Testing Ruby

Slides for my presentation at HackBulgaria Ruby course - coreruby.github.io

Transcript

1. Testing Ruby
   Radoslav Stankov 04/12/2014
   

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2. Кой съм аз?
   @rstankov
   
   http://rstankov.com
   
   http://github.com/rstankov
   

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4. • 2002 - първия ми “професионален проект” (flash)
   • 2008 - първи PHP unit test
   • 2009 - първи Ruby on Rails проект
   • 2009 - първи Ruby unit test
   • 2010 - официално Ruby developer
   • 2010 - първи selenium acceptance test
   • 2014 - все още пиша главно на Ruby … :P
   

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6. I have a plan!
   

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7. • За какво са ни нужни тестове?
   • Какво е автоматичен тест?
   • Какви видове тестове има?
   • Какво е добър тест?
   • Как да пишем добри тестове?
   • Какво трябва да тестваме?
   • Какво са “Mocks”?
   • Какво е “RSpec”?
   • Какво е “Test Driven Development”?
   • Какво е “Fragile tests”?
   

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8. За какво са ни нужни
   тестове?
   

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16. puts "1 + 1 = #{Calculation.new("1 + 1").value}"
    puts "2 - 1 = #{Calculation.new("2 - 1").value}"
    puts "3 * 2 = #{Calculation.new("3 * 2").value}"
    

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17. class Calculation
    # ...
    def to_s
    "#{expression} = #{value}"
    end
    end
    

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18. puts Calculation.new("1 + 1")
    puts Calculation.new("2 - 1")
    puts Calculation.new("3 * 2")
    

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19. raise "INVALID" unless Calculation.new("1 + 1").value == 2
    raise "INVALID" unless Calculation.new("2 - 1").value == 1
    raise "INVALID" unless Calculation.new("3 * 2").value == 6
    puts 'Everything okay :)'
    

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20. def assert_calculation(expression, expected)
    calculation = Calculation.new(expression)
    if calculation.value != expected
    raise "#{calculation}, but expected #{expected}"
    end
    end
    

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21. assert_calculation '1 + 1', 2
    assert_calculation '2 - 1', 1
    assert_calculation '3 * 2', 6
    puts 'Everything okay :)'
    

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22. • code task 1
    • check task 1

    • code task 2
    • check task 2
    • check task 1

    • code task 3
    • check task 3
    • check task 2
    • check task 1

    • code task 4
    • check task 4
    • check task 3
    • check task 2
    • check task 1
    • code task 1
    • code task 1 test
    • run tests

    • code task 2
    • code task 2 test
    • run tests

    • code task 3
    • code task 3 test
    • run tests

    • code task 4
    • code task 4 test
    • run tests
    Manual Automatic
    

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23. • code task 1
    • check task 1

    • code task 2
    • check task 2
    • check task 1

    • code task 3
    • check task 3
    • check task 2
    • check task 1

    • code task 4
    • check task 4
    • check task 3
    • check task 2
    • check task 1
    • code task 5
    • check task 4
    • check task 4
    • check task 3
    • check task 2
    • code task 1
    • code task 1 test
    • run tests

    • code task 2
    • code task 2 test
    • run tests

    • code task 3
    • code task 3 test
    • run tests

    • code task 4
    • code task 4 test
    • run tests
    • code task 5
    • code task 5 test
    • run tests
    Manual Automatic
    

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24. • Safety net
    • Reduces bugs in new or existing features
    • Forces you to understand the features and
    communication between components
    • Reduces the cost for new features
    • Making code testable decreases complexity and
    modularity
    

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25. Какво е автоматичен
    тест?
    

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26. class CalculationTest < Minitest::Test
    def test_add
    assert_equal 2, Calculation.new('1 + 1').value
    end
    def test_subtract
    assert_equal 1, Calculation.new('2 - 1').value
    end
    def test_multiply
    assert_equal 6, Calculation.new('3 * 2').value
    end
    end
    

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28. class ArrayTest < Minitest::Test
    def setup
    @array = []
    end
    def test_empty
    assert @array.empty?
    end
    def test_push
    @array << 1
    assert_equal [1], @array
    end
    end
    

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29. class ArrayTest < Minitest::Test
    def setup
    @array = []
    end
    def test_empty
    assert @array.empty?
    end
    def test_push
    @array << 1
    assert_equal [1], @array
    end
    end
    Test Suite
    

