Testing 201

Transcript

1. TESTING 201 OR: GREAT EXPECTATIONS JOE MASTEY, APRIL 2019
2. EVERYONE IS DOING THEIR BEST
3. HEURISTICS, NOT RULES
4. THIS STUFF SHOULDN’T SLOW YOU DOWN
5. PROLOGUE: THE TROUBLE WITH A SIMPLE TEST
6. class CreateShipmentHistoryReport attr_accessor :user, :shipments def initialize(user) @user = user @shipments = user.shipments end def process shipments.sort_by(&:created_at) data = shipments.map do |shipment| shipment.to_json.values + [ shipment.user.name, shipment.product.name ] end file = CSV.open(tmp_filename) do |csv| csv << shipments.first.to_json.keys + ['user', 'product'] data.map do |row| csv << row end end persist_csv_to_s3(file) notify_user(user.email) file end end
7. class CreateShipmentHistoryReport attr_accessor :user, :shipments def initialize(user) @user = user @shipments = user.shipments end
8. def process shipments.sort_by(&:created_at) data = shipments.map do |shipment| shipment.to_json.values + [ shipment.user.name, shipment.product.name ] end # continued below...
9. # ... process continued file = CSV.open(tmp_filename) do |csv| csv << shipments.first.to_json.keys + ['user', 'product'] data.map do |row| csv << row end end persist_csv_to_s3(file) notify_user(user.email) file end
10. class CreateShipmentHistoryReport attr_accessor :user, :shipments def initialize(user) @user = user @shipments = user.shipments end def process shipments.order('created_at desc') data = shipments.map do |shipment| shipment.to_json.values + [ shipment.user.name, shipment.product.name ] end file = CSV.open(tmp_filename) do |csv| csv << shipments.first.to_json.keys + ['user', 'product'] data.map do |row| csv << row end end persist_csv_to_s3(file) notify_user(user.email) file end end
11. describe CreateShipmentHistoryReport do describe "#process" do it "generates an array of strings" do expect(csv_data.length).to eq(shipments.length) expect(csv_data).to all(be_an(Array)) end it "generates an output record for each input, sorted by date" do expect(csv_data).to eq(output_records) end end end
12. let(:subject) { described_class.new(user).process } let(:csv_data) { CSV.parse(subject) }
13. let(:user) { create(:user, :signup_complete) } let(:subscription) { create(:subscription) } before do user.subscription << subscription end
14. let(:product) { create(:product) } let!(:shipment) { create(:shipment, product: product, created_at: 2.days.ago) } let(:output_records) do [ [shipment.created_on, shipment.completed_on, user.name, product.name] ] end before do expect(user) .to receive(:shipments) .and_return([shipment]) end end
15. before do expect_any_instance_of(described_class) .to receive(:save_to_s3) .and_return(true) expect_any_instance_of(described_class) .to receive(:email_user) .and_return(true) end
16. let(:product_1) { create(:product) } let(:product_2) { create(:product) } let(:product_3) { create(:product) } let(:product_4) { create(:product) }
17. let!(:shipment_1) { create(:shipment, product: product_1, created_at: 2.days.ago) } let!(:shipment_2) { create(:shipment, product: product_2, created_at: 3.days.ago) } let!(:shipment_3) { create(:shipment, product: product_3, created_at: 4.days.ago) } let!(:shipment_4) { create(:shipment, product: product_4, created_at: 5.days.ago) }
18. let(:shipments) do [ shipment_1, shipment_2, shipment_3, shipment_4 ] end
19. let(:output_records) do [ [shipment_4.created_on, shipment_4.completed_on, user.name, product_4.name], [shipment_3.created_on, shipment_3.completed_on, user.name, product_3.name], [shipment_2.created_on, shipment_2.completed_on, user.name, product_2.name], [shipment_1.created_on, shipment_1.completed_on, user.name, product_1.name], ] end
20. it "generates an output record for each input, sorted by date" do expect(csv_data).to eq(output_records) end
