require 'spec_helper'

describe Immutable::Deque do
  describe '#push' do
    [
      [[], 'A', ['A']],
      [['A'], 'B', %w[A B]],
      [%w[A B C], 'D', %w[A B C D]],
    ].each do |original, item, expected|
      context "pushing #{item.inspect} into #{original.inspect}" do
        let(:deque) { D.new(original) }

        it 'preserves the original' do
          deque.push(item)
          deque.should eql(D.new(original))
        end

        it "returns #{expected.inspect}" do
          deque.push(item).should eql(D.new(expected))
        end

        it 'returns a frozen instance' do
          deque.push(item).should be_frozen
        end
      end
    end

    context 'on a subclass' do
      let(:subclass) { Class.new(Immutable::Deque) }
      let(:empty_instance) { subclass.new }
      it 'returns an object of same class' do
        empty_instance.push(1).class.should be subclass
      end
    end
  end
end