How to make a unit test which involves a dialog

[Regina Henschel]

Hi all,

the patch for which I want to make a unit test is in 
https://gerrit.libreoffice.org/c/core/+/104234

The error is produced, when you set a new width or height for a 
horizontal or vertical line in the Position&Size dialog in Calc. So how 
can I use the Position&Size dialog in a unit test? Is it possible with C++?

Kind regards
Regina