Does anyone use testlib on cygwin + g++?

It gives a compilation error at the 434th line:

_setmode(_fileno(file), O_BINARY); ``

I know two ways to fix this issue:

• Comment out the 434th line. However, it disables this line and I'm not sure whether this is a good way.

• Add <io.h> to testlib. However, it works only on Windows.

How to fix the compilation error in a better way?