C++ sample: Implementation of a simulated object

// Assume you have an arbitrary error type within your SUT
// (for simplicity here modeled as int)
using SpecificErrorType = int;

namespace TestToolBox
{
    inline std::string MakeReturnValue(
        SpecificErrorType&          out_retVal,
        bool                        in_simulateFailure,
        std::string const &         in_methodName, // not used here
        TTB::SimulatedObjectBase const * in_pObject)    // not used here
    {
        out_retVal = SpecificErrorType();
        if (in_simulateFailure) out_retVal = -1;
        return ""; // optionally give info for test output
    };
}
class SomeSimulatedObject : public TTB::RegisteredSimulatedObject
{
public:
    SomeSimulatedObject(std::string const & in_name)
        : TTB::RegisteredSimulatedObject(in_name, TTB_CLASS_NAME)
    {}

    void DoSomething()
    {
        bool xValDefined = _IsOptionSet("xVal", TTB_FUNC_NAME);
        double xVal = _GetOptionValue<double>("xVal", TTB_FUNC_NAME);
        TTB_METHOD_CALL1("    xVal=" << xVal << (xValDefined ? "" : " (xVal not defined)"));
    }

    void DoSomethingElse() const
    {
        double xVal = _GetOptionValue<double>("xVal", TTB_FUNC_NAME);
        TTB_METHOD_CALL1("xVal=" << xVal);
    }

    void DoSomethingWithAccessToCommandLine() const
    {
        auto yVal = TestToolBox::TheEnvironment()->GetCommandLineOptionVal<double>("-yVal");
        TTB_METHOD_CALL1("yVal=" << yVal);
    }

    SpecificErrorType CalculateSomething(int in_val, int& out_val)
    {
        // Remark: 3rd param is a lambda function which is called
        // immediately before leaving function (i.e. after a possible halt
        // of function call is continued)
        return TTB_METHOD_CALL_RET3(SpecificErrorType, "in_val=" << in_val,
        {
            // Calculate out val
            if (_WasError("CalculateSomething"))
                out_val = -99;
            else
                out_val = 2 * in_val;
            // optional output string
            return TTB_STRING_S("out_val=" << out_val);
        });
    }
};