require 'spec_helper' describe Calculator::PerItem do let(:calculator) { Calculator::PerItem.new(preferred_amount: 10) } let(:shipping_calculable) { double(:calculable) } let(:line_item) { build(:line_item, quantity: 5) } it "correctly calculates on a single line item object" do allow(calculator).to receive_messages(calculable: shipping_calculable) expect(calculator.compute(line_item).to_f).to eq(50) # 5 x 10 end context "extends LocalizedNumber" do it_behaves_like "a model using the LocalizedNumber module", [:preferred_amount] end end