21. describe CreateShipmentHistoryReport do describe "#process" do let(:user) { create(:user, :signup_complete) } let(:subscription) { create(:subscription) } let(:product_1) { create(:product) } let(:product_2) { create(:product) } let(:product_3) { create(:product) } let(:product_4) { create(:product) } let!(:shipment_1) { create(:shipment, product: product_1, created_at: 2.days.ago) } let!(:shipment_2) { create(:shipment, product: product_2, created_at: 3.days.ago) } let!(:shipment_3) { create(:shipment, product: product_3, created_at: 4.days.ago) } let!(:shipment_4) { create(:shipment, product: product_4, created_at: 5.days.ago) } let(:subject) { described_class.new(user).process } let(:csv_data) { CSV.parse(subject) } let(:shipments) do [ shipment_1, shipment_2, shipment_3, shipment_4 ] end let(:output_records) do [ [shipment_4.created_on, shipment_4.completed_on, user.name, product_4.name], [shipment_3.created_on, shipment_3.completed_on, user.name, product_3.name], [shipment_2.created_on, shipment_2.completed_on, user.name, product_2.name], [shipment_1.created_on, shipment_1.completed_on, user.name, product_1.name], ] end before do user.subscription << subscription expect(user) .to receive(:shipments) .and_return(shipments) expect_any_instance_of(described_class) .to receive(:save_to_s3) .and_return(true) expect_any_instance_of(described_class) .to receive(:email_user) .and_return(true) end it "generates an array of strings" do expect(csv_data.length).to eq(shipments.length) expect(csv_data).to all(be_an(Array)) end it "generates an output record for each input, sorted by date" do expect(csv_data).to eq(output_records) end end end
22. FOCUSING ON THE WRONG THINGS
23. THE 3 ROLES OF TESTING (IN ORDER)
24. 1. DESIGN FEEDBACK 2. DOCUMENTATION 3. VERIFICATION
25. TESTS AS DESIGN FEEDBACK
26. A NOTE ON TDD
27. CODE THAT’S DIFFICULT TO TEST IS TRYING TO TELL YOU SOMETHING IMPORTANT
28. IT’S EASIER TO WORK WITH OBJECTS IN SMALL CHUNKS.
29. let(:csv_data) { CSV.parse(subject) } before do expect_any_instance_of(described_class) .to receive(:save_to_s3) .and_return(true) expect_any_instance_of(described_class) .to receive(:email_user) .and_return(true) end
30. before do expect_any_instance_of(described_class) .to receive(:save_to_s3) .and_return(true) expect_any_instance_of(described_class) .to receive(:email_user) .and_return(true) end
31. def data(shipments) shipments.sort_by!(&:created_at) shipments.map do |shipment| shipment.to_json.values + [ shipment.user.name, shipment.product.name ] end end def headers shipments.first.to_json.keys + ['user', 'product'] end
32. file = CSV.open(tmp_filename) do |csv| csv << headers data(shipments).map { |row| csv << row } end
33. it "generates an output record for each input, sorted by date" do subject = described_class.new(user) expect(subject.data).to eq(output_records) end
34. before do # expect_any_instance_of(described_class) # .to receive(:save_to_s3) # .and_return(true) # expect_any_instance_of(described_class) # .to receive(:email_user) # .and_return(true) end
35. before do expect(user) .to receive(:shipments) .and_return(shipments) end
36. class CreateShipmentHistoryReport def initialize(user, shipments: user.shipments) @user = user @shipments = shipments end end
37. before do # expect(user) # .to receive(:shipments) # .and_return(shipments) end described_class.new(user, shipments)
38. def data(shipments) shipments.sort_by!(&:created_at) shipments.map do |shipment| shipment.to_json.values + [ shipment.user.name, shipment.product.name ] end end def headers shipments.first.to_json.keys + ['user', 'product'] end
39. def serialize(shipment) { created_on: shipment.created_on, completed_on: shipment.completed_on, user: shipment.user.name, product: shipment.product.name, } end
40. def serialize(shipment) { created_on: shipment.created_on, completed_on: shipment.completed_on, user: shipment.user.name, product: shipment.product.name, } end def data(shipments) shipments.sort_by(&:created_at).map do |shipment| serialize(shipment) end end def headers serialize(shipments.first).keys end
41. describe "#serialize" do it "serializes some shipment and user data" do shipment = create_shipment(date: 2.days.ago) report = described_class.new(user, []) result = report.serialize(shipment) expect(result).to eq({ created_on: shipment.created_on, completed_on: shipment.completed_on, user: shipment.user.name, product: shipment.product.name, }) end end
