What extra runtime dependencies does this add to python38.dll (use dumpbin /imports python38.dll and grab the DLL filenames)?

Also, winapi methods are public, if undocumented (since they are supposed to reflect the Windows API calls directly, so that documentation should suffice). If you really want an internal test suite helper it should go in its own extension module with a _ prefix.

(Haven't looked too closely at the implementation yet, but when I do, it will be with the view that it is a public API change. Unless you rework it into its own module first.)