Test if button is drawn properly

[Fabian Maurer]

Hello,

I'm currently investigating https://bugs.winehq.org/show_bug.cgi?id=45246.

in comctl32/button.c in BUTTON_CalcLabelRect:
> if ((infoPtr->u.image && bm.bmWidth == 0 && bm.bmHeight == 0)
>        || (text == NULL || text[0] == '\0'))

This causes the button not to render when an image is set, but the text is null. 
AFAIK a button can have only an image though - handling it like that fixes a 
rendering issue.
But how can I write a test for that, to document that behavior?

Regards,
Fabian Maurer