Run with docker

We use Docker in our development and production environments. So we'd like you to use it here. If you absolutely cannot get Docker running, then you can complete the challenge outside of a container, but it's not prefered.

You can read about getting started with Docker Compose Here

Run a "test" container with: docker-compose -f docker-compose.test.yml run sut bash

Once inside of it, run bundle exec rake test to run the test suite.

Challenge

With this challenge, we're testing your ability to

• work with Docker and ruby
• write production code with style
• write tests
• understanding a problem

Overview

We'll be implementing a simplified version of our money distribution system.

A right holder (ie. a client) signs an agreement with RightsUp to collect rights on his behalve. RightsUp will take 20% commission on the revenues.

Therefore, if we receive 100€ for a given recording that is owned by this client, we should keep 20€ to RightsUp and give back 80€ to the right holder.

That's the case if the right holder owns 100% of the right on this recording, but it could also have licensed his rights with somebody else, or the recording may be the result of a co-production with multiple master owners. Lets say for example that a recording's rights is shared between two of our clients, lets say 50/50, each client should receive 40€ and RightsUp should get 10€ twice.

So we can see this problem as having a list of agreement associated to a recording, simplified with the following value objects:

recording_aggreements = [
  LicenseAgreement.new(
    right_holder_slug: 'stillvortalent',
    owned_percentage: 0.50,
    rightsup_commission: 0.20
  ),
  LicenseAgreement.new(
    right_holder_slug: 'suol',
    owned_percentage: 0.50,
    rightsup_commission: 0.20
  )
]

And a row containing revenues for that recording coming from a country.

# a CSV line containing some details about the revenues
# that we associated with one of our recording.
DistributionRow.new(amount: 100, recording_id: 12345, ...)

Part 1 - distribute revenues

There are three tests with different level of complexity. The first one in test/services/compute_distribution/test_simple_case should be trivial to solve.

Inside test/services/compute_distribution/test_split.rb you have more complex example. The first test is exactly the situation explained above. The second one introduce the notion of "business introducer", where another party has brough to us the deal with the client and get a percentage of our commission. In the example, the "introducer" should get 50% of RightsUp commission.
This example is better explained by distribution_chart.png.

The output of this method should be an array of StatementRow (because from this one row of revenue, we might split into multiple clients). (Context: These statement rows could then be used to compute the Statement of the client and create a boundary between the incomming and outgoing revenues).

Your role is to implement the ComputeDistribution method called distribute_row.

Part 2 - invariants

We would like to be always sure that we don't distribute more than what we're receiving. Can you test and implement such logic ? There is a blank test file for that at test/services/compute_distribution/test_invariant.rb.

Part 3 - improvements / open questions

• From a business concern point of view, what are we missing to have a "production-ready" implementation?
• If we want to connect this service to the rest of our system, what would be the events (event name + payload schema) that this service would emit on the bus ?
• ...