Unit tests (gtest?) for C++ Builder VCL applcaiton

I am trying to prepare environment to create unit tests for C++ Borland Builder (XE2) application.
My first choice was gtest.
I am able to write tests for classes which are not related to VCL forms. Problems started when I wanted to write tests for class which include VCL classes, for example:

#include <StdCtrls.hpp>

Did someone know how to compile such class?
I am using Cygwin and basic Makefile like: http://ift.tt/1NZ3WuV.
I have access to Vcl.StdCtrls.dcu, but I am not sure if it is possible to use *.dcu files in gtest.
Do you have any experience with writing unit tests for such application?

Thank you in advance,
Rafał