Simple decorator example

simple_decorator.rb

require 'delegate'

class SimpleDecorator < SimpleDelegator
  attr_reader :context

  def initialize(raw, view_context = nil)
    @context = view_context if view_context
    super raw
  end

  def self.wrap(collection, view_context = nil)
    collection.map do |obj|
      new obj, view_context
    end
  end
end

simple_decorator_spec.rb

require 'lite_helper'
require 'delegate'
require_relative '../../app/decorators/simple_decorator'

describe SimpleDecorator do
  class TestDecorator < SimpleDecorator
    def test_context_method
      context.helper_method
    end
  end

  let(:context) do
    double('view context').tap do |c|
      allow(c).to receive(:helper_method)
    end
  end

  describe 'decorating collections' do
    it 'decorates collections via .wrap' do
      arr = [1, 2]

      wrapped_array = TestDecorator.wrap(arr)

      wrapped_array.each do |item|
        expect(item).to be_a(SimpleDecorator)
      end
    end

    it 'injects an optional context' do
      arr = [1, 2]

      wrapped_array = TestDecorator.wrap(arr, context)
      wrapped_array.each{|item| item.test_context_method }

      expect(context).to have_received(:helper_method).twice
    end
  end

  context 'when given a view context' do

    it 'can be initialised with a view context' do
      raw = double('raw object')

      wrapped = TestDecorator.new(raw, context)
      wrapped.test_context_method

      expect(context).to have_received(:helper_method)
    end
  end
end