cloud function extension emulator throws error when adding data

[russellwheatley]

[REQUIRED] Environment info

firebase-tools:
8.17.0

Platform:
macOS Catalina 10.15.4

[REQUIRED] Test case

See steps to reproduce.

[REQUIRED] Steps to reproduce

1. git clone git@github.com:firebase/extensions.git
2. run npm i from root of extension's directory.
3. cd rtdb-limit-child-nodes directory
4. create test-params.env file. Add environment variables & insert project id as appropriate:

LOCATION=europe-west2
MAX_COUNT=2
NODE_PATH=test
SELECTED_DATABASE_INSTANCE=[INSERT YOUR OWN PROJECT ID]

5. delete line 129: default: ${DATABASE_INSTANCE} & line 131:validationRegex: ^([0-9a-z_.-]*)$ from the extension.yaml file otherwise you will encounter the issue I raised here.
6. run CLI command with your project id : firebase ext:dev:emulators:start --test-params=test-params.env --project=[INSERT YOUR OWN PROJECT ID]

[REQUIRED] Expected behavior

I expect the Cloud Function emulator to run when I add data to the RTDB emulator.

[REQUIRED] Actual behavior

Error is thrown:

@firebase/database: FIREBASE FATAL ERROR: Cannot parse Firebase url. Please use https://<YOUR FIREBASE>.firebaseio.com

[joehan]

Closing - this is fixed by the extensions emulator ((https://firebase.google.com/docs/emulator-suite/use_extensions)