Fix accidentally skipped test assertion

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 4567dbd..a6f3685 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -5939,7 +5939,9 @@
     } else {
         ret = mbedtls_test_move_handshake_to_state(&client_ep.ssl, &server_ep.ssl, state);
     }
-    TEST_ASSERT(ret == 0 || ret == MBEDTLS_ERR_SSL_WANT_READ || MBEDTLS_ERR_SSL_WANT_WRITE);
+    if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
+        TEST_EQUAL(ret, 0);
+    }
 
     char label[] = "test-label";
     uint8_t key_buffer[24] = { 0 };