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30. class ArrayTest < Minitest::Test
    def setup
    @array = []
    end
    def test_empty
    assert @array.empty?
    end
    def test_push
    @array << 1
    assert_equal [1], @array
    end
    end
    

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31. class ArrayTest < Minitest::Test
    def setup
    @array = []
    end
    def test_empty
    assert @array.empty?
    end
    def test_push
    @array << 1
    assert_equal [1], @array
    end
    end
    Test Setup
    

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32. class ArrayTest < Minitest::Test
    def setup
    @array = []
    end
    def test_empty
    assert @array.empty?
    end
    def test_push
    @array << 1
    assert_equal [1], @array
    end
    end
    

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33. class ArrayTest < Minitest::Test
    def setup
    @array = []
    end
    def test_empty
    assert @array.empty?
    end
    def test_push
    @array << 1
    assert_equal [1], @array
    end
    end
    Test Case
    

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34. class ArrayTest < Minitest::Test
    def setup
    @array = []
    end
    def test_empty
    assert @array.empty?
    end
    def test_push
    @array << 1
    assert_equal [1], @array
    end
    end
    

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35. class ArrayTest < Minitest::Test
    def setup
    @array = []
    end
    def test_empty
    assert @array.empty?
    end
    def test_push
    @array << 1
    assert_equal [1], @array
    end
    end
    Assertion
    

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36. class ArrayTest < Minitest::Test
    def setup
    @array = []
    end
    def test_empty
    assert @array.empty?
    end
    def test_push
    @array << 1
    assert_equal [1], @array
    end
    end
    

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37. Kent Beck
    • based on SUnit (Smalltalk)
    • released around 1998
    xUnit
    

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38. Какви видове тестове
    има?
    

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39. System under test (SUT)
    Tests
    Unit test Integration test Acceptance test
    SUD
    

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40. Unit Test Integration Test Acceptance Test
    Tests one object Tests one “component” Tests the whole stack
    Isolated with mocks Some times uses stubs
    Uses the UI

    Expresses domain terms
    Fast Slow Very slow
    Helps for good design Helps for verification Helps for verification
    

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41. Какво е добър тест?
    

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42. “Не трябва да губя енергия за пускане на
    тестове ”
    Лесни за пускане
    

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43. “Пускането на тестове не трябва да ме
    разсейва от проблема, който решавам ”
    Бързи
    

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44. “Не трябва да губя излишна енегрия зада
    разбера даден тест”
    Прости
    

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45. “Трябва да имам чувството, че ако тестовете
    ми минават, значи кода ми работи”
    Надежни
    

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46. “Не трябва да се налага да се пренаписват
    при всяка промяна ”
    Гъвкави
    

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47. “Когато даден тест се счупи, трябва да знам
    точно кой тест се е счупил и защо”
    Локализирани
    

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48. Как да пишем добри
    тестове?
    

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50. 4 Phase testing
    

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51. 4 Phase testing
    Setup
    

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52. 4 Phase testing
    Setup
    Action
    

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53. 4 Phase testing
    Setup
    Action
    Assertion
    

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54. 4 Phase testing
    Setup
    Action
    Assertion
    Teardown
    

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55. 4 Phase testing
    Setup
    Action
    Assertion
    Teardown
    

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56. class OrderTest < Minitest::Test
    def test_proccess
    order = Order.new
    assert_equal Date.today, order.initiated_at.to_date
    assert_nil order.user
    assert order.empty?
    product = Product.new
    order << product
    assert_equal 1, order.size
    assert !order.valid?
    user = User.new
    order.user = user
    assert_equal user, order.user
    assert !order.valid?
    

