如何在单个可执行文件中将数据重定向到stdin？

I am using cxxtest as the test framework for my C++ classes, and would like to figure out a way to simulate sending data to classes which would normally expect to receive it from standard input. I have several different files which I would like to send to the classes during different tests, so redirection from the command line to the test suite executable is not an option. as the test framework for my