require 'spec_helper'

describe Immutable::Vector do
  describe '#drop' do
    [
      [[], 10, []],
      [['A'], 10, []],
      [['A'], 1, []],
      [['A'], 0, ['A']],
      [%w[A B C], 0, %w[A B C]],
      [%w[A B C], 2, ['C']],
      [(1..32), 3, (4..32)],
      [(1..33), 32, [33]]
    ].each do |values, number, expected|
      describe "#{number} from #{values.inspect}" do
        let(:vector) { V[*values] }

        it 'preserves the original' do
          vector.drop(number)
          vector.should eql(V[*values])
        end

        it "returns #{expected.inspect}" do
          vector.drop(number).should eql(V[*expected])
        end
      end
    end

    it 'raises an ArgumentError if number of elements specified is negative' do
      -> { V[1, 2, 3].drop(-1) }.should raise_error(ArgumentError)
      -> { V[1, 2, 3].drop(-3) }.should raise_error(ArgumentError)
    end

    context 'when number of elements specified is zero' do
      let(:vector) { V[1, 2, 3, 4, 5, 6] }
      it 'returns self' do
        vector.drop(0).should be(vector)
      end
    end
  end
end