How RSpec Works

Transcript

1. Sam Phippen How RSpec Works
2. Sam Phippen @samphippen Is an RSpec lead maintainer And works at Google
3. Sam Phippen Any code (except code from RSpec itself) in this talk is copyright Google under Apache V2
4. Sam Phippen Matz Hates Tests
5. Sam Phippen So RSpec is cancelled
6. Sam Phippen Thanks @samphippen samphippen@gmail.com
7. Sam Phippen Sam Phippen
8. Sam Phippen Sam Phippen
9. Sam Phippen gem “rspec”, “~> 3.8”
10. Sam Phippen specs: diff-lcs (1.3) rspec (3.8.0) rspec-core (~> 3.8.0) rspec-expectations (~> 3.8.0) rspec-mocks (~> 3.8.0) rspec-core (3.8.0) rspec-support (~> 3.8.0)
11. Sam Phippen rspec rspec-core rspec-mocks rspec-expectations
12. Sam Phippen rspec Meta gem that provides the other gems
13. Sam Phippen rspec-core describe, it, runner, let, etc
14. Sam Phippen rspec-mocks allow, double, to receive, etc
15. Sam Phippen rspec-expectations expect keyword and matchers
16. Sam Phippen rspec-support Internal code required to make rspec work
17. Sam Phippen gem “rspec-rails”, “~> 3.8”
18. Sam Phippen rspec-rails rspec rspec-mocks rspec-core rspec-expectations Rails specific code
19. Sam Phippen gem “rspec” gem “rspec-rails” !
20. Sam Phippen So, how does RSpec work?
21. Sam Phippen RSpec.describe "calculation" do it "can add numbers" do expect(1 + 1).to eq(2) end end
22. Sam Phippen RSpec.describe "calculation" do it "can add numbers" do expect(1 + 1).to eq(2) end end
23. Sam Phippen Example Group l/r-c/ example_group.rb
24. Sam Phippen bundle exec rspec
25. Sam Phippen Runner
26. Sam Phippen World Runner
27. Sam Phippen l/r-c/runner.rb l/r-c/world.rb
28. Sam Phippen —pattern=spec/**/*_spec.rb
29. Sam Phippen World Runner ExampleGroup ExampleGroup ExampleGroup
30. Sam Phippen —tag=foo (e.g describe, “…”, :foo do) —example=“calculates 4+4”
31. Sam Phippen Runner
32. Sam Phippen Runner Configuration Options
33. Sam Phippen Runner Configuration Options FilterManager
34. Sam Phippen World ExampleGroup ExampleGroup ExampleGroup FilterManager
35. Sam Phippen World ExampleGroup ExampleGroup ExampleGroup FilterManager
36. Sam Phippen World contains many ExampleGroups ready for execution
37. Sam Phippen RSpec.describe "calculation" do it "can add numbers" do expect(1 + 1).to eq(2) end end
38. Sam Phippen Example l/r-c/ example.rb
39. Sam Phippen A “test”
40. Sam Phippen RSpec.describe "eg1" do it "e1" it "e2" context "eg1_1" do it "e3" end context "eg2_1" do it "e3" end end
41. Sam Phippen EG EG E E EG E E E E
42. Sam Phippen So what about randomization?
43. Sam Phippen E EG E EG EG E E
44. Sam Phippen RSpec.describe "eg1" do before {} after {} around { |ex| ex.run} it "e1" end
45. Sam Phippen RSpec.describe "eg1" do before {} after {} around { |ex| ex.run} it "e1" end
46. Sam Phippen Hooks
 l/r-c/ hooks.rb
47. Sam Phippen Execute once before(:suite) after(:suite)
48. Sam Phippen Execute once per example group before(:context) after(:context)
49. Sam Phippen Execute once per example before after around
50. Sam Phippen EG E BS BC B E B A A
51. Sam Phippen EG E BC B A AC B
52. Sam Phippen RSpec core is only responsible for the structure and execution of your test suite
53. Sam Phippen RSpec.describe "calculation" do it "can add numbers" do expect(1 + 1).to eq(2) end end
54. Sam Phippen Expectation Provided by rspec-expectations
55. Sam Phippen RSpec.describe "calculation" do it "can add numbers" do expect(1 + 1).to eq(2) end end
56. Sam Phippen ExpectationTarget Matcher
57. Sam Phippen ExpectationTarget Matcher
58. Sam Phippen expect(…).to
59. Sam Phippen def to(matcher=nil, message=nil, &block) RSpec::Expectations:: PositiveExpectationHandler .handle_matcher(target, matcher, message, &block) end
60. Sam Phippen expect(…).to_not expect(…).not_to
61. Sam Phippen def not_to(matcher=nil, message=nil, &block) RSpec::Expectations:: NegativeExpectationHandler .handle_matcher(target, matcher, message, &block) end
62. Sam Phippen ExpectationTarget wraps a user object for matching
63. Sam Phippen RSpec.describe "calculation" do it "can add numbers" do expect(1 + 1).to eq(2) end end
