require 'spec_helper'

describe Immutable::Vector do
  describe '#fetch' do
    let(:vector) { V['a', 'b', 'c'] }

    context 'with no default provided' do
      context 'when the index exists' do
        it 'returns the value at the index' do
          vector.fetch(0).should == 'a'
          vector.fetch(1).should == 'b'
          vector.fetch(2).should == 'c'
        end
      end

      context 'when the key does not exist' do
        it 'raises an IndexError' do
          -> { vector.fetch(3) }.should raise_error(IndexError)
          -> { vector.fetch(-4) }.should raise_error(IndexError)
        end
      end
    end

    context 'with a default value' do
      context 'when the index exists' do
        it 'returns the value at the index' do
          vector.fetch(0, 'default').should == 'a'
          vector.fetch(1, 'default').should == 'b'
          vector.fetch(2, 'default').should == 'c'
        end
      end

      context 'when the index does not exist' do
        it 'returns the default value' do
          vector.fetch(3, 'default').should == 'default'
          vector.fetch(-4, 'default').should == 'default'
        end
      end
    end

    context 'with a default block' do
      context 'when the index exists' do
        it 'returns the value at the index' do
          vector.fetch(0) { 'default'.upcase }.should == 'a'
          vector.fetch(1) { 'default'.upcase }.should == 'b'
          vector.fetch(2) { 'default'.upcase }.should == 'c'
        end
      end

      context 'when the index does not exist' do
        it 'invokes the block with the missing index as parameter' do
          vector.fetch(3) { |index| index.should == 3}
          vector.fetch(-4) { |index| index.should == -4 }
          vector.fetch(3) { 'default'.upcase }.should == 'DEFAULT'
          vector.fetch(-4) { 'default'.upcase }.should == 'DEFAULT'
        end
      end
    end

    it 'gives precedence to default block over default argument if passed both' do
      vector.fetch(3, 'one') { 'two' }.should == 'two'
    end
  end
end