Unittest in a windows app

[Dan Nestor via Digitalmars-d-learn]

I managed to isolate the problem to the following. Program 1 
below works (displays unit test failure when run), while program 
2 does not.

***** Program 1 *****

import std.stdio;

unittest
{
     assert(false);
}

void main()
{
     writeln("Hello D-World!");
}

***** Program 2 *****

module winmain;

import core.sys.windows.windows;

unittest {
     assert(false);
}

extern (Windows)
int WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR
lpCmdLine, int nCmdShow)
{
     return 0;
}