Simulate traffic over virtual com port

I'm having a project with Arduino(s) and I would like to build a testing environment so I will be able to do end-to-end integration before testing on the real stuff.

I have a C# program that controls the actions sent to an Arduino, using serial port. The Arduino do some calculations and send back the results back to the C# controller.

I do not want to change the C# program. I do have to implement a program that runs the arudino code and transmit it to a virtual com port I've already created, so the C# program could read it.

Can you please give me some guidance how to write to the virtual com port ? The Arduino is written in C++, so I guess the solution should be implemented in C++ also.

I noticed to the existance of the tcomport, but it's written in Delphi, so I can't see how I can use it with the C++ code.

Thanks