more compared code following suggestion from Glen Fernandes and testing expected failures

test/lightweight_test_fail9.cpp

@@ -0,0 +1,18 @@
+//
+// Negative test for BOOST_TEST_CSTR_EQ
+//
+// Copyright (c) 2017 Hans Dembinski
+//
+// Distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+//
+
+#include <boost/core/lightweight_test.hpp>
+
+int main()
+{
+    BOOST_TEST_CSTR_EQ("x" , "y");
+
+    return boost::report_errors();
+}