Do unit tests on Debian Servers/Build system?

[c.buhtz@posteo.jp]

Hello,

I try to understand some basics about debian packaging Python 
applications and the upload and test process.
My question in short: When (at which time point in the process of 
packaging python applications for Debian) do the Python unit tests run?

I know about the Salsa instance. Maintainers do create deb files out of 
it and then upload them to the official package repository.

Starting from tracker.debian.org I can link to a lot of status packages 
indicating success or problems; e.g. Linitian, CI, ...
No where I was able to find an indicator about if unit tests are 
successful or not.

Do such tests to run at the Debian Servers? Or do the maintainers only 
start them at their own local machines? Is this a manual step in the 
process?
If they run automatically when do they run? Before or after the deb 
files is created? If it is the latter then the test_*.py files need to 
be contained in the deb file I assume.

Thanks in advance
Christian Buhtz