Add tests for valid NULL in gcm_free()
diff --git a/tests/suites/test_suite_gcm.function b/tests/suites/test_suite_gcm.function
index 434d42e..1fcb681 100644
--- a/tests/suites/test_suite_gcm.function
+++ b/tests/suites/test_suite_gcm.function
@@ -263,6 +263,15 @@
 }
 /* END_CASE */
 
+/* BEGIN_CASE */
+void gcm_valid_param( )
+{
+    TEST_VALID_PARAM( mbedtls_gcm_free( NULL ) );
+exit:
+    return;
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_SELF_TEST */
 void gcm_selftest(  )
 {