[ Strategy Pattern / Factory Pattern / MiniTest ] - Example strategy + factory use, with light minitest integration

factory-strategy.rb

require 'minitest/autorun'
require 'minitest/pride'

class ListStrategy
  attr_reader :dates, :foods

  def initialize list
    foods  = list.map { |item| item.keys.map(&:to_s) }
    @dates = list.map { |item| item.fetch(:date) }
    @foods = foods.flatten.uniq - ['date']
  end

end

class HashStrategy
  attr_reader :dates, :foods

  def initialize hash
    @dates = hash.fetch(:dates)
    @foods = hash.fetch(:foods)
  end

end

class SnapshotFactory
  attr_reader :strategy
  def initialize strategy, *raw_input
    @strategy = strategy.new(*raw_input)
  end
  def create
    Snapshot.build do |snapshot|
      snapshot.add_dates *strategy.dates
      snapshot.add_foods *strategy.foods
    end
  end
  def self.create strategy, *raw_input
    new(strategy, *raw_input).create
  end
end

class Snapshot
  attr_reader :dates, :foods
  def initialize
    @dates = []
    @foods = []
  end
  def add_dates *list
    @dates = (dates + list).uniq.sort
  end
  def add_foods *list
    @foods = (foods + list).uniq.sort
  end
  def == other
    dates == other.dates && foods == other.foods
  end

  def self.build
    snapshot = new
    yield snapshot
    snapshot
  end
end

describe "SnapshotFactory" do
  let(:dates) { [ 12341512515, 15082501285 ] }
  let(:foods) { [ 'burrito', 'papaya' ] }
  let(:hash) { { dates: dates, foods: foods } }
  let(:list) do
    [
      { date: 12341512515, burrito: true },
      { date: 15082501285, papaya: true }
    ]
  end

  let(:example_snapshot) do
    Snapshot.build do |snapshot|
      snapshot.add_dates *dates
      snapshot.add_foods *foods
    end
  end

  describe 'List input & Strategy' do
    let(:snapshot) { SnapshotFactory.create(ListStrategy, list) }
    subject { snapshot }
    it { subject.must_equal example_snapshot }
  end

  describe 'Hash input & Strategy' do
    let(:snapshot) { SnapshotFactory.create(HashStrategy, hash) }
    subject { snapshot }
    it { subject.must_equal example_snapshot }
  end

end