require 'spec_helper'

describe Immutable::Hash do
  let(:hash) { H.new('A' => 'aye', 'B' => 'bee', 'C' => 'see', nil => 'NIL') }

  describe '#slice' do
    let(:slice) { hash.slice(*values) }

    context 'with all keys present in the Hash' do
      let(:values) { ['B', nil] }

      it 'returns the sliced values' do
        expect(slice).to eq(described_class.new('B' => 'bee', nil => 'NIL'))
      end

      it "doesn't modify the original Hash" do
        slice
        hash.should eql(H.new('A' => 'aye', 'B' => 'bee', 'C' => 'see', nil => 'NIL'))
      end
    end

    context "with keys aren't present in the Hash" do
      let(:values) { ['B', 'A', 3] }

      it 'returns the sliced values of the matching keys' do
        expect(slice).to eq(described_class.new('A' => 'aye', 'B' => 'bee'))
      end

      it "doesn't modify the original Hash" do
        slice
        hash.should eql(H.new('A' => 'aye', 'B' => 'bee', 'C' => 'see', nil => 'NIL'))
      end
    end

    context 'on a Hash with a default block' do
      let(:hash) { H.new('A' => 'aye', 'B' => 'bee') { 'nothing' }}
      let(:values) { ['B', nil] }

      it 'maintains the default block' do
        expect(slice['C']).to eq('nothing')
      end
    end
  end
end