require 'spec_helper'

describe Immutable::Hash do
  describe '#fetch' do
    context 'with no default provided' do
      context 'when the key exists' do
        it 'returns the value associated with the key' do
          H['A' => 'aye'].fetch('A').should == 'aye'
        end
      end

      context 'when the key does not exist' do
        it 'raises a KeyError' do
          -> { H['A' => 'aye'].fetch('B') }.should raise_error(KeyError)
        end
      end
    end

    context 'with a default value' do
      context 'when the key exists' do
        it 'returns the value associated with the key' do
          H['A' => 'aye'].fetch('A', 'default').should == 'aye'
        end
      end

      context 'when the key does not exist' do
        it 'returns the default value' do
          H['A' => 'aye'].fetch('B', 'default').should == 'default'
        end
      end
    end

    context 'with a default block' do
      context 'when the key exists' do
        it 'returns the value associated with the key' do
          H['A' => 'aye'].fetch('A') { 'default'.upcase }.should == 'aye'
        end
      end

      context 'when the key does not exist' do
        it 'invokes the default block with the missing key as paramter' do
          H['A' => 'aye'].fetch('B') { |key| key.should == 'B' }
          H['A' => 'aye'].fetch('B') { 'default'.upcase }.should == 'DEFAULT'
        end
      end
    end

    it 'gives precedence to default block over default argument if passed both' do
      H['A' => 'aye'].fetch('B', 'one') { 'two' }.should == 'two'
    end

    it 'raises an ArgumentError when not passed one or 2 arguments' do
      -> { H.empty.fetch }.should raise_error(ArgumentError)
      -> { H.empty.fetch(1, 2, 3) }.should raise_error(ArgumentError)
    end
  end
end