Simple Firestore emulator check

const firebase = require("@firebase/testing");

async function main() {
  const projectId = "my-test-project";
  await firebase.loadFirestoreRules({
    projectId,
    rules: `
      service cloud.firestore {
        match /databases/{database}/documents {
          match /users/{company} {
            allow create;
            allow update: if request.auth.uid != null;
          }
        }
      }
    `
  });
  const app = firebase.initializeTestApp({
    projectId,
    auth: {
      uid: "ryan",
      email: "ryan@example.com"
    }
  });
  await app.firestore().collection("users").doc("ryan").set({
    username: "ryan",
    join_date: "2018-11-13"
  });
  await app.delete();
  console.log("done!");
}

main().catch(err => {
  console.log("ERROR: ", err);
  firebase.apps().forEach(app => app.delete());
});