42. # let(:output_records) do # [ # [shipment_4.created_on, shipment_4.completed_on, # user.name, product_4.name], # [shipment_3.created_on, shipment_3.completed_on, # user.name, product_3.name], # [shipment_2.created_on, shipment_2.completed_on, # user.name, product_2.name], # [shipment_1.created_on, shipment_1.completed_on, # user.name, product_1.name], # ] # end
43. describe "ordering" do it "reorders shipments by their creation date" do shipment_1, shipment_2 report = described_class.new(user, [shipment_1, shipment_2]) result = report.data expect(result.map(&:first)).to eq( [shipment_2.created_on, shipment_1.created_on] ) end end
44. CREATE AS FEW RECORDS AS YOU CAN (AND ONLY RELATED ONES)
45. let(:user) { create(:user, :signup_complete) } let(:subscription) { create(:subscription) } before do user.subscription << subscription end
46. Factory AR records AR queries create(:user) 1 10 create(:meal) 5 41 create(:full_menu) 94 584 create(:weekly_basket) 104 644 create(:user, :with_order_history) 379 2336
47. let(:user) do instance_double(User, email: "test@test.com", shipments: shipments) end
48. let(:user) { User.new(email: "test@test.com", name: "Joe") }
49. describe "ordering" do it "reorders shipments by their creation date" do shipment_1, shipment_2 report = described_class.new(user, [shipment_1, shipment_2]) result = report.data expect(result.map(&:first)).to eq( [shipment_2.created_on, shipment_1.created_on] ) end end
50. PAY ATTENTION TO SIMILARITY AND DIFFERENCE
51. let(:product_1) { create(:product) } let(:product_2) { create(:product) } let(:product_3) { create(:product) } let(:product_4) { create(:product) }
52. let!(:shipment_1) { create(:shipment, product: product_1, created_at: 2.days.ago) } let!(:shipment_2) { create(:shipment, product: product_2, created_at: 3.days.ago) } let!(:shipment_3) { create(:shipment, product: product_3, created_at: 4.days.ago) } let!(:shipment_4) { create(:shipment, product: product_4, created_at: 5.days.ago) }
53. let(:shipments) do [ shipment_1, shipment_2, shipment_3, shipment_4 ] end
54. let(:output_records) do [ [shipment_4.created_on, shipment_4.completed_on, user.name, product_4.name], [shipment_3.created_on, shipment_3.completed_on, user.name, product_3.name], [shipment_2.created_on, shipment_2.completed_on, user.name, product_2.name], [shipment_1.created_on, shipment_1.completed_on, user.name, product_1.name], ] end
55. def create_shipment(date:) product = create(:product) create(:shipment, product: product, created_at: date) end
56. describe "ordering" do it "reorders shipments by their creation date" do old = create_shipment(date: 9.days.ago) new = create_shipment(date: 2.days.ago) report = described_class.new(user, [new, old]) result = report.data expect(result.map(&:first)).to eq( [old.created_on, new.created_on] ) end end
57. # let(:product_1) { create(:product) } # let(:product_2) { create(:product) } # let(:product_3) { create(:product) } # let(:product_4) { create(:product) } # let!(:shipment_1) { create(:shipment, product: product_1, # created_at: 2.days.ago) } # let!(:shipment_2) { create(:shipment, product: product_2, # created_at: 3.days.ago) } # let!(:shipment_3) { create(:shipment, product: product_3, # created_at: 4.days.ago) } # let!(:shipment_4) { create(:shipment, product: product_4, # created_at: 5.days.ago) } # # let(:shipments) do # [ # shipment_1, # shipment_2, # shipment_3, # shipment_4 # ] # end # let(:output_records) do # [ # [shipment_4.created_on, shipment_4.completed_on, # user.name, product_4.name], # [shipment_3.created_on, shipment_3.completed_on, # user.name, product_3.name], # [shipment_2.created_on, shipment_2.completed_on, # user.name, product_2.name], # [shipment_1.created_on, shipment_1.completed_on, # user.name, product_1.name], # ] # end
58. TRY TO REDUCE COMPLEXITY, NOT HIDE IT
59. def create_shipment(date:) product = create(:product) create(:shipment, product: product, created_at: date) end
