module Concurrent
  module Concern

    RSpec.describe Observable do

      let (:described_class) do
        Class.new do
          include Observable
          public :observers, :observers=
        end
      end

      let(:observer_set) { double(:observer_set) }
      subject { described_class.new }

      before(:each) do
        subject.observers = observer_set
      end

      it 'does not initialize set by by default' do
        expect(described_class.new.observers).to be_nil
      end

      it 'uses the given observer set' do
        expected          = Collection::CopyOnWriteObserverSet.new
        subject.observers = expected
        expect(subject.observers).to eql expected
      end

      it 'delegates #add_observer' do
        expect(observer_set).to receive(:add_observer).with(:observer, :update) { |v| v }
        expect(subject.add_observer(:observer)).to eq :observer
      end

      it 'delegates #with_observer' do
        expect(observer_set).to receive(:add_observer).with(:observer, :update) { |v| v }
        expect(subject.with_observer(:observer)).to eq subject
      end

      it 'delegates #delete_observer' do
        expect(observer_set).to receive(:delete_observer).with(:observer)
        subject.delete_observer(:observer)
      end

      it 'delegates #delete_observers' do
        expect(observer_set).to receive(:delete_observers).with(no_args)
        subject.delete_observers
      end

      it 'delegates #count_observers' do
        expect(observer_set).to receive(:count_observers).with(no_args)
        subject.count_observers
      end
    end
  end
end