64. Sam Phippen ExpectationTarget Matcher
65. Sam Phippen def eq(expected) BuiltIn::Eq .new(expected) end
66. Sam Phippen class Eq < BaseMatcher def match(expected, actual) actual == expected end end
67. Sam Phippen class BaseMatcher include RSpec::Matchers::Composable def matches?(actual) @actual = actual match(expected, actual) end end
68. Sam Phippen RSpec.describe "calculation" do it "can add numbers" do expect(1 + 1).to eq(2) end end
69. Sam Phippen Composable
70. Sam Phippen expect(…).to match([ a_kind_of(String), a_hash_including(a: 4) ])
71. Sam Phippen [ “any string”, {a: 4, b: 6.0}, ]
72. Sam Phippen class Match < BaseMatcher def match(expected, actual) return true if values_match?( expected, actual) actual.match(expected) end end
73. Sam Phippen class Match < BaseMatcher def match(expected, actual) return true if values_match?( expected, actual) actual.match(expected) end end
74. Sam Phippen def values_match?(expected, actual) expected = with_matchers_cloned(expected) Support::FuzzyMatcher.values_match?( expected, actual) end
75. Sam Phippen RSpec support is shared code between RSpec libraries
76. Sam Phippen def self.values_match?(expected, actual) if Hash === actual return hashes_match?(expected, actual) if Hash === expected elsif Array === expected && Enumerable === actual && !(Struct === actual) return arrays_match?(expected, actual.to_a) end return true if expected == actual begin expected === actual rescue ArgumentError # Some objects, like 0-arg lambdas on 1.9+, raise # ArgumentError for `expected === actual`. false end end
77. Sam Phippen You can’t read this.
78. Sam Phippen def self.values_match?(e, a) if Hash === a return hashes_match?(e, a) if Hash === e elsif Array === e && Enumerable === a && !(Struct === a) return arrays_match?( e, a) end
79. Sam Phippen def self.values_match?(e, a) if Hash === a return hashes_match?(e, a) if Hash === e elsif Array === e && Enumerable === a && !(Struct === a) return arrays_match?( e, a) end
80. Sam Phippen def self.hashes_match?( expected_hash, actual_hash) return false if expected_hash.size != actual_hash.size expected_hash.all? do |e_k, e_v| actual_value = actual_hash.fetch(e_k) { return false } values_match?(e_v, actual_value) end end
81. Sam Phippen def self.hashes_match?( expected_hash, actual_hash) return false if expected_hash.size != actual_hash.size expected_hash.all? do |e_k, e_v| actual_value = actual_hash.fetch(e_k) { return false } values_match?(e_v, actual_value) end end
82. Sam Phippen def self.hashes_match?( expected_hash, actual_hash) return false if expected_hash.size != actual_hash.size expected_hash.all? do |e_k, e_v| actual_value = actual_hash.fetch(e_k) { return false } values_match?(e_v, actual_value) end end
83. Sam Phippen def self.hashes_match?( expected_hash, actual_hash) return false if expected_hash.size != actual_hash.size expected_hash.all? do |e_k, e_v| actual_value = actual_hash.fetch(e_k) { return false } values_match?(e_v, actual_value) end end
84. Sam Phippen def self.hashes_match?( expected_hash, actual_hash) return false if expected_hash.size != actual_hash.size expected_hash.all? do |e_k, e_v| actual_value = actual_hash.fetch(e_k) { return false } values_match?(e_v, actual_value) end end
85. Sam Phippen def self.values_match?(e, a) if Hash === a return hashes_match?(e, a) if Hash === e elsif Array === e && Enumerable === a && !(Struct === a) return arrays_match?( e, a) end
86. Sam Phippen def self.arrays_match?( expected_list, actual_list) return false if expected_list.size!=actual_list.size expected_list.zip(actual_list).all? do |expected, actual| values_match?(expected, actual) end end
87. Sam Phippen def self.arrays_match?( expected_list, actual_list) return false if expected_list.size!=actual_list.size expected_list.zip(actual_list).all? do |expected, actual| values_match?(expected, actual) end end
88. Sam Phippen def self.arrays_match?( expected_list, actual_list) return false if expected_list.size!=actual_list.size expected_list.zip(actual_list).all? do |expected, actual| values_match?(expected, actual) end end
