operator overloading << for enum to ostringstream

Question

I have the following macro.

#define STRING_STREAM( data )       \
    ( ( (std::ostringstream&)       \
        ( std::ostringstream( ).seekp( 0, std::ios_base::cur ) << data ) ).str( ) )

I am trying to overload << for an enum:

std::ostringstream& operator<<( std::ostringstream& oStrStream, TestEnum& testEnum )
{
    oStrStream << "TestEnum";
    return oStrStream;
}

When I call STRING_STREAM( testEnum ), it doesn't use the overloaded <<. It prints enums number value.

Answer 1

std::ostream& operator<<( std::ostream& oStrStream, const TestEnum testEnum )
{
    oStrStream << "TestEnum";
    return oStrStream;
}