How to catch the output which goes to stdout

#define BOOST_TEST_DYN_LINK
#define BOOST_TEST_MAIN

#include <boost/test/unit_test.hpp>
#include <boost/test/output_test_stream.hpp>
#include <iostream>

BOOST_AUTO_TEST_SUITE( TestSuite1 )

struct cout_redirect {
    cout_redirect( std::streambuf * new_buffer )
        : old( std::cout.rdbuf( new_buffer ) )
    { }

    ~cout_redirect( ) {
        std::cout.rdbuf( old );
    }

private:
    std::streambuf * old;
};

BOOST_AUTO_TEST_CASE( test1 )
{
    boost::test_tools::output_test_stream output;
    {
        cout_redirect guard( output.rdbuf( ) );

        std::cout << "Test" << std::endl;
    }

    BOOST_CHECK( output.is_equal( "Test\n" ) ); 
}

BOOST_AUTO_TEST_SUITE_END()

g++ -I/Users/uhlig/software/SnowLeo/fair/fairsoft/apr13/include -L/Users/uhlig/software/SnowLeo/fair/fairsoft/apr13/lib  -lboost_unit_test_framework boost_test_example.cxx 
DYLD_LIBRARY_PATH=/Users/uhlig/software/SnowLeo/fair/fairsoft/apr13/lib ./a.out