89. Sam Phippen RSpec recurses array and hash data structures, doing matches.
90. Sam Phippen def values_match(expected, actual) … (the code we saw earlier) return true if expected == actual begin expected === actual rescue ArgumentError # Some objects, like 0-arg lambdas on # 1.9+, raise # ArgumentError for `expected === actual`. false end end
91. Sam Phippen def values_match(expected, actual) … (the code we saw earlier) return true if expected == actual begin expected === actual rescue ArgumentError # Some objects, like 0-arg lambdas on # 1.9+, raise # ArgumentError for `expected === actual`. false end end
92. Sam Phippen def values_match(expected, actual) … (the code we saw earlier) return true if expected == actual begin expected === actual rescue ArgumentError # Some objects, like 0-arg lambdas on # 1.9+, raise # ArgumentError for `expected === actual`. false end end
93. Sam Phippen /a/ === “a” lambda { |x| x == 1 } === 1 Any Rspec matcher === a value it matches
94. Sam Phippen RSpec aliases === to matches? On matchers
95. Sam Phippen So let’s put it all back together
96. Sam Phippen expect(…).to match([ a_kind_of(String), a_hash_including(a: 4) ])
97. Sam Phippen [ “any string”, {a: 4, b: 6.0}, ]
98. Sam Phippen Call arrays_match?
99. Sam Phippen [ “any string”, {a: 4, b: 6.0}, ]
100. Sam Phippen Call === on “a_kind_of(String)”
101. Sam Phippen [ “any string”, ✅ {a: 4, b: 6.0}, ]
102. Sam Phippen Call === on a_hash_including?(a: 4)
103. Sam Phippen [ “any string”, ✅ {a: 4, b: 6.0}, ✅ ]
104. Sam Phippen Match returns true
105. Sam Phippen RSpec expectations contains expect, and matching logic.
106. Sam Phippen rspec-mocks
107. Sam Phippen RSpec.describe "mocking" do it “adds a foo method" do allow(foo).to receive(:bees) expect(foo.bees).to eq(nil) end end
108. Sam Phippen RSpec.describe "mocking" do it “adds a foo method" do allow(foo).to receive(:bees) expect(foo.bees).to eq(nil) end end
109. Sam Phippen AllowanceTarget
110. Sam Phippen AllowanceTarget TargetBase
111. Sam Phippen AllowanceTarget calls #delegate_to with :setup_allowance on TargetBase
112. Sam Phippen expect(foo).to receive
113. Sam Phippen ExpectationTarget calls #delegate_to with :setup_expectation on TargetBase
114. Sam Phippen AllowanceTarget TargetBase
115. Sam Phippen TargetBase defines #to on AllowanceTarget
116. Sam Phippen The defined #to calls :setup_allowance on matchers passed to #to
117. Sam Phippen This meta programming step allows deduplication with ExpectationTarget
118. Sam Phippen AllowanceTarget TargetBase
119. Sam Phippen RSpec.describe "mocking" do it “adds a foo method" do allow(foo).to receive(:bees) expect(foo.bees).to eq(nil) end end
120. Sam Phippen Receive matcher handles stubbing and mocking for RSpec
121. Sam Phippen AllowanceTarget#to calls setup_allowance on the passed matcher
122. Sam Phippen AllowanceTarget TargetBase Receive
123. Sam Phippen Receive#setup_allowance creates a Proxy for object
124. Sam Phippen AllowanceTarget TargetBase Receive Proxy
125. Sam Phippen Receive#setup_allowance Calls #add_stub on the Proxy
126. Sam Phippen Proxy manages all mocks and stubs for an object
127. Sam Phippen Proxy#add_stub creates a MethodDouble for the stubbed method
128. Sam Phippen AllowanceTarget TargetBase Receive Proxy Method double
129. Sam Phippen MethodDouble saves the original implementation
130. Sam Phippen MethodDouble creates the stub implementation
131. Sam Phippen RSpec.describe "mocking" do it “adds a foo method" do allow(foo).to receive(:bees) expect(foo.bees).to eq(nil) end end
132. Sam Phippen Calling foo.bees calls the stubbed implementation
133. Sam Phippen Call foo.bees
134. Sam Phippen Method double Call foo.bees
135. Sam Phippen Proxy Method double Call foo.bees
136. Sam Phippen Invoke stub Proxy Method double Call foo.bees
137. Sam Phippen Invoke stub Return value Proxy Method double Call foo.bees
138. Sam Phippen RSpec.describe "mocking" do it “adds a foo method" do allow(foo).to receive(:bees) expect(foo.bees).to eq(nil) end end
139. Sam Phippen At the end of the test, the MethodDouble puts the original method back on the object
140. Sam Phippen And that’s stubs
141. Sam Phippen RSpec.describe "mocking" do it “adds a foo method" do expect(foo).to receive(:bees) expect(foo.bees).to eq(nil) end end
142. Sam Phippen ExpectationTarget TargetBase Receive Proxy Method double
143. Sam Phippen At the end of each test, RSpec invokes RSpec::Mocks.verify
144. Sam Phippen RSpec::Mocks.verify enumerates all MethodDoubles
145. Sam Phippen MethodDoubles raise if their conditions weren’t met
146. Sam Phippen RSpec mocks has a lot more power, this is a high level overview
147. Sam Phippen rspec-core describe, it, runner, let, etc
148. Sam Phippen rspec-expectations expect keyword and matchers
149. Sam Phippen rspec-mocks allow, double, to receive, etc
150. Sam Phippen Thanks @samphippen samphippen@gmail.com