Add lightweight_test_with_fail

test/lightweight_test_with_fail.cpp

@@ -0,0 +1,39 @@
+// Negative test for BOOST_TEST_WITH
+//
+// Copyright 2020 Bjorn Reese
+// Copyright 2020 Peter Dimov
+//
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/lightweight_test.hpp>
+#include <cmath>
+
+template <typename T>
+struct with_tolerance
+{
+    with_tolerance( T tolerance ): tolerance( tolerance )
+	{
+	}
+
+	bool operator()( T lhs, T rhs ) const
+    {
+        return std::abs( lhs - rhs ) <= tolerance;
+    }
+
+private:
+
+	T tolerance;
+};
+
+void test_tolerance_predicate()
+{
+    BOOST_TEST_WITH( 1.0, 1.0 - 1e-6, with_tolerance<double>(1e-7) );
+    BOOST_TEST_WITH( 1.0, 1.0 + 1e-6, with_tolerance<double>(1e-7) );
+}
+
+int main()
+{
+    test_tolerance_predicate();
+    return boost::report_errors() == 2;
+}