New versions starting from 1.0.0 externalize the admin configuration node, so you need to install node-red-contrib-firebase-admin-config before installing and using this node:
npm i node-red-contrib-firebase-admin-config
Also due to naming conflicts, some of the node names have been changed, if you seen a node is not found when starting Node-RED, just delete them from the editor and re-add them from the pallete.
These nodes support Set and Push operations, as well as watching for changes.
cd test && touch my-firebase-service-credential.json
Setup a firebase project, get and paste the service account json to this file.
Then do
npm run test