This repository contains a VS Code extension (generated with yo code) but with the integration test suite runner replaced. By default, the generated project uses Mocha, but if you already have Jest or you want to migrate to it, it can be difficult.
The important bits came from this issue: microsoft/vscode-test#37 and this blog post: https://medium.com/@soloydenko/end-to-end-testing-vs-code-extensions-via-jest-828e5edfeb75.
You can always open issues to ask question, but don't waste your time on PR unless asked (or told it would be worth it).