docs(CONTRIBUTING): add section on testing

[jsjoeio]

Checklist

• updated CHANGELOG.md

[codecov]

Codecov Report

Merging #3629 (787d8d5) into main (5f7e9b7) will not change coverage.
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[jawnsy]

Wow!! 🔥 🔥 🔥

I love this, great pointers to help new contributors navigate the codebase and understand how things work

[janiversen]

I am strongly in favor of of the 3 test levels, but I miss a definition of the definition and objective of each level. E.g. integration testing could be seen as the interface to to VScode.

[jsjoeio]

but I miss a definition of the definition and objective of each level. E.g. integration testing could be seen as the interface to to VScode

Great feedback! I think I should clarify this a bit more on what we mean by each.

[janiversen]

LGTM

[jsjoeio]

Sweet! Thanks for the reviews @janiversen @jawnsy - going to merge