2:
+            TEST_ASSERT(mbedtls_test_ssl_tls12_populate_session(
+                            &session, 0, NULL) == 0);
+            break;
+#endif
+        default:
+            /* should never happen */
+            TEST_ASSERT(0);
+            break;
+    }
 
     /* Infer length of serialized session. */
     TEST_ASSERT(mbedtls_ssl_session_save(&session,