Method Session

tests/catch.h:6289–6297

        struct OnUnusedOptions { enum DoWhat { Ignore, Fail }; };

        Session()
        : m_cli( makeCommandLineParser() ) {
            if( alreadyInstantiated ) {
                std::string msg = "Only one instance of Catch::Session can ever be used";
                Catch::cerr() << msg << std::endl;
                throw std::logic_error( msg );
            }
            alreadyInstantiated = true;
        }
        ~Session() {
            Catch::cleanUp();
        }