60. it "generates an output record for each input, sorted by date" do expect(csv_data).to eq(output_records) end
61. DON’T DO TOO MUCH WORK
62. def process def serialize(shipment) def data(shipments) def headers def save_to_s3(file) def notify_user(email)
64. TESTS AS DOCUMENTATION
65. WRITE TESTS FOR HUMANS, NOT FOR THE COMPILER
66. it "generates an output record for each input, sorted by date" do expect(csv_data).to eq(output_records) end
67. describe "ordering" do it "reorders shipments by their creation date" do old = create_shipment(date: 9.days.ago) new = create_shipment(date: 2.days.ago) report = described_class.new(user, [new, old]) result = report.data expect(result.map(&:first)).to eq( [old.created_on, new.created_on] ) end end
68. it "serializes data as an array" do users = create_list(:user, 3) response = subject.create(User.all).process response = response[0][4] expect(response).to eq(users.first.name) end
69. it "serializes data as an array" do users = create_list(:user, 3) serialized_users = subject.create(User.all).to_hashes response = serialized_users.first.full_name expect(response).to eq(users.first.name) end
70. TRY TO STICK TO A GIVEN/ WHEN/THEN STRUCTURE
71. describe "ordering" do it "reorders shipments by their creation date" do old = create_shipment(date: 9.days.ago) new = create_shipment(date: 2.days.ago) report = described_class.new(user, [new, old]) result = report.data expect(result.map(&:first)).to eq( [old.created_on, new.created_on] ) end end
72. describe "ordering" do it "reorders shipments by their creation date" do # Given old = create_shipment(date: 9.days.ago) new = create_shipment(date: 2.days.ago) # When report = described_class.new(user, [new, old]) result = report.data # Then expect(result.map(&:first)).to eq( [old.created_on, new.created_on] ) end end
73. it "reorders shipments by their creation date" do old = create_shipment(date: 9.days.ago) new = create_shipment(date: 2.days.ago) report = described_class.new(user, [new, old]) expect(report.data.map(&:first)).to eq([old, new]) end
74. before do expect_any_instance_of(described_class) .to receive(:save_to_s3) .and_return(true) expect_any_instance_of(described_class) .to receive(:email_user) .and_return(true) end
75. USING G/W/T EMPHASIZES SAMENESS AND DIFFERENCE.
76. it "returns order units summed, divided by units per shipper" do create_store_order(count_units: 4) create_store_order(count_units: 8) subject = described_class.new(store_orders: store_orders) total_shippers = subject.total_shipper_count expect(total_shippers).to eq(3) end
77. it "returns a ceiling rounded value" do create_store_order(count_units: 7) subject = described_class.new(store_orders: store_orders) total_shippers = subject.total_shipper_count expect(total_shippers).to eq(2) end
78. let!(:shipment_1) { create(:shipment, product: product_1, created_at: 2.days.ago) } let!(:shipment_2) { create(:shipment, product: product_2, created_at: 3.days.ago) } let!(:shipment_3) { create(:shipment, product: product_3, created_at: 4.days.ago) } let!(:shipment_4) { create(:shipment, product: product_4, created_at: 5.days.ago) }
79. TESTS DON’T NEED TO BE (TOO) DRY
80. it "returns order units summed, divided by units per shipper" do create_store_order(count_units: 4) create_store_order(count_units: 8) subject = described_class.new(store_orders: store_orders) total_shippers = subject.total_shipper_count expect(total_shippers).to eq(3) end it "returns a ceiling rounded value" do create_store_order(count_units: 7) subject = described_class.new(store_orders: store_orders) total_shippers = subject.total_shipper_count expect(total_shippers).to eq(2) end
81. describe "#total_shipper_count" do subject { described_class.new(store_orders: StoreOrder.all) } context "even division" do let!(:order1) { create_store_order(count_units: 4) } let!(:order2) { create_store_order(count_units: 8) } let(:expected_total) { 3 } it "returns order units summed, divided by units per shipper" do expect(subject.total_shipper_count).to eq(expected_total) end end end
