require 'spec_helper'

describe Immutable::List do
  describe '#take_while' do
    it 'is lazy' do
      -> { Immutable.stream { fail }.take_while { false } }.should_not raise_error
    end

    [
      [[], []],
      [['A'], ['A']],
      [%w[A B C], %w[A B]],
    ].each do |values, expected|
      context "on #{values.inspect}" do
        let(:list) { L[*values] }

        context 'with a block' do
          it "returns #{expected.inspect}" do
            list.take_while { |item| item < 'C' }.should eql(L[*expected])
          end

          it 'preserves the original' do
            list.take_while { |item| item < 'C' }
            list.should eql(L[*values])
          end

          it 'is lazy' do
            count = 0
            list.take_while do |item|
              count += 1
              true
            end
            count.should <= 1
          end
        end

        context 'without a block' do
          it 'returns an Enumerator' do
            list.take_while.class.should be(Enumerator)
            list.take_while.each { |item| item < 'C' }.should eql(L[*expected])
          end
        end
      end
    end
  end
end