Documentation: Document Status of Percy (#8424)

* Documention: Document Status of Percy

* Apply suggestions from code review

Co-authored-by: Vaidehi Joshi <vaidehi.sj@gmail.com>

Co-authored-by: Vaidehi Joshi <vaidehi.sj@gmail.com>

docs/tests/readme.md

@@ -27,6 +27,8 @@ We use the following testing tools:
   testing Preact components
 - [**SimpleCov**](https://github.com/colszowka/simplecov) for tracking overall
   test coverage on the backend
+- [**Percy**](https://percy.io/) for visual regression testing. Currently
+  inactive.
 
 We strive to provide tests for each pull request that adds new features or fixes
 a bug. Ideally, we test the functionality of the frontend and the backed.

docs/tests/regression-tests.md

@@ -33,3 +33,15 @@ helping to ensure your patch fixes the bug.
 [acceptance_tests]: /tests/acceptance-tests/
 [integration_tests]: /tests/integration-tests/
 [ci]: /deployment/
+
+# [Percy](https://percy.io/)
+
+Percy is a tool that can be used to do visual regression testing. Percy renders
+and compares snapshots across browsers and screens to detect, highlight, and
+group visual differences. This allows users to quickly find visual regression issues. Currently,
+**Percy is inactive in our test suite** due to some integration issues. We are
+not sure if we will try to reimplement it in the future so for now we have
+decided to leave the code as is. You will notice `Percy.snapshot` being called
+in multiple tests. That method has been stubbed in our `rails_helper.rb` file to ensure that
+we don't waste resources taking snapshots. You will also notice some specs that
+only take Percy snapshots have been commented out.