amqp-event-tester

An AMQP topic exchange event listener that can be configured to listen for your event emitter's events and, optionally, return a configurable test result. Use this for integration testing of your event emitters.

Why?

When running integration tests of code that emits persistent messages to an AMQP message queue via a topic exchange, you don't want to leave messages in the queue, as that will cause confusion the next time you run your tests. Instead you need to be able to pull those messages from the queue.

A typical workflow often involves emitting a message designed to be consumed by another service, which will then emit a response message when it's done what it needs to do. To properly integration-test the entire round-trip it's desirable to have a mock service that emits a response message that your service listens for.

Limitations of this tester.

I've built this to test some specific microservices I am working on, and so appreciate it's not useful for a range of other scenarios, such as direct or fanout exchanges, or services that look for a replyTo header to use to emit response messages to.

If you need this kind of flexibility feel free to fork this repo and contribute a PR. See the contributing notes for details.

Docker Image

• davesag/amqp-event-tester

Configuration

Set the following environment variables

Variable	Default	Notes
NODE_ENV	development	Change this to test if using this to run against integration tests.
AMQP_URL	amqp://127.0.0.1	The url of the AMQP message queue to use.
EXCHANGE	amqp-test	The name of the exchange.
EVENTS	none	Base64 encoded JSON object describing the events to listen for and, optionally, the responses to emit.

Configuring events

Supply an environment variable as follows

EVENTS=xxx

Where xxx is a Base64 encoded JSON in the form:

{
  [eventKey]: {
    queue: 'queue to listen to',
    response: 'event to respond with',
    data: { some: 'data to respond with' }
  },
  ...
}

Example

EVENTS=eyJyZWdpc3RlciI6eyJxdWV1ZSI6IlJFR0lTVFJBVElPTiIsInJlc3BvbnNlIjoicmVnaXN0ZXJlZCIsImRhdGEiOnsidXJsIjoiaHR0cDovL2xvY2FsaG9zdDo5MDkwIn19LCJkaXNtaXNzIjp7InF1ZXVlIjoiRElTTUlTU0FMIn19

Decodes to

{
  register: {
    queue: 'REGISTRATION',
    response: 'registered',
    data: {
      url: 'http://localhost:9090'
    }
  },
  dismiss: {
    queue: 'DISMISSAL'
  }
}

This tells the event tester to

• listen for register on queue REGISTRATION and, when it hears it, respond with key registered and data { url: 'http://localhost:9090' }, and
• listen for dismiss on queue DISMISSAL, but do not respond.

Events that do not require a response

If your event does not require any sort of response then you can simply leave out the response and data fields. This will tell the tester to just pull the message from the queue, so you don't end up with a load of stray messages littering your queue.

Development

Branches

Branch	Tests	Code Coverage	Audit	Comments
develop				Latest Staging Release
main				Latest Production Release

Prerequisites

• NodeJS, 8.10.0+ (I use nvm to manage Node versions — brew install nvm.)
• Docker (if on a Mac then use Docker for Mac, not the homebrew version)

Initialisation

npm install

Starting the server

You may add environment variables to a local .env file

npm start

Note: The Dockerised version will run the script start.sh to start the service, as this will wait for RabbitMQ to start. This is important when running this on a CI system.

Test it

• npm test — runs the unit tests (quick)

or run npm run backend to start the essential services, then:

• npm run test:integration — runs the integration tests (not so quick)

Lint it

npm run lint

To auto-fix linting issues.

npm run lint -- --fix

Make the code prettier

This runs on every commit but you can do this manually as well via:

npm run prettier

Contributing

Please see the contributing notes.