Voxxed Days Brussels 2023 - Your Tests also need some Architecting

Transcript

1. 1 Jonas Geiregat Your tests also need some architecting @jonas_grgt
2. Prevent regression
3. Refactor freely
4. Make our systems evolvable at a steady pace SPEED TIME SPEED TIME
5. Serve as documentation
6. Guide our design
7. Release with confidence
8. The reality of tests - Brittle - Hard to maintain - Complex - Cryptic - Did not guide - Slow - Skipped
9. The benefits of test should outweigh the cost of writing, running and maintaining them
10. “Architecture is about the important stuff. Whatever that is.” -- Ralph Johnson
11. Architecture is about making tradeoffs with the right context.
12. “Architects are like sherpas that guide” -- Martin Fowler - Who Needs an Architect?
13. How did we end up here?
14. What do we test ? What is the system under test ?
15. Engineers love solving problems, that have zero business value because it’s considered fun. Why do we write code ?
16. “The trigger for writing a test is not a new class nor a new public method” -- Ian Cooper - TDD, Where Did It All Go Wrong
17. The main reason for a test to exists is because there is a requirement that describes a behavior of the system
18. Test your behavioral contract whatever that means technically
19. BDD is a misunderstood reaction to the misconceptions of TDD.
20. So you want us to only write integration tests ? -- Fellow developers - coffee machine
21. unit tests end to end tests integration tests slow / expensive fast / cheap Does the classical testing Pyramid still stand ?
22. The type of test: unit, integration, acceptance etc .. is how you are testing. It is a detail, that is seldom relevant.
23. What: an integrated, behavior or impl. detail test is
24. integrated impl. detail tests integration behavior / feature / use-case tests How vs What end to end tests unit tests integration tests Microservices testing honeycomb Kent C. Dodds pyramid static static
25. Define and communicate your test shape.
26. So how do we put this all into code ?
27. Test should not be viewed in the same manner one views production code. It’s a different context. Different rules are at play.
28. Avoid abstractions
29. Keep your readers in your test method Minimize setup and tear-down logic to only the technical
30. Cyclomatic complexity of a test should be 1
31. Classic test naming convention class InvoiceServiceTest { VS Test naming convention based on requirement/feature/behavior class PayInvoiceFeatureTest { class MarkInvoiceAsProcessedFeatureTest { class CreateInvoiceTemplateFeatureTest { class ProcessInvoiceFeatureTest { class AddInvoiceLineFeatureTest {
32. Do not communicate what you are testing @Test void testExpireInvoice() { @Test void testStartReportJob() { @Test void addPineappleToppingToPizzaTest() {
33. Don’t communicate what you are testing but why you need a test The why captures the behaviour
34. The why @Test void testExpireInvoice() { @Test void unExpiredInvoice_shouldExpire_after30DaysAfterPublicationDate() { @Test void testStartReportJob() { @Test void startingANewReportJob_shouldUpdateTheStateToRunning() { @Test void addPineappleToppingToPizzaTest() { @Test void pineappleIsAnIllegalTopping_andShouldPreventTheCookFromAddingIt() {
35. To document is to communicate clearly Embrace magic numbers
36. var vatAmount = vatCalculator.getVatAmount(Percentage.valueOf(VAT_PERCENTAGE), Amount.eur(GROSS_PRICE)); assertThat(vatAmount).isEqualTo(Amount.eur(EXPECTED_AMOUNT)) Test that does not communicate or documents clearly
37. var vatAmount = vatCalculator.getVatAmount(Percentage.valueOf(21), Amount.eur(242)); assertThat(vatAmount).isEqualTo(Amount.eur(42)) Let your test document the full story avoiding layers or abstractions
38. @Test void shouldDetectValidIds() { Map<String, Object> fields = FieldsGenerator.withValidIds(); Map<String, Identifier> resolvedIdentifiers = resolver.resolve(fields); assertThat(resolvedIdentifiers).containsKey("TIN"); } Let your test document the full story avoiding layers or abstractions
39. @ParameterizedTest @ValueSource(strings = {"TIN", "LID", "PID"}) void shouldResolveValidIds(String validId) { var fields = Map.of( validId, "586-547-145", "SSN", "6589-8745-1547" ) Map<String, Identifier> resolvedIdentifiers = resolver.resolve(fields); assertThat(resolvedIdentifiers).containsKey(validId); } Let your test document the full story avoiding layers or abstractions
