Firestore emulator does not support transactional queries

[REQUIRED] Environment info

7.2.2

firebase-tools: 7.2.2

Platform: macOS 10.14.5

[REQUIRED] Test case

export const myFunction = functions.https.onCall(
    async (data: any, context: CallableContext): Promise<void> => {
        const db = admin.firestore();
        const my_collection: CollectionReference = db.collection(`test_collection`);
        return await db.runTransaction<void>(async (transaction) => {

            const result = await transaction.get(my_collection.doc());
            console.debug(result); // This works

            await transaction.get(my_collection.limit(1));
            // This will crash
        });
});

[REQUIRED] Steps to reproduce

Run firebase emulators:start and call the function from Web App

[REQUIRED] Expected behavior

Emulator should just work as production

[REQUIRED] Actual behavior

Unhandled error Error at Http2CallStream.<anonymous> (/PATH_TO_PROJECT/functions/node_modules/@grpc/grpc-js/build/src/call.js:68:41) at Http2CallStream.emit (events.js:208:15) at /PATH_TO_PROJECT/functions/node_modules/@grpc/grpc-js/build/src/call-stream.js:71:22 at processTicksAndRejections (internal/process/task_queues.js:75:11) { code: 2, details: ‘’, metadata: Metadata { options: undefined, internalRepr: Map { ‘content-type’ => [Array] } } }

[ryanpbrewster]

Totally reasonable. There is a bit of work needed in order to support this without breaking the normal concurrency handling, but it’s very doable. I’ll keep this issue open to track the progress.

[ranmocy]

That is a reasonable concern. If you ask me, I would say for an emulator, firstly it should allow any legitimate client code to run against it, and latter to behave as close to production version as possible. So I think it’s totally reasonable to minimize the support on concurrency cases.

That being said, would it be possible to have some simple implementation without support of concurrency first? That would allow us to write test for our Firebase functions which rely on Firestore heavily, where mocking Firestore doesn’t make a lot sense.

Thanks!