require 'spec_helper'

describe Immutable::Deque do
  describe '#unshift' do
    [
      [[], 'A', ['A']],
      [['A'], 'B', %w[B A]],
      [['A'], 'A', %w[A A]],
      [%w[A B C], 'D', %w[D A B C]],
    ].each do |values, new_value, expected|
      context "on #{values.inspect} with #{new_value.inspect}" do
        let(:deque) { D[*values] }

        it 'preserves the original' do
          deque.unshift(new_value)
          deque.should eql(D[*values])
        end

        it "returns #{expected.inspect}" do
          deque.unshift(new_value).should eql(D[*expected])
        end


        it 'returns a frozen instance' do
          deque.unshift(new_value).should be_frozen
        end
      end
    end
  end
end