require 'spec_helper'

describe 'Veritas::Optimizer.chain' do
  subject { object.chain(*optimizers) }

  let(:object)          { Optimizer            }
  let(:noop)            { object::Noop         }
  let(:optimizer_class) { Class.new(Optimizer) }
  let(:operation)       { mock('Operation')    }

  context 'with no optimizers' do
    let(:optimizers) { [] }

    it { should equal(noop) }

    it 'returns a block that returns the operation' do
      subject.call(operation).should equal(operation)
    end
  end

  context 'with an optimizer that can optimize the operation' do
    let(:optimizers) { [ optimizer_class ] }
    let(:optimized)  { mock('Optimized')   }

    before do
      optimized = self.optimized
      optimizer_class.send(:define_method, :optimizable?) { true      }
      optimizer_class.send(:define_method, :optimize)     { optimized }
    end

    it { should_not equal(noop) }

    it { should be_kind_of(Proc) }

    it 'returns a block that optimizes the operation' do
      subject.call(operation).should equal(optimized)
    end
  end

  context 'with an optimizer that cannot optimize the operation' do
    let(:optimizers) { [ optimizer_class ] }

    before do
      optimizer_class.send(:define_method, :optimizable?) { false }
    end

    it { should_not equal(noop) }

    it { should be_kind_of(Proc) }

    it 'returns a block that calls the successor (Noop) with the operation' do
      subject.call(operation).should equal(operation)
    end
  end
end