This code is an example of how to upload images to test.wikipedia.org. The code shows how metadata templates are just included directly into the comments parameter of the upload action against the wiki API.
The Wiki documentation for wikimedia is not very clear about how to include data during the upload process. I originally discover this by applying edits to an already uploaded image.
In edit the pages (the files page) content can be edited with different argumetns including: text, appendtext, prependtext, or even a combination of section with sectiontitle and text.
Although I tried to implement the pywikibot to run my objective, the documentation was not as friendly as the wiki API.
I recommend creating a but user and credentials to run any API software.
Read more about Bots at https://en.wikipedia.org/wiki/Wikipedia:Bots.
Create your own bot at https://www.mediawiki.org/wiki/Special:BotPasswords.