Add Briefcase-specific testing section to write_code docs

[kshivani06]

This PR adds a Briefcase-specific documentation block to
docs/en/how-to/contribute/how/write_code.md using the
testing_additional Jinja block, as discussed in #2238.

This establishes the structure and placement for
Briefcase-specific contribution and testing guidance.
The content will be expanded once the structure is
confirmed.

Feedback welcome.

[kshivani06]

@freakboy3742 I’ve added the requested Jinja block scaffold in
write_code.md. Please let me know if the placement and structure
look good before I expand the content.

[freakboy3742]

You've got the right place - however, as you may have noticed from the CI pass, the escaping you've added for _ characters means the documentation no longer builds. You're also missing a towncrier changenote, and the PR isn't passing CI. These issues are all covered in the contribution guide; I'd suggest having a read of that guide.

[kshivani06]

Thanks for pointing that out. The escaping and towncrier issues are fixed and CI is now passing.

I’ll add the Briefcase-specific content only within the "testing_additional" block, keeping the rest unchanged. Please let me know if that works.

[freakboy3742]

Why have you deleted the title from the document?

[freakboy3742]

The build is now succeeding; however, as noted inline, you've deleted the title from the page. The title for the new section is at level 2, rather than level 3; and there's also a lot of extra blank lines - one line between statements is more than enough.

The ReadTheDocs CI job gives you a sample rendering of what the page currently looks like; that's worth checking out in addition to your own local build.

However, other than those changes, it's now ready for you to add new content.

[freakboy3742]

Suggested change

	## Briefcase-specific content
	### Briefcase-specific content

[kshivani06]

I’ve pushed the requested structural fixes (restored the title, adjusted the heading level to ###, and cleaned up spacing).

Just a quick note: I have been unable to successfully run tox -e docs on my local Windows machine with Python 3.12. The build consistently fails during the environment setup due to a dependency issue. The failure appears to be related to the installation of the tzdata dependency within the tox virtual environment on the Windows platform. This seems to be a common environment-specific conflict between tzdata and certain versions of Python/Windows. Since the docs CI is passing, I’m relying on CI as the source of truth for now.

Please let me know if you’d prefer a different approach.

[kattni]

@kshivani06 You're on the right track. You can go ahead and start adding content, if you like.

I want to let you know that the core team is currently on holiday leave, so response times are going to be slower for the next few weeks. You can likely expect a response within eight days, possibly sooner, as we'll be checking in weekly. We appreciate your patience.

[kshivani06]

Hi ,

I’ve added all the requested documentation content covering:

• the range of templates used by Briefcase at runtime,
• testing wizard template changes,
• testing platform template changes using template and template_branch,
• and handling cases where template changes depend on Briefcase changes.

The remaining CI failure appears to be unrelated to the documentation content and is occurring during the docs build due to missing shared macro templates in the docs tooling, affecting multiple existing pages.

Please let me know if you’d like any adjustments to the content, additional clarification, or further sections added. I’m happy to update this as needed.

Thanks!

[kattni]

@kshivani06 Hello. A reminder that the team is on holiday leave, so it'll be a bit before we can respond.

However, before we can review, the PR needs to be passing CI.

The documentation failures are because you need to merge main into this PR. That should fix it. There is also a merge conflict on the file you're editing; I believe it is only a filename change. Please merge main and fix the conflict. Let me know if you need assistance.

[kshivani06]

"Hi @kattni, thank you for the guidance! I have successfully merged upstream/main into my branch and resolved the filename conflicts. The documentation build is now passing. Happy holidays to the team!"

[freakboy3742]

This is a great first draft! I've put some brief comments inline; but I've also pushed an update that addresses them, as it's a little easier to make the changes directly rather than suggest them in GitHub.

Thanks for the PR - I'll get another set of eyeballs to check this to make sure I haven't introduced any extra typos; but otherwise, this is a great update to the docs.

[freakboy3742]

This should probably be at level 4 so that there's some structure to this section about templates.

[freakboy3742]

Local file usage is also important here - possibly more important for local testing purposes.

[freakboy3742]

As above, local file changes are also important.

[freakboy3742]

We can reference the configuration options directly with [template][] syntax.

[freakboy3742]

This isn't needed - this is what briefcase-repo: and briefcase-ref: are for.

[kattni]

Thank you @kshivani06 for the contribution!

@freakboy3742 Your final updates look good to me.

All issues have been addressed.

[kshivani06]

Thank you for the review and guidance