Testing Ruby

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

Transcript

1. Testing Ruby Radoslav Stankov 04/12/2014
2. Кой съм аз? @rstankov http://rstankov.com http://github.com/rstankov
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
6. I have a plan!
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”?
8. За какво са ни нужни тестове?
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}"
17. class Calculation # ... def to_s "#{expression} = #{value}" end end
18. puts Calculation.new("1 + 1") puts Calculation.new("2 - 1") puts Calculation.new("3 * 2")
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 :)'
20. def assert_calculation(expression, expected) calculation = Calculation.new(expression) if calculation.value != expected raise "#{calculation}, but expected #{expected}" end end
21. assert_calculation '1 + 1', 2 assert_calculation '2 - 1', 1 assert_calculation '3 * 2', 6 puts 'Everything okay :)'
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
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
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
25. Какво е автоматичен тест?
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
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
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
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
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
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
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
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
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
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
37. Kent Beck • based on SUnit (Smalltalk) • released around 1998 xUnit
38. Какви видове тестове има?
39. System under test (SUT) Tests Unit test Integration test Acceptance test SUD
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
41. Какво е добър тест?
42. “Не трябва да губя енергия за пускане на тестове ” Лесни за пускане
43. “Пускането на тестове не трябва да ме разсейва от проблема, който решавам ” Бързи
44. “Не трябва да губя излишна енегрия зада разбера даден тест” Прости
45. “Трябва да имам чувството, че ако тестовете ми минават, значи кода ми работи” Надежни
46. “Не трябва да се налага да се пренаписват при всяка промяна ” Гъвкави
47. “Когато даден тест се счупи, трябва да знам точно кой тест се е счупил и защо” Локализирани
48. Как да пишем добри тестове?
50. 4 Phase testing
51. 4 Phase testing Setup
52. 4 Phase testing Setup Action
53. 4 Phase testing Setup Action Assertion
54. 4 Phase testing Setup Action Assertion Teardown
55. 4 Phase testing Setup Action Assertion Teardown
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?
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
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
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
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
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
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
67. Какво трябва да тестваме?
68. Query method car.top_speed user.name array.empty?
69. Command method car.drive_to(supermarket) user.destroy! array << “1”
70. Object Incomming Outgoing Send to self
71. Incomming Send to self Outgoing object.method() def method private_method() end def other_method(object) object.method() end
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)
73. ▶︎ Incomming query class ArrayTest < Minitest::Test def test_empty array = [1] assert !array.empty? end 
 end
74. ▶︎ Incomming command class ArrayTest < Minitest::Test def test_empty array = [1] assert !array.empty? end end
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
76. RSpec
77. Dave Astels David Chelimsky
 release as 0.0.10 - July 2, 2008
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
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
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
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
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
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
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
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
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
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
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
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
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
92. Mocks
94. Fake Used as a simpler implementation, e.g. using an in-memory database in the tests instead of doing real database access.
95. Dummy Used when a parameter is needed for the tested method but without actually needing to use the parameter.
96. Stub Test stubs are objects with pre-programmed behaviour.
97. Spy Records arguments, return value, the value of this and exception thrown (if any) for all its calls.
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.
99. Test double Stub Spy Mock Fake Dummy
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
101. Test Driven Development
102. Automated Testing Test Driven Development
103. Test Driven Development
104. Test Driven Development 1 Добавя се тест ... за несъществуващ код
105. Test Driven Development 1 Добавя се тест ... за несъществуващ код 2 Пише се код ... колкото само тестът да мине
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
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
108. describe Calculation do it "can sum numbers" do calculation = Calculation.new('1 + 1') expect(calculation.value).to eq 2 end end
109. uninitialized constant Calculation (NameError)
110. class Calculation def initialize(expression) end def value end end
112. class Calculation def initialize(expression) @expression = expression end def value a, b = @expression.split '+' a.to_i + b.to_i end end
114. describe Calculation do # . . . it "can subtract numbers" do calculation = Calculation.new('2 - 1') expect(calculation.value).to eq 1 end end
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
118. describe Calculation do # . . . it "can multiply numbers" do calculation = Calculation.new('3 * 2') expect(calculation.value).to eq 6 end end
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
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
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
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
125. describe Calculation do # . . . it "can divide numbers" do calculation = Calculation.new('6 / 3') expect(calculation.value).to eq 2 end end
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
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
130. Fragile Tests
131. Bad fixture (fragile test)
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 ✗
133. class OrderTest < Minitest::Test def test_expired order = create_order initiated_at: 5.days.ago assert order.expired? end end ✔
134. Behaviour changes (fragile test)
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 ✗
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 ✔
137. Indirection (fragile test)
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 ✗
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 ✔
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 ✔
141. Coupling (fragile test)
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 ✗
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
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 ✔
145. class Wallet def initialize(gateway) @gateway = gateway end def buy(amount: amount) @gateway.process amount end end
146. Tools
147. • Rspec • FactoryGirl • Timecop • DatabaseCleaner • Capybara
148. Книги
151. Обобщение
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”?
153. https://speakerdeck.com/rstankov/testing-ruby
154. https://github.com/rstankov/talks-code
157. @rstankov Благодаря за вниманието :)
158. Въпроси?