Need help on how to insert a layer into a Draw document in a unit test

Hi all,

I'm working on 
https://bugs.documentfoundation.org/show_bug.cgi?id=119392. I have a 
solution for it. Now I need a unit test. I need to do:
1. Load a Draw document, which has two user defined layers with 
non-default settings for visible/printable/locked.
2. Insert a new layer between these two layers, which has non-default 
settings for visible/printable/locked.
3. Save the document.
4a) Examine the saved file, whether it has the correct items in the 
setting.xml or
4b) Reload the file and make sure the visible/printable/locked settings 
are correct for each of the user defined layers.

Is there a test, where I can look, how to make step 2? A guide for step 
4b is not quite necessary because I know how to do step 4a, but would be 
nice to have.

Kind regards
Regina