We use yarn to install NPM packages.
If you do not have yarn, you can obtain it with npm i -g yarn.
Simply run yarn in this directory to install dependencies.
We recommend doing development within VS Code, with the Open Folder pointing at this directory rather than the repo root. The folder recommends several VS Code extensions to install.
Run yarn build in this directory to transpile the Typescript files to Javascript.
Run yarn test in this directory to run tests.
You must have transpiled first (using yarn build or yarn tsc).
Using yarn watch is a good way to ensure tsc has run with your changes automatically so you can run tests whenever you want.
You can also run tests from the (jest) Test Explorer in VS Code.