82. context "rounding" do let!(:order) { create_store_order(count_units: 7) } let(:expected_total) { 2 } it "returns order units summed, divided by units per shipper" do expect(subject.total_shipper_count).to eq(expected_total) end end
83. subject(:service) { described_class.new } it "sends email" do expect(service).to receive(:notify_user) end after do service.process end
84. THE FEELING OF NEEDING TO DRY YOUR TESTS IS ACTUALLY DESIGN FEEDBACK
85. SAY WHAT YOU MEAN, LITERALLY
86. def user_summary(user) "(#{user.id}) #{user.full_name}, #{user.role}" end it "returns a user summary for printing" do user = User.new(id: 5, full_name: "Dave G", role: :admin) expected = "(#{user.id}) #{user.full_name}, #{user.role}" summary = user_summary(user) expect(summary).to eq(expected) end
87. it "returns a user summary for printing" do user = User.new(id: 5, full_name: "Dave G", role: :admin) summary = user_summary(user) expect(summary).to eq("(5) Dave G, admin") end
88. LEVERAGE YOUR TOOLS TO HELP GUIDE READERS
89. describe "#process" do it "return value" end describe "#process" do it "returns the number of records correctly persisted" end
90. describe CreateShipmentHistoryReport do describe "#sorted_shipments" do it "returns an empty array when there are no shipments" end end be rspec ./spec/services/create_shipment_history_report_spec.rb —format=‘documentation’ # CreateShipmentHistoryReport#sorted_shipments returns an empty array when there are no shipments
91. it “picks randomly, but correctly” do double1 = double double2 = double result = [double1, double2].sample expect(result).to eq(double1) end # expected: #<Double (anonymous)> # got: #<Double (anonymous)>
92. it “picks randomly, but correctly” do double1 = double("first record") double2 = double("second record”) result = [double1, double2].sample expect(result).to eq(double1) end # expected: #<Double "first record"> # got: #<Double "second record">
93. it "checks result size" do arr = [1,2,3] response = arr.length expect(response > 3).to be_true end # expected true # got false
94. it "checks result size" do arr = [1,2,3] response = arr.length expect(response).to be > 3 end # expected: > 3 # got: 3
95. it "checks validity of a record" do thing = double(valid?: true) expect(thing.valid?).to be_false end # expected: false # got: true
96. it "checks validity of a record" do thing = double("order", valid?: true) expect(thing).not_to be_valid end # expected `#<Double "order">.valid?` to return false, got true
98. TESTS AS VERIFICATION
99. TEST WHAT’S IMPORTANT, RISKY, OR WHAT’S CHEAP
100. YOU CAN’T HAVE 100% COVERAGE
101. DON’T TEST WHAT YOU DON’T OWN
102. validate :status, presence: true it { should validate_presence_of(:status) }
103. validate :failure_message, presence: true, if: :failed? it "sometimes requires failure_message" do job = JobLog.new(status: :failed) expect(job).to validate_presence_if(:failure_message) job = JobLog.new(status: :completed) expect(job).not_to validate_presence_if(:failure_message) end
104. DON’T BE AFRAID TO DELETE YOUR TESTS
105. it "generates an array of strings” do expect(csv_data.length).to eq(shipments.length) expect(csv_data).to all(be_an(Array)) end
106. BEWARE OF OVER-MOCKING
107. def user_summary(user) "(#{user.id}) #{user.full_name}, #{user.role}" end it "returns a user summary for printing, bad" do user = double(id: 5, full_name: "Dave G", role: :admin) response = user_summary(user) expect(response).to eq("(5) Dave G, admin") end
108. it "returns a user summary for printing, better" do user = instance_double(User, id: 5, full_name: "Dave G", role: :admin) response = user_summary(user) expect(response).to eq("(5) Dave G, admin") end
109. it "returns a user summary for printing, better" do user = User.new(id: 5, full_name: "Dave G", role: :admin) expect(user_summary(user)).to eq("(5) Dave G, admin") end
111. IN SUMMARY!
112. 2. ACTUALLY, JUST DELETE THEM 3. TINY PIGS ARE WAY CUTER THAN CATS 1. KEEP YOUR TESTS MOIST
113. 2. WRITE TESTS FOR HUMANS 3. TINY PIGS ARE WAY CUTER THAN CATS 1. USE TESTS TO DRIVE DESIGN
114. THANKS!