mock-google-cloud-pubsub

The goal of this project is to create an in memory emulator for Google Cloud Pub/Sub so this module can be used interchangeably with @google-cloud/pubsub in integration tests for faster test execution.

As an alternative to this package, you could also use a pubsub emulator docker image (eg https://github.com/marcelcorso/gcloud-pubsub-emulator). This package is recomended if the emulator is still not fast enough for you.

Feature set

Only parts of the official API (https://googleapis.dev/nodejs/pubsub/latest/PubSub.html) are covered with this package. A simple example like the one below would work, but you will have to check if more complicated use cases are covered or not.

const { PubSub } = require('mock-google-cloud-pubsub')
const pubsub = new PubSub({})

const [topic] = await pubsub.createTopic(topicName)
const [subscription] = await topic.createSubscription(subscriptionName)
subscription.on('message', message => {
  console.log('Received message:', message.data.toString())
})
topic.publish(Buffer.from('Test message!'))

Pull request for covering more features are welcome, just make sure to write tests for them.

Usage

Intead of using the real thing, simply use the mocked pubsub package whenever you are in integration test.

const { PubSub } = require('@google-cloud/pubsub')
const { PubSub: MockPubSub } = require('mock-google-cloud-pubsub')

const pubsub = process.env.NODE_ENV !== 'test' ? new PubSub({ ... }) : new MockPubSub()

Changelog

• from version 2.0.0 the initializeMocker method was removed, now subscriptions and topics can be created with the regular api methods.

Local dev

Tests cases are run both for an actual and the mocked version, to ensure they work the same way.

To setup connection for real pubsub

• create a confidential.env file in root
• set GCP_PROJECT_ID=<your-project-id>
• set GCP_CREDENTIALS=<credentials for a service account as json>
• set RESOURCE_PREFIX to a uniq string, resources created during tests will be prefix with this value

You can use the docker pubsub emulator instead of the real pubsub:

• run docker-compose up -d
• in confidential.env set GCP_PROJECT_ID=mock-gcp-project and PUBSUB_EMULATOR_HOST=localhost:8685

Run tests with npm t or npm run test:watch for watch mode.