Code Talk - How the Test Lights Work on

Published on Thursday, March 08, 2018

aka The Little Submission That Could

by @talum

Submissions take a long, multi-step journey from learn-co gem to

Step 1: learn-co gem

Collection of open source gems (one parent gem with buncha child gems)

Focus for this talk is learn-test

  • figures out what kind of test strategy to use
  • runs tests
  • turns test results into JSON payload
  • show student human readable results (written to results.json)
  • sends payload to Ironbroker V2
    • user info
    • repo info
    • test success/failure info

Step 2: Ironbroker V2

Message broker app written in Sinatra.

Handles all webhooks from variety of sources

  • FlatironUnitTest
  • FlatironRspec
  • GitHub
  • ScheduleOnce

By “handle”, specifically this means process and publish to topic exchange

  • parse
  • save
  • validate
  • resolve event name
  • resolve ampq topic
  • resolve ampq routing key
  • publish
  • handle bugs
  • publish trackable
  • save (again)

Step 3: RabbitMQ

Message broker over AMQP.

Payload arrives at topic exchange, then routed to specific queue (based on routing key). In this example, the local_build queue.

Step 4: Worker

Messages are peeled off by consumers (powered by Sneakers, a high performance RabbitMQ background processing framework for Ruby, aka “the best RabbitMQ processor for Ruby”).

We have Sneakers-backed workers that subscribe to queues then pull off and process messages.

Passed from worker to services:

LocalBuildWorker (AMQP consumer) => LocalBuildSubmissionHandler => SubmissionHandler

Step 5: Service


  • core service that receives all Submission payloads for processing
  • currently doing too much. high level:
    • records submission and progress
    • publishes activity to activity feed
    • publishes a new payload to Pushstream
      • PushstreamPublisher
      • PushstreamWorker
      • PushstreamGateway

On the backend, user now has credit for this submission (aka progress records have been updated), but front-end light still hasn’t flipped.

Step 6: Frontend Scripts for Pushstream pub sub

Every user on gets a subscription to a channel for their user on Pushstream.

Script sets listener for submission Pushstream events.

On submission event, script checks payload and if passing, flips light green.

DETOUR: Debugging

Question: Did my message make it to RabbitMQ?
Answer: Look at Sneakers log (tail -f log/sneakers.log | grep -v eartbeat)

Question: Did the right worker get called?

  • Can’t binding.pry in a worker
  • Instead puts out message and p the payload (p => puts and inspect)
  • Now that you have the payload, you can open up Rails console and pass it to whatever service you wanna test. Run the service synchronously and binding.pry as much as you want w/i service.

WHAT IF you want to run everything locally for testing/development?

  1. Start up phoeyonce and get Docker container id
  2. Log into container as test user, start bash
  3. Run Ironbroker v2 locally
    • Start localtunnel for that port so you can connect to it from Docker container
  4. Open learn-test gem, modify SERVICE_URL to localtunnel url
  5. Start ironboard locally
  6. Start workers locally



  1. WeWork video about RabbitMQ
  2. learn-co gem