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57. assert !order.valid?
    user = User.new
    order.user = user
    assert_equal user, order.user
    assert !order.valid?
    def Order.can_be_processed_today?
    true
    end
    assert order.valid?
    order.cancel
    assert_equal :canceled, order.state
    end
    end
    

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58. class OrderTest < Minitest::Test
    def test_proccess
    order = Order.new
    assert_equal Date.today, order.initiated_at.to_date
    assert_nil order.user
    assert order.empty?
    product = Product.new
    order << product
    assert_equal 1, order.size
    assert !order.valid?
    user = User.new
    order.user = user
    assert_equal user, order.user
    assert !order.valid?
    def Order.can_be_processed_today?
    true
    end
    assert order.valid?
    order.cancel
    assert_equal :canceled, order.state
    end
    end
    

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62. class OrderTest < Minitest::Test
    def setup
    @order = Order.new
    end
    def around(&block)
    Order.stub :can_be_processed_today?, true, &block
    end
    def test_initiated_at
    assert_equal Date.today, @order.initiated_at.to_date
    end
    def test_add_product
    product = Product.new
    @order << product
    assert_equal [product], @order.products
    assert_equal 1, @order.size
    assert !@order.empty?
    end
    

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63. def test_add_product
    product = Product.new
    @order << product
    assert_equal [product], @order.products
    assert_equal 1, @order.size
    assert !@order.empty?
    end
    def test_valid
    @order.user = User.new
    @order << Product.new
    assert @order.valid?
    end
    def test_valid_when_no_user
    @order << Product.new
    assert !@order.valid?
    end
    

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64. def test_valid_when_no_user
    @order << Product.new
    assert !@order.valid?
    end
    def test_valid_when_no_products
    @order.user = User.new
    assert !@order.valid?
    end
    def test_cancel
    @order.cancel
    assert_equal :canceled, @order.state
    end
    end
    

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65. class OrderTest < Minitest::Test
    def setup
    @order = Order.new
    end
    def around(&block)
    Order.stub :can_be_processed_today?, true, &block
    end
    def test_initiated_at
    assert_equal Date.today, @order.initiated_at.to_date
    end
    def test_add_product
    product = Product.new
    @order << product
    assert_equal [product], @order.products
    assert_equal 1, @order.size
    assert !@order.empty?
    end
    def test_valid
    @order.user = User.new
    @order << Product.new
    assert @order.valid?
    end
    def test_valid_when_no_user
    @order << Product.new
    assert !@order.valid?
    end
    def test_valid_when_no_products
    @order.user = User.new
    assert !@order.valid?
    end
    def test_cancel
    @order.cancel
    assert_equal :canceled, @order.state
    end
    end
    

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67. Какво трябва да
    тестваме?
    

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68. Query method
    car.top_speed
    user.name
    array.empty?
    

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69. Command method
    car.drive_to(supermarket)
    user.destroy!
    array << “1”
    

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70. Object
    Incomming Outgoing
    Send to self
    

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71. Incomming Send to self Outgoing
    object.method()
    def method
    private_method()
    end
    def other_method(object)
    object.method()
    end
    

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72. Query Command
    ▶︎ Incomming
    Check result
    directly
    Check side effects
    via public api
    Send to self
    (private)
    ✕
    No tests
    ✕
    No tests
    ◀ Outgoing
    ✕ 

    No tests
    Check with expect to
    send (mock)
    

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73. ▶︎ Incomming query
    class ArrayTest < Minitest::Test
    def test_empty
    array = [1]
    assert !array.empty?
    end
    

    end
    

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74. ▶︎ Incomming command
    class ArrayTest < Minitest::Test
    def test_empty
    array = [1]
    assert !array.empty?
    end
    end
    

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75. ◀ Outgoing command
    class MyObjectTest < Minitest::Test
    def test_my_method
    array = Minitest::Mock.new
    array.expect :clear, :returned
    custom = MyObject.new
    custom.clear array
    array.verify
    end
    end
    

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76. RSpec
    

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77. Dave Astels
    David Chelimsky

    release as 0.0.10 - July 2, 2008
    

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78. class ArrayTest < Minitest::Test
    def setup
    @array = []
    end
    def test_empty
    assert @array.empty?
    end
    def test_push
    @array << 1
    assert_equal [1], @array
    end
    end
    

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79. describe Array do
    before do
    @array = []
    end
    it "can tell when it is empty" do
    expect(@array).to be_empty
    end
    it "can filled with items" do
    @array << 1
    expect(@array).to eq [1]
    end
    end
    

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80. describe Array do
    before do
    @array = []
    end
    it "can tell when it is empty" do
    expect(@array).to be_empty
    end
    it "can filled with items" do
    @array << 1
    expect(@array).to eq [1]
    end
    end
    Example
    Group
    

