user32: Implement GetWindowModuleFileName with tests

[Dmitry Timoshkov]

"Reece Dunn" <msclrhd at googlemail.com> wrote:

>> > +    retval = GetWindowModuleFileNameW(hwnd, filenameW, cchFileNameMax);
>> > +    if (retval)
>> > +    {
>> > +        DWORD lasterror = GetLastError();
>> > +        WideCharToMultiByte(CP_ACP, 0, filenameW, -1, lpszFileName, cchFileNameMax, NULL, NULL);
>> > +        SetLastError(lasterror);
>>
>> What's the point of saving/restoring last error value? If WideCharToMultiByte
>> fails you need to return an error in that case, not silently continue.
> 
> The usual model is something like this:
> 
>    SetLastError(0xdeadbeef);
>    WinApiCall();
>    ok(GetLastError() == ERROR_SUCCESS, "WinApiCall failed, expected
> ERROR_SUCCESS, got %d", GetLastError());

In the tests, which is not the case here.

-- 
Dmitry.