Running unit tests ends with error message "The 'credential' property must be an object which implements the Credential interface" even the GOOGLE_APPLICATION_CREDENTIALS env var is set

[shuneihayakawa]

Version info

firebase-functions-test: 0.2.3 firebase-functions: 3.13.2 firebase-admin: 9.5.0

Test case

• target code
  • this functions is almost same with makeUppercase function introduced in official firebase guide

    
    import { region as functionBuilder } from 'firebase-functions';
    import { initializeApp, credential } from 'firebase-admin';

initializeApp({ credential: credential.applicationDefault(), });

export const makeUppercase = functionBuilder('asia-northeast1') .firestore.document('/messages/{documentId}') .onCreate(async (snapshot) => { const original = snapshot.data().original as string; const uppercase = original.toUpperCase(); await snapshot.ref.set({ uppercase }, { merge: true }); });

- unit test
  - this test checks whether the upper case message is added or not on firestore after cloud function is executed
```typescript
import test from 'firebase-functions-test';
import { firestore } from 'firebase-admin';
import { credential } from 'firebase-admin';

import { makeUppercase } from '../src/index';

const tester = test({
  credential: credential.applicationDefault(),
});

it('Tests the sample makeUppercase function', async (done) => {
  const db = firestore();

  const path = 'messages/data1';

  const original = 'original';
  const uppercase = original.toUpperCase();

  afterEach(async () => {
    tester.cleanup();
    await db.doc(path).delete();
  });

  const wrapped = tester.wrap(makeUppercase);
  const snapshot = tester.firestore.makeDocumentSnapshot(
    {
      original,
    },
    path
  );

  db.doc(path).onSnapshot(
    (snapshot) => {
      const data = snapshot.data();
      const result = data?.uppercase;
      if (result == undefined) {
        return;
      }
      expect(result).toEqual(uppercase);
    },
    (error) => {
      done(error);
    }
  );
  await wrapped(snapshot);
});

Steps to reproduce

Clone this repo and follow these steps

• create the new firebase project and get the service account key by following this guide
• store the service account key to functions/service-account-key.json
• prepare docker container

  docker build .
  docker run -it --mount type=bind,src=$PWD,dst=/app YOUR_IMAGE_ID

• install dependencies

  yarn install

• run unit test

  yarn test

  Expected behavior

• firebase-functions-test is able to read the credential from credential.applicationDefault()

Actual behavior

• Unit test ends with error message below

  Invalid Firebase app options passed as the first argument to initializeApp() for the app named "firebase-functions-test". The "credential" property must be an object which implements the Credential interface.

[louis030195]

Same issue, only happen when trying to use makeDocumentSnapshot yet

[Yoshihide-Nishimoto]

Same here

[inlined]

On one hand, I think I see a bug, but on the other, this code sample doesn't follow the SDK's instructions. If you're going to use a credentials file, you should pass that value as the second parameter to initialize your tests:

const tester = test({}, process.env.GOOGLE_APPLICATION_CREDENTIALS);