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81. describe Array do
    before do
    @array = []
    end
    it "can tell when it is empty" do
    expect(@array).to be_empty
    end
    it "can filled with items" do
    @array << 1
    expect(@array).to eq [1]
    end
    end
    

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82. describe Array do
    before do
    @array = []
    end
    it "can tell when it is empty" do
    expect(@array).to be_empty
    end
    it "can filled with items" do
    @array << 1
    expect(@array).to eq [1]
    end
    end
    Setup
    

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83. describe Array do
    before do
    @array = []
    end
    it "can tell when it is empty" do
    expect(@array).to be_empty
    end
    it "can filled with items" do
    @array << 1
    expect(@array).to eq [1]
    end
    end
    

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84. describe Array do
    before do
    @array = []
    end
    it "can tell when it is empty" do
    expect(@array).to be_empty
    end
    it "can filled with items" do
    @array << 1
    expect(@array).to eq [1]
    end
    end
    Example
    

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85. describe Array do
    before do
    @array = []
    end
    it "can tell when it is empty" do
    expect(@array).to be_empty
    end
    it "can filled with items" do
    @array << 1
    expect(@array).to eq [1]
    end
    end
    

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86. describe Array do
    before do
    @array = []
    end
    it "can tell when it is empty" do
    expect(@array).to be_empty
    end
    it "can filled with items" do
    @array << 1
    expect(@array).to eq [1]
    end
    end
    Expectation
    

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87. describe Array do
    before do
    @array = []
    end
    it "can tell when it is empty" do
    expect(@array).to be_empty
    end
    it "can filled with items" do
    @array << 1
    expect(@array).to eq [1]
    end
    end
    

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88. describe Array do
    let(:array) { [] }
    it "can tell when it is empty" do
    expect(array).to be_empty
    end
    it "can filled with items" do
    array << 1
    expect(array).to eq [1]
    end
    end
    

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89. describe Array do
    let(:array) { [] }
    it "can tell when it is empty" do
    expect(array).to be_empty
    end
    it "can filled with items" do
    array << 1
    expect(array).to eq [1]
    end
    end
    

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90. describe Array do
    describe "#empty?" do
    it "returns true when empty" do
    expect(array).to be_empty
    end
    it "returns false when not empty" do
    array = [1]
    expect(array).to be_empty
    end
    end
    end
    

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92. Mocks
    

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94. Fake
    Used as a simpler implementation, e.g. using an in-memory
    database in the tests instead of doing real database access.
    

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95. Dummy
    Used when a parameter is needed for the tested method but
    without actually needing to use the parameter.
    

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96. Stub
    Test stubs are objects with pre-programmed behaviour.
    

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97. Spy
    Records arguments, return value, the value of this and
    exception thrown (if any) for all its calls.
    

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98. Mock
    Mocks are fake methods (like spies) with pre-programmed
    behaviour (like stubs) as well as pre-programmed
    expectations.
    A mock will fail your test if it is not used as expected.
    

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99. Test double
    Stub
    Spy
    Mock
    Fake
    Dummy
    

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100. describe PostsController do
     stub_rendering
     stub_current_user
     let(:post) { double 'Post' }
     describe "GET 'index'" do
     it "responds with posts of a given category" do
     allow(Post).to receive(:for_category).with(‘1’).and_return [post]
     get :index, category_id: '1'
     expect(controller).to respond_with [post]
     end
     end
     describe "POST 'create'" do
     it "creates new post" do
     allow(Post).to receive(:create).and_return post
     post :create, post: {title: 'test'}
     expect(Post).to have_received(:create).with(user: current_user, title: 'tes
     end
     end
     end
     

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101. Test Driven
     Development
     

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102. Automated
     Testing
     Test Driven
     Development
     

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103. Test Driven Development
     

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104. Test Driven Development
     1 Добавя се тест
     ... за несъществуващ код
     

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105. Test Driven Development
     1 Добавя се тест
     ... за несъществуващ код
     2 Пише се код
     ... колкото само тестът да мине
     

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106. Test Driven Development
     1 Добавя се тест
     ... за несъществуващ код
     3 Правят се подобрения
     ... подобрява се качеството на кода
     2 Пише се код
     ... колкото само тестът да мине
     