40. Address billingAddress = new Address.Builder() .streetAddress("123 Main St") .city("Anytown") .state("CA") .zipCode("12345") .country(Country.US) .build(); Address shippingAddress = new Address.Builder() .streetAddress("456 Oak Ave") .city("Othertown") .state("CA") .zipCode("67890") .country(Country.US) .build(); List<InvoiceItem> items = new ArrayList<>(); items.add(new InvoiceItem("Product A", 100.00, Tax.vatPercentage(21))); items.add(new InvoiceItem("Product B", 100.00, Tax.vatPercentage(21))); Customer customer = new Customer.Builder() .name("John Doe") .email("john.doe@example.com") .phoneNumber("555-123-4567") .build(); Invoice invoice = new Invoice.Builder() .invoiceNumber("001") .customer(customer) .billingAddress(billingAddress) .shippingAddress(shippingAddress) .invoiceDate(LocalDate.now()) .items(items) .build(); var amount = invoice.getVatAmount(); assertThat(amount).isEqualTo(Amount.EUR(42))
41. Given When Then Arrange Act Assert
42. // given Address billingAddress = new Address.Builder() .streetAddress("123 Main St") .city("Anytown") .state("CA") .zipCode("12345") .country(Country.USA) .build(); Address shippingAddress = new Address.Builder() .streetAddress("456 Oak Ave") .city("Othertown") .state("CA") .zipCode("67890") .country(Country.USA) .build(); List<InvoiceItem> items = new ArrayList<>(); items.add(new InvoiceItem("Product A", 100.00, Tax.vatPercentage(21))); items.add(new InvoiceItem("Product B", 100.00, Tax.vatPercentage(21))); Customer customer = new Customer.Builder() .name("John Doe") .email("john.doe@example.com") .phoneNumber("555-123-4567") .build(); Invoice invoice = new Invoice.Builder() .invoiceNumber("001") .customer(customer) .billingAddress(billingAddress) .shippingAddress(shippingAddress) .invoiceDate(LocalDate.now()) .items(items) .build(); // when var amount = invoice.getVatAmount(); // then assertThat(amount).isEqualTo(Amount.EUR(42))
43. Object Mother
44. InvoiceMother.validInvoice(); InvoiceMother.validInvoiceWithUSShippingAddress(); InvoiceMother.validInvoiceFromYesterday(); InvoiceMother.validInvoiceWithInvoiceLines(10); InvoiceMother.validInvoice() <InvoiceMother.Builder> .withInvoiceItems( new InvoiceItem("Product A", Amount.EUR(100), Tax.vatPercentage(21)), new InvoiceItem("Product B", Amount.EUR(100), Tax.vatPercentage(21))) .build(); <Invoice> Limit your factory methods, override what matters with setters InvoiceMother.validInvoice() .withShippingAddress(address -> address.country(Country.US)) .build() Emphasize what matters and hide the irrelevant details
45. //given var invoice = InvoiceMother.validInvoice() .withInvoiceItems( new InvoiceItem("Product A", Amount.EUR(100), Tax.vatPercentage(21)), new InvoiceItem("Product B", Amount.EUR(100), Tax.vatPercentage(21))) .build(); // when var amount = invoice.getVatAmount(); // then assertThat(amount).isEqualTo(Amount.EUR(42)) Emphasize what matters and hide the irrelevant details
46. Consider informative assertion messages.
47. org.opentest4j.AssertionFailedError: Expecting value to be true but was false Expected :true Actual :false assertThat(invoice.isPaid()).isTrue();
48. org.opentest4j.AssertionFailedError: Expecting invoice to be paid but was not. Expected :true Actual :false Assertions.assertThat(actual.isPaid()) .withFailMessage("Expecting invoice to be paid but was not.") .isTrue();
49. assertThat(invoice).isPaid();
50. class InvoiceAssertions extends AbstractAssert<InvoiceAssertions, Invoice> { protected InvoiceAssertions(Invoice invoice) { super(invoice, InvoiceAssertions.class); } public static InvoiceAssertions assertThat(Invoice invoice) { return new InvoiceAssertions(invoice); } public InvoiceAssertions isPaid() { Assertions.assertThat(actual.isPaid()) .withFailMessage("Expecting invoice to be paid but was not.") .isTrue(); return this; } }
51. //given InvoiceMother.validInvoice() .withInvoiceItems( new InvoiceItem("Product A", Amount.euro(100.00), Tax.vatPercentage(21)), new InvoiceItem("Product B", Amount.euro(100.00), Tax.vatPercentage(21))) .build(); // when var amount = invoice.getVATAmount(); // then assertThat(invoice).hasAVatAmountOf(Amount.euro(42.00))
52. Test and production code should be equal citizens looked at from different context with equal architectural rights cared for equally equally important
53. Let requirements drive tests minimize testing implementation details
54. 54 Jonas Geiregat Thanks for listening @jonas_grgt