Update to the dependency system to support two types of null substitutes, one where the only public interface is call, and one where it is any method. This allows us to more simply test object boundaries.

broadcaster.rb

module Broadcasters
  class OrderBroadcaster
    include Wisper::Publisher
    include DependencySupport::NullSubstitute
    
    def changed(order)
      // do some stuff
    end
  end
end

inert_callable.rb

 # Basic Inert Class maps args to return values
  class InertCallable

    attr_reader :call_history

    def initialize
      @return = {}
      @call_history = []
    end

    def call(*args)
      @call_history << args
      @return[args]
    end

    def setup(*args, ret)
      @return[args] = ret
    end

    def called_with?(*args)
      @call_history.include? args
    end

    def called_only_with?(*args)
      @call_history == [args]
    end

  end

inert_null_object.rb

  class InertNullObject

    def initialize(parent_klass)
      @methods = {}
      @parent_klass = parent_klass
    end

    def method_missing(m, *args, &block)
      raise NoMethodError, "The parent class #{@parent_klass} does not define a #{m} method" unless @parent_klass.method_defined?(m)

      @methods[m] ||= InertCallable.new
      args.length > 0 ? @methods[m].(*args) : @methods[m]
    end

  end

null_substitute.rb

  module NullSubstitute
    def self.included(base)
      base.extend(ClassMethods)
    end

    module ClassMethods
      def inert
        InertNullObject.new(self)
      end
    end
  end

update_order.rb

module Logistics
  module ArrivalEstimates
    class UpdateOrder < FoodeeService

      dependency :find_estimate, Queries::ArrivalEstimates::FindOrCreateByOrder
      dependency :save_record, Commands::SaveRecord
      dependency :order_broadcaster, Broadcasters::OrderBroadcaster

      def call(order, log)
        estimate = find_estimate.(order.id)
        estimate.update_estimate(log)
        save_record.(order)
        order_broadcaster.changed(order)
      end

    end
  end
end

update_order_test.rb

require 'test_helper'

module Logistics
  module ArrivalEstimates
    class UpdateOrderTest < ActiveSupport::TestCase

      let(:update_order) {Logistics::ArrivalEstimates::UpdateOrder.as_subject}
      let(:log) {Logistics::ArrivalEstimate::EstimateLog.new(timestamp: Time.current, arrival_estimate: Time.current + 1.hours)}
      let(:order) {Order.new(id: 1)}
      let(:estimate) {Logistics::ArrivalEstimate.new(id: 1, order: order)}

      describe 'updating an order delivery estimate' do

        context 'when the order is ready to be picked up' do
          it 'updates the pickup estimate' do
            order.state = 'driver_confirmed'

            # Setup
            update_order.find_estimate.setup(order.id, estimate)
            update_order.save_record.setup(estimate)

            # exercise
            update_order.(order, log)

            # assert
            assert estimate.pickup_estimate == log
            assert update_order.save_record.called_with_only? order
            assert update_order.order_broadcaster.changed.called_only_with? order
          end
        end

        context 'when the order is ready to be delivered' do
          it 'updates the estimate' do
            order.state = 'picked_up'

            # Setup
            update_order.find_estimate.setup(order.id, estimate)
            update_order.save_record.setup(estimate)

            # exercise
            update_order.(order, log)

            # assert
            assert estimate.delivery_estimate == log
            assert update_order.save_record.called_with_only? order
            assert update_order.order_broadcaster.changed.called_only_with? order
          end
        end
      end
    end
  end
end