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Gen2 / TypeScript: Snapshot from 'makeDocumentSnapshot' Doesn't Work for 'onDocumentCreated' #205
Description
Version info
firebase-functions-test: 3.1.0
firebase-functions: 4.4.1
firebase-admin: 11.9.0
Test case
Firebase Cloud Function
import { onDocumentCreated } from 'firebase-functions/v2/firestore';
import * as logger from 'firebase-functions/logger';
import { initializeApp } from 'firebase-admin/app';
initializeApp();
export const docCreateTest = onDocumentCreated(
'messages/{documentId}',
(event) => {
const original = event.data?.data().original;
logger.log('Uppercasing: ', original);
const uppercase = original.toUpperCase();
return event.data.ref.set({ uppercase }, { merge: true });
}
);Unit Test
Note: Using Vitest but I believe it would be the same result with Jest, etc.
import { describe, test, expect } from 'vitest';
import firebaseFunctionsTest from 'firebase-functions-test';
import * as admin from 'firebase-admin';
import { docCreateTest } from '../functions/index';
// NOTE: Don't need the service account file when using
// GOOGLE_APPLICATION_CREDENTIALS environment variable
const { wrap, firestore } = firebaseFunctionsTest({
databaseURL: 'http://127.0.0.1:8080',
projectId: 'project-id-test',
});
describe('Running tests...', () => {
test('should return uppercase message', async () => {
// create mock doc snapshot
const snap = firestore.makeDocumentSnapshot(
{ original: 'hello' },
'messages/abc'
);
// TODO: Workaround for https://github.com/firebase/firebase-functions-test/issues/163
// @ts-ignore
const wrapped = wrap(docCreateTest);
await wrapped(snap);
const result = await admin.firestore().doc('messages/abc').get();
expect(result.data()?.uppercase).toBe('HELLO');
});
});Steps to reproduce
Run the unit test against the Firebase function and it will result in a Cannot read properties of undefined (reading 'original') when trying to create the 'original' variable in the function (const original = event.data?.data().original;).
This is because event.data.data() is undefined.
Expected behavior
The document snapshot created in the unit test with makeDocumentSnapshot is in the correct format to be passed into onDocumentCreated so that its data can be read.
Actual behavior
The 'original' variable cannot be created in the Firebase function because it can't read the data object in the passed in event resulting in the following error...
Cannot read properties of undefined (reading 'original')
I guess this is due to makeDocumentSnapshot creating a DocumentSnapshot and the event in onDocumentCreated expected to have a type of FirestoreEvent<QueryDocumentSnapshot | undefined, { documentId: string; }>.
I can't find any alternative to makeDocumentSnapshot that should be used in this scenario for gen2 functions though so I'm guessing this isn't supported yet?
If I create an object that contains the document snapshot as the value of a data parameter, it will work
test('should return uppercase message', async () => {
// create mock doc snap
const snap = firestore.makeDocumentSnapshot(
{ original: 'hello' },
'messages/abc'
);
// TODO: My workaround for missing 'data' property when passing event
const event = { data: snap }; // <-- CREATING THE NEW OBJECT
// eslint-disable-next-line @typescript-eslint/ban-ts-comment
// @ts-ignore
const wrapped = wrap(docCreateTest);
await wrapped(event); // <-- PASSING THE OBJECT I CREATED INSTEAD OF 'snap'
const result = await admin.firestore().doc('messages/abc').get();
expect(result.data()?.uppercase).toBe('HELLO');
});I'm not sure how much of this library is currently expected to work with the gen2 Firebase functions, but I couldn't find this issue already logged and the gen2 samples don't cover onDocumentCreated functions.
Cheers
Jess
Activity
greg-md commentedon Dec 14, 2023
The same issue happens with
onDocumentWritten. Theevent.data.before.data()is retuning a strange object.And in the v2
onDocumentWrittentheevent.data.before.data()returns:I also catched that
event.before.data()returns the valid data, but it throws a typescript error.The
eventobject in console logs looks strange:greg-md commentedon Dec 14, 2023
@JessRascal seems like v2 wrapped function expects a cloud event, not a change/snapshot object. So if you wrap your input into a cloud event object type, it works. See: https://github.com/firebase/firebase-functions-test/blob/master/src/cloudevent/mocks/firestore/helpers.ts#L68
wmurphyrd commentedon Apr 5, 2024
Would be nice if they updated the docs to reflect this
https://firebase.google.com/docs/functions/unit-testing#constructing_test_data
brandones commentedon Oct 15, 2024
The docs have still not been updated
CorieW commentedon May 28, 2026
Hey @JessRascal. I understand this to be a docs issue. I'll see about getting the docs updated.