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107. Test Driven Development
     1 Добавя се тест
     ... за несъществуващ код
     3 Правят се подобрения
     ... подобрява се качеството на кода
     2 Пише се код
     ... колкото само тестът да мине
     

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108. describe Calculation do
     it "can sum numbers" do
     calculation = Calculation.new('1 + 1')
     expect(calculation.value).to eq 2
     end
     end
     

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109. uninitialized constant Calculation (NameError)
     

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110. class Calculation
     def initialize(expression)
     end
     def value
     end
     end
     

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111. View Slide

112. class Calculation
     def initialize(expression)
     @expression = expression
     end
     def value
     a, b = @expression.split '+'
     a.to_i + b.to_i
     end
     end
     

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114. describe Calculation do
     # . . .
     it "can subtract numbers" do
     calculation = Calculation.new('2 - 1')
     expect(calculation.value).to eq 1
     end
     end
     

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116. class Calculation
     def initialize(expression)
     @expression = expression
     end
     def value
     a, operation, b = @expression.split ' '
     if operation == '+'
     a.to_i + b.to_i
     elsif operation == '-'
     a.to_i - b.to_i
     end
     end
     end
     

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118. describe Calculation do
     # . . .
     it "can multiply numbers" do
     calculation = Calculation.new('3 * 2')
     expect(calculation.value).to eq 6
     end
     end
     

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120. class Calculation
     def initialize(expression)
     @expression = expression
     end
     def value
     a, operation, b = @expression.split ' '
     if operation == '+'
     a.to_i + b.to_i
     elsif operation == '-'
     a.to_i - b.to_i
     elsif operation == '*'
     a.to_i * b.to_i
     end
     end
     end
     

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122. describe Calculation do
     # . . .
     it "raises an error on unknown operation" do
     calculation = Calculation.new('3 ~ 2')
     expect { calculation.value }.to raise_error
     end
     end
     

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123. class Calculation
     def initialize(expression)
     @expression = expression
     end
     def value
     a, operation, b = @expression.split ' '
     if operation == '+'
     a.to_i + b.to_i
     elsif operation == '-'
     a.to_i - b.to_i
     elsif operation == '*'
     a.to_i * b.to_i
     else
     raise "Can't parse expression - #{@expression}"
     end
     end
     end
     

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124. class Calculation
     def initialize(expression)
     @expression = expression
     end
     OPERATIONS = {
     '+' => ->(a, b) { a + b },
     '-' => ->(a, b) { a - b },
     '*' => ->(a, b) { a * b }
     }
     def value
     a, operand, b = @expression.split ' '
     operation = OPERATIONS[operand]
     raise "Can't parse expression - #{@expression}" unless operation
     operation.call a.to_i, b.to_i
     end
     end
     

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125. describe Calculation do
     # . . .
     it "can divide numbers" do
     calculation = Calculation.new('6 / 3')
     expect(calculation.value).to eq 2
     end
     end
     

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126. View Slide

127. class Calculation
     def initialize(expression)
     @expression = expression
     end
     OPERATIONS = {
     '+' => ->(a, b) { a + b },
     '-' => ->(a, b) { a - b },
     '*' => ->(a, b) { a * b },
     '/' => ->(a, b) { a / b }
     }
     def value
     a, operand, b = @expression.split ' '
     operation = OPERATIONS[operand]
     raise "Can't parse expression - #{@expression}" unless operation
     operation.call a.to_f, b.to_f
     end
     end
     

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128. View Slide

129. class Calculation
     OPERATIONS = {
     '+' => ->(a, b) { a + b },
     '-' => ->(a, b) { a - b },
     '*' => ->(a, b) { a * b },
     '/' => ->(a, b) { a / b }
     }
     attr_reader :expression
     def initialize(expression)
     @expression = expression
     end
     def value
     @value ||= calculate_value
     end
     def to_s
     “#{expression} = #{value}"
     end
     private
     def calculate_value
     left, operand, right = expression.split ' '
     operation = OPERATIONS[operand]
     raise "Can't parse expression - #{@expression}" unless operation
     operation.call left.to_f, right.to_f
     end
     end
     

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130. Fragile Tests
     

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131. Bad fixture
     (fragile test)
     

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132. class OrderTest < Minitest::Test
     def test_expired
     order = Order.new(
     user: User.new,
     product: [Product.new]
     town: 'Sofia'
     initiated_at: 5.days.ago
     )
     assert order.expired?
     end
     end
     ✗
     

