Exercise solve for ruby beginners

combine_anagrams.rb

# encoding: UTF-8
# Exercise description: http://goo.gl/2XsKhW
require 'minitest'
require "minitest/autorun"

############### Exercise 3  ##############
class Array
	def combine_anagrams
		self.group_by{|el| el.downcase.chars.sort}.values
	end
end
describe Array do
  describe "For Array#combine_anagrams" do
  	it "should have instance method combine_anagrams for Array class" do
  		[].methods.select{|i| i.to_s == "combine_anagrams"}.empty?.must_equal false
  	end
	  it "I should to see permutation for a word in words array" do
	  	lst = ['cars', 'for', 'potatoes', 'racs', 'four','scar', 'creams', 'scream']	
	 		lst.combine_anagrams.must_equal([["cars", "racs", "scar"], ["for"], ["potatoes"], ["four"], ["creams", "scream"]])
	  end 
  end
end

dessert.rb

# encoding: UTF-8
# Exercise description: http://goo.gl/2XsKhW
require 'minitest'
require "minitest/autorun"

###### Exercise 4  ##############
class Dessert
	attr_accessor :name, :calories
	def initialize(name, calories)
		self.name = name
		self.calories = calories
	end
	def healthy?
		self.calories < 200
	end
	def delicious?
		true
	end
end
class JellyBean < Dessert
	attr_accessor :name, :calories, :flavor
	def initialize(name, calories, flavor)
		self.name = name
		self.calories =calories
		self.flavor = flavor
	end
	def delicious?
		self.flavor != "black licorice"
	end
end

#test4
describe Dessert do
	before{
		@gelatina = Dessert.new("gelatina", 100)
		@pudim = Dessert.new("Pudim", 300)
		@jujuba = JellyBean.new('jujuba', 250, "black licorice")
	}
	describe "Dessert class" do
		it "healthy? should to respond false for many calories (til 200kal)" do
			@gelatina.healthy?.must_equal true
			@pudim.healthy?.must_equal false
		end
	end
	describe "JellyBean class" do
		it "flavor should to respond FALSE for 'black licorice' taste" do
			@jujuba.delicious?.must_equal false
			@jujuba.flavor = "coco"
			@jujuba.delicious?.must_equal true
		end
	end	
end

jankenpo.rb

# encoding: UTF-8
# Exercise description: http://goo.gl/2XsKhW
require 'minitest'
require "minitest/autorun"

######### exercise 2  ##############
module JanKenPo
	class WrongNumberOfPlayerError < StandardError; end
	class NoSuchStrangyError < StandardError; end
	#PE : Pedra
	#PA: Papel
	#TE: Tesoura
	RN = [["PE,TE", :first], ["TE,PE", :last],["PA,PE", :first],["PE,PA", :last],["TE,PA", :first],["PA,TE", :last]]
	VALIDS_GAMES = ["PE","PA","TE"]
	def self.play(arr_players_and_game)
		raise WrongNumberOfPlayerError unless arr_players_and_game.size==2
		# It's need two parameters for first player
		raise WrongNumberOfPlayerError unless arr_players_and_game.first.size==2
		# It's need two parameters for second player
		raise WrongNumberOfPlayerError unless arr_players_and_game.last.size==2
		raise NoSuchStrangyError unless arr_players_and_game.map{|i| i.last.upcase}.detect{|i| !VALIDS_GAMES.include?(i) }.nil?

		result_method = RN.detect{|i| i.first == arr_players_and_game.map{|i| i.last.upcase}.join(',')}.last
		arr_players_and_game.send result_method
	end
end

### Teste2
describe JanKenPo do
	before{
		@players1 = [["Armando", "PA"], ["Justen", "te"]] # TE > PA
		@players2 = [["Armando", "PE"], ["Justen", "TE"]] # PE > TE
		@players3 = [["Armando", "Pa"], ["Justen", "Pe"]] # PA > PE
	}
	describe "just a game" do
		it "Tesoura winns Papel" do
			JanKenPo.play(@players1).must_equal ["Justen", "te"]
		end
		it "Pedra winns Tesoura" do
			JanKenPo.play(@players2).must_equal ["Armando", "PE"]
		end
		it "Papel winns Pedra" do
			JanKenPo.play(@players3).must_equal ["Armando", "Pa"]
		end		
	end
end

string.rb

# encoding: UTF-8
# Exercise description: http://goo.gl/2XsKhW
require 'minitest'
require "minitest/autorun"

############## Exercise 1  ##############
class String
	def palindrome?
		str = self.split(/\W+/).join('')
    str.reverse.downcase == str.downcase
	end
	def count_words
    lst = self.split(/\W+/).map(&:downcase)
    lst.inject({}){|ac, i| ac.merge!({i.downcase=>lst.count(i)}); ac} 
	end
end

describe String do
	describe "about String's overwrite" do
		it "should to respond positively for instance methods" do
			'teste'.methods.select{|i| i.to_s == "count_words"}.empty?.must_equal false
			'teste'.methods.select{|i| i.to_s == "palindrome?"}.empty?.must_equal false
		end
	end

  describe "when check if string's palindrome" do
    it "should to respond positively for 'amor a --  roma'" do
    	'amor a --  roma'.palindrome?.must_equal true
    end
    it "should to respond positively for upper and lower case like: 'A man, a plan, a canal -- Panama'" do
    	'A man, a plan, a canal -- Panama'.palindrome?.must_equal true
    end    
    it "should to respond negatively for: 'abracadabra'" do
    	'abracadabra'.palindrome?.must_equal false
    end
  end

  describe "when I confere words'number in a phrase and return a hash" do
    it "should to respond for: 'amor a roma'" do
    	'amor a roma roma'.count_words.must_equal({'amor'=>1, 'a'=>1, 'roma'=>2})
    end
    it "should to respond for: 'A man, a plan, a canal -- Panama'" do    	
    	'A man, a plan, a canal -- Panama'.count_words.sort.must_equal({'a'=>3, 'man'=>1, 'canal'=>1, 'panama'=>1, 'plan'=>1}.sort)
    end
  end
end