TDD Cards in 55 Using MiniTest

cards.md

Step by Step - Intro to TDD using a deck of playing cards

1. Create and edit a file called cards.rb

2. 👇

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

3. ruby -I"." cards.rb

4. 👇

describe Deck do
end

5. ruby -I"." cards.rb

6. 👇

class Deck
end

7. ruby -I"." cards.rb

8. 👇

describe Deck do
  it "has a to_a method" do
    Deck.new.respond_to?(:to_a).must_equal true
  end
  ...

9. ruby -I"." cards.rb

10. 👇

class Deck
  def to_a
  end
  ...

11. ruby -I"." cards.rb

12. 👇

describe Deck do
  describe "#to_a" do
    it "has 52 items" do
      Deck.new.to_a.count.must_equal 52
    end
    ...

13. ruby -I"." cards.rb

14. 👇

class Deck
  def to_a
    52.times.map { 0 }
  end
  ...

15. ruby -I"." cards.rb

16. 👇

describe Deck do
  describe "#to_a" do
    it "contains Cards" do
      Deck.new.to_a[0].class.must_equal Card
    end
    ...

17. ruby -I"." cards.rb

18. 👇

class Card
end

19. 👇

class Deck
  def to_a
    52.times.map { Card.new }
  end
  ...

20. ruby -I"." cards.rb

21. 👇

describe Card do
  it "has a rank" do
    Card.new.respond_to?(:rank).must_equal true
  end
  ...

22. ruby -I"." cards.rb

23. 👇

class Card < Struct.new(:rank)
end

24. ruby -I"." cards.rb

25. 👇

describe Card do
  it "has a suit" do
    Card.new.respond_to?(:suit).must_equal true
  end
  ...

26. ruby -I"." cards.rb

27. 👇

class Card < Struct.new(:rank, :suit)
end

28. ruby -I"." cards.rb

29. 👇

describe Deck do
  it "has 13 ranks" do
    Deck::RANKS.count.must_equal 13
  end
  ...

30. ruby -I"." cards.rb

31. 👇

class Deck
  RANKS = %i[ace two three four five sex seven eight nine ten jack queen king]
  ...

32. ruby -I"." cards.rb

33. 👇

describe Deck do
  it "has 4 suits" do
    Deck::SUITS.count.must_equal 4
  end
  ...

34. ruby -I"." cards.rb

35. 👇

class Deck
  SUITS = %i[clubs diamonds spades hearts]
  ...

36. ruby -I"." cards.rb

37. 👇

describe Deck do
  it "must have at least 4 queens" do
    Deck.new.to_a.select {|card| card.rank == :queen }.count.must_be :>= 4
  end
  ...

38. ruby -I"." cards.rb

39. 👇

class Deck
  ...
  def to_a
    RANKS.map {|rank| Card.new(rank) }
  end
  ...

40. ruby -I"." cards.rb

41. 👇

class Deck
  ...
  def to_a
    RANKS.map {|rank| SUITS.map {|suit| Card.new(rank) } }
  end
  ...

42. ruby -I"." cards.rb

43. 👇

class Deck
  def to_a
    RANKS.flat_map {|rank| SUITS.map {|suit| Card.new(rank) } }
  end
  ...

44. ruby -I"." cards.rb

45. 👇

describe Card do
  it "#to_s is the rank and suit in enligsh" do
    Card.new(:ace, :hearts).to_s.must_equal "ace of hearts"
  end
  ...

46. ruby -I"." cards.rb

47. 👇

class Card
  def to_s
    "#{rank} of #{suit}"
  end
  ...

48. ruby -I"." cards.rb

49. 👇

describe Deck do
  it "initializes with a shoe size" do
    Deck.new(2).shoe_size.must_equal 2
  end

50. ruby -I"." cards.rb

51. 👇

class Deck
  ...
  def initialize(shoe_size=1)
    @shoe_size = shoe_size
  end

  attr_reader :shoe_size
  ...
    ~~~

52) ruby -I"." cards.rb

53) :point_down:
~~~ruby
describe Deck do
  describe "#to_a" do
    it "has 104 items with a shoe_size of 2" do
      Deck.new(2).to_a.count.must_equal 52
    end
    ...

54. ruby -I"." cards.rb

55. DONE!