docs: add new documentation related to testing style guide and testing template

[EshaanAgg]

Summary

Adds

• Style guide for testing
• A test template and common ways to use the mocks

References

Slack Discussion

Reviewer guidance

---

Testing checklist

• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical user journeys are covered by Gherkin stories
• Critical and brittle code paths are covered by unit tests

PR process

• PR has the correct target branch and milestone
• PR has 'needs review' or 'work-in-progress' label
• If PR is ready for review, a reviewer has been added. (Don't use 'Assignees')
• If this is an important user-facing change, PR or related issue has a 'changelog' label
• If this includes an internal dependency change, a link to the diff is provided

Reviewer checklist

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md

[github-actions]

Build Artifacts

Asset type	Download link
PEX file	kolibri-.pex
Windows Installer (EXE)	kolibri-0.16.2b1.dev0+git.1101.g7eb2f443-windows-setup-unsigned.exe
Debian Package	kolibri_0.16.2b1.dev0+git.1101.g7eb2f443-0ubuntu1_all.deb
Mac Installer (DMG)	kolibri-0.16.2b1.dev0+git.1101.g7eb2f443-0.4.1.dmg
Android Package (APK)	kolibri-0.16.2b1.dev0+git.1101.g7eb2f443-0.1.2-debug.apk
TAR file	kolibri-0.16.2b1.dev0+git.1101.g7eb2f443.tar.gz
WHL file	kolibri-0.16.2b1.dev0+git.1101.g7eb2f443-py2.py3-none-any.whl

[AlexVelezLl]

Thanks for all your work here @EshaanAgg! This is looking great, these are some thoughts from an initial reading. But it's definitely looking good.

[EshaanAgg]

Thanks, @MisRob and @AlexVelezLl, for all the help. I have updated the documentation as per the review comments. I also took the liberty to make two more changes:

• Remove the imports for VueRouter from each of the sample tests and templates, as the same should be fixed by Fix Vue Tesing Library routes bug #12105
• As discussed in a review comment of tests: add tests for some files in ContentRenderer #12056, it is better that while mocking composables we pass the composable related mocking data in a separate property to the render function. I have updated that recommendation too.

Let me know if you would like to see something else added!

[AlexVelezLl]

Hi @EshaanAgg! Thank you for all your great work here. Sorry for the delay in the review. And Sorry for the back and forth. I think this will be the last before approval from my side. It's pretty polished already 🎉.

[AlexVelezLl]

Thanks for all your hard work here @EshaanAgg!! 🎉. In the future we could edit the documentation and cover some point that we might be missing, but for now it looks pretty good. The style guide shows the what and how quite well. The testing template looks quite good and complete for multiple cases, and the structure in general seems adequate and easy to follow!! LGTM! Thank you 🚀🚀🚀.