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133. class OrderTest < Minitest::Test
     def test_expired
     order = create_order initiated_at: 5.days.ago
     assert order.expired?
     end
     end
     ✔
     

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134. Behaviour changes
     (fragile test)
     

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135. class OrderTest < Minitest::Test
     def setup
     @order = Order.new
     end
     def test_valid
     @order.user = User.new
     @order << Product.new
     assert @order.valid?
     end
     def test_valid_when_no_user
     @order << Product.new
     assert !@order.valid?
     end
     def test_valid_when_no_products
     @order.user = User.new
     assert !@order.valid?
     end
     end
     ✗
     

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136. class OrderTest < Minitest::Test
     def setup
     @order = Order.new(
     user: User.new,
     products: [Product.new]
     )
     end
     def test_valid
     assert @order.valid?
     end
     def test_valid_when_no_user
     @order.user = nil
     assert !@order.valid?
     end
     def test_valid_when_no_products
     @order.products = []
     assert !@order.valid?
     end
     end
     ✔
     

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137. Indirection
     (fragile test)
     

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138. describe "Task" do
     describe ".complete_all" do
     it "completes a task by text mask" do
     task = create_task text: 'Create slides'
     other = create_task text: 'Create examples'
     Task.complete_all query: 'slides'
     expect(Task.ongoing).to eq [task]
     end
     end
     end
     ✗
     

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139. describe "Task" do
     describe ".complete_all" do
     it "completes tasks who match query" do
     task = create_task text: 'Create slides'
     Task.complete_all query: 'slides'
     expect { task.reload }.to change { task.completed? }.to true
     end
     it "doesn't complete tasks who don't match query" do
     task = create_task text: 'Create examples'
     Task.complete_all query: 'slides'
     expect { task.reload }.not_to change { task.completed? }
     end
     end
     end
     ✔
     

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140. describe "Task" do
     # . . .
     describe ".ongoing" do
     it "selects ongoing tasks" do
     ongoing = create_task state: :ongoing
     completed = create_task state: :completed
     expect(Task.ongoing).to eq ongoing
     end
     end
     end
     ✔
     

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141. Coupling
     (fragile test)
     

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142. describe Wallet do
     describe "#buy" do
     amount = true
     gateway = double 'Gateway'
     processor = double 'Processor'
     allow(gateway).to receive(:active?).and_return true
     allow(gateway).to receive(:processor).and_return processor
     allow(processor).to receive(:enough_money?).and_return true
     allow(processor).to receive(:process)
     Wallet.new(gateway).buy amount: 5
     expect(processor).to have_received(:process).with(5)
     end
     end
     ✗
     

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143. class Wallet
     def initialize(gateway)
     @gateway = gateway
     end
     def buy(amount: amount)
     return false if @gateway.active?
     processor = @gateway.processor
     return false if processor.enough_money?(amount)
     processor.process amount
     end
     end
     

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144. describe Wallet do
     describe "#buy" do
     amount = true
     processor = double 'Processor'
     allow(gateway).to receive(:process)
     Wallet.new(gateway).buy amount: 5
     expect(processor).to have_received(:process).with(5)
     end
     end
     ✔
     

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145. class Wallet
     def initialize(gateway)
     @gateway = gateway
     end
     def buy(amount: amount)
     @gateway.process amount
     end
     end
     

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146. Tools
     

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147. • Rspec
     • FactoryGirl
     • Timecop
     • DatabaseCleaner
     • Capybara
     

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148. Книги
     

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149. View Slide

150. View Slide

151. Обобщение
     

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152. • За какво са ни нужни тестове?
     • Какво е автоматичен тест?
     • Какви видове тестове има?
     • Какво е добър тест?
     • Как да пишем добри тестове?
     • Какво трябва да тестваме?
     • Какво са “Mocks”?
     • Какво е “RSpec”?
     • Какво е “Test Driven Development”?
     • Какво е “Fragile tests”?
     

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153. https://speakerdeck.com/rstankov/testing-ruby
     

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154. https://github.com/rstankov/talks-code
     

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155. View Slide

156. View Slide

157. @rstankov
     Благодаря за вниманието :)
     

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158. Въпроси?
     

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