Firebase Auth emulator "ECONNREFUSED" in CI

The test suite tried to reach the Firebase Auth emulator on 127.0.0.1:9099 but the connection was refused. The emulator was not yet listening, or it bound a different host or port.

What this error means

Auth tests fail with "Error: connect ECONNREFUSED 127.0.0.1:9099". The emulator was started but tests ran before it was ready, or the configured port does not match.

Firebase emulator

Error: connect ECONNREFUSED 127.0.0.1:9099
    at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1595:16)

Common causes

Tests ran before the emulator was ready

The emulator takes a moment to bind its port; tests started too early get connection refused.

A port or host mismatch

The emulator bound a different port than the env expects, so the client connects nowhere.

How to fix it

Run tests via emulators:exec

Wrap the test command in firebase emulators:exec so it waits for readiness.
Set the emulator host env to match the started port.
Do not launch tests in parallel with the emulator start.

Terminal

firebase emulators:exec --only auth "npm test"

Match the configured emulator port

Align firebase.json emulator ports with FIREBASE_AUTH_EMULATOR_HOST so the client hits the right port.

How to prevent it

Use emulators:exec so tests wait for the emulator.
Keep firebase.json ports and the host env in sync.
Avoid racing test start against emulator start.