Need help for unit test about undo

[Regina Henschel]

Hi all,

It is about bug https://bugs.documentfoundation.org/show_bug.cgi?id=128651
The reason is the already discussed behavior of 
SdrObjCustomShape::SetShapRect, so I know how to fix it.

But I do not know, how to make a unit test about undo and redo 
functionality.

Kind regards
Regina