$: << '../lib'

require 'geo_graf'

describe GeoGraf do
  describe "#intersections_for" do
    subject(:intersections_for_input) { described_class.intersections_for(input) }
    
    let(:calculator) { double('Calculator') }
    let(:input) { double('Input') }
    let(:intersection_calculator_output) { double('Output') }

    before do
      allow(GeoGraf::IntersectionCalculator).to receive(:new).with(input).and_return(calculator)
      allow(calculator).to receive(:intersections).and_return(intersection_calculator_output)
    end

    it "runs intersections on a new instance of IntersectionCalculator" do
      expect(intersections_for_input).to eq(intersection_calculator_output)
    end
  end
end