Avatars Of TDD

Avatars of TDD Rule of Diversity Distrust all claims for “One True Way” Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 1

Overview TDD Rhythm - Test, Code, Refactor Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 2

Overview Add a Test TDD Rhythm - Test, Code, Refactor Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 2

Overview Add a Test Run the Test TDD Rhythm - Test, Code, Refactor Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 2

Overview Add a Test Pass Run the Test TDD Rhythm - Test, Code, Refactor Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 2

Overview Add a Test Pass Run the Test Fail TDD Rhythm - Test, Code, Refactor Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 2

Overview Add a Test Pass Run the Test Fail TDD Rhythm - Test, Code, Refactor Make a little change Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 2

Overview Add a Test Pass Run the Test Fail TDD Rhythm - Test, Code, Refactor Make a little change Run the Test Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 2

Overview Add a Test Pass Run the Test Fail TDD Rhythm - Test, Code, Refactor Make a little change Fail Run the Test Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 2

Overview Add a Test Pass Run the Test Fail TDD Rhythm - Test, Code, Refactor Make a little change Fail Run the Test Pass Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 2

Overview Add a Test Pass Run the Test Fail TDD Rhythm - Test, Code, Refactor Make a little change Fail Run the Test Pass Refactor Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 2

Simple easy to understand, deal with, use, etc.: a simple matter; simple tools. not elaborate or artiﬁcial; plain: a simple style. not ornate or luxurious; unadorned: a simple gown. unaffected; unassuming; modest: a simple manner. not complicated: a simple design. not complex or compound; single. occurring or considered alone; mere; bare: the simple truth; a simple fact. free of deceit or guile; sincere; unconditional: a frank, simple answer. common or ordinary: a simple soldier. not grand or sophisticated; unpretentious: a simple way of life. humble or lowly: simple folk. inconsequential or rudimentary. Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 3

What is Simple Design? A design that allows you to keep moving forward with least amount of resistance Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 4

Embrace Simple Design Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 5

Simple Design? easy to understand, deal with: communicates its intent. not elaborate or artiﬁcial; plain: crisp and concise not ornate or luxurious; unadorned: minimalistic; least possible components (classes and methods). unaffected; unassuming; modest: does not have unanticipated side-effects. not complicated: avoids unnecessary conditional logic. not complex or compound; single: just does one thing and does it well. occurring or considered alone; mere; bare: to the point. Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 6

Simple Design? ... free of deceit or guile; sincere; unconditional: abstracts implementation from intent, but does not deceive someone by concealing or misrepresenting the actual concept. common or ordinary: built on standard patterns which are well understood. not grand or sophisticated; unpretentious: fulﬁlls today’s needs without unnecessary bells and whistles (over-engineering). humble or lowly. inconsequential or rudimentary: does not draw your attention to unnecessary details; achieves good abstractions Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 7

Summary Do the Simplest thing that could possibly work YAGNI Design Patterns. Code Smells (Code Screams) Unix Programming Philosophy OO Design principles - SOLID, DRY, TDA Functional Programming - Immutability and Side effect free Simple Design and TDD go hand in hand Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 8

Why bother about TDD? Confident & Feedback Design & Code minimalistic and clean Decoupling and Testable Safety net of executable, living, up-to-date specification Learning by listening to your code Slow down and think Communicate my design choices Efficient: Debugging and Manual Testing Maintain focus Reduce Wastage: Hand-overs Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 9

Before you take the plunge... Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 10

Before you take the plunge... System Metaphor Election Metaphor ‘Google Search Engine’ Metaphor Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 10

Before you take the plunge... System Metaphor Election Metaphor ‘Google Search Engine’ Metaphor Thin Slice ProTest - Dependency Voter Proﬁle Picture Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 10

Before you take the plunge... System Metaphor Election Metaphor ‘Google Search Engine’ Metaphor Thin Slice ProTest - Dependency Voter Proﬁle Picture Interaction Design Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 10

Before you take the plunge... System Metaphor Election Metaphor ‘Google Search Engine’ Metaphor Thin Slice ProTest - Dependency Voter Proﬁle Picture Interaction Design Tracer Bullets: Prototyping, a forgotten Design Practice Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 10

Before you take the plunge... Micro-Design v/s Macro-Design v/s BUFD Unit Tests Validates Micro-Design There is No Spoon Fluent Interfaces in Test Behavior (verbs) as Test Class Names Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 11

There is no Spoon Veterinarian Information System (system responsible for billing & patient history) ChargeAccountForServices with the following test methods: makePaymentsAgainstAnAccount() completePaymentsResultInZeroAmountDueOnReceipt() incompletePaymentsDisplaysDueAmountOnTheReceipt() Another test class: GenerateBillsForClientAccount with notifyIfAccountIsNotDueForPayment() billContainsTotalCostOfAllServicesTaken() And another test class: ManageClientVisits with trackAllServicesTakenByThePatient() skipVisitIfPatientDidNotTakeAnyService() Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 12

Other Test Naming Convention Other’s Naming Convention My Naming Convention itShouldSetAccountToLoggedInWhenPasswordMatches matchingPasswordLogsYouIn itShouldSetAccountToRevokedAfterThreeFailedLoginAttempts threeFailedLoginAttemptsRevokesYourAccount itShouldNotSetAccountLoggedInIfPasswordDoesNotMatch nonMatchingPasswordDoesNotLogYouIn itShouldNotRevokeSecondAccountAfterTwoFailedAttemptsFirst failedLoginAttemptsOnOtherAccountsDoesNotImpact Account MyAccount itShouldNowAllowConcurrentLogins sameUserCannotLoginConcurrently itShouldThrowExceptionIfAccountNotFound onlyUserWithExistingAccountCanLogin ItShouldNotBePossibleToLogIntoRevokedAccount userWithRevokedAccountCannotLogin itShouldResetBackToInitialStateAfterSuccessfulLogin successfulLoginResetsFailedAttemptCount Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 13

Fluent Interfaces Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 14

Fluent Interfaces @Test public void redirectDomainsWithSubDomainsPermanently() { server.redirect(“google.com”).withSubDomain().to(“directi.com”); client_requests(“blog.google.com”); response = domainForwardingServer.process(request); assertStatusIs(PermanentRedirect); assertLocationIs(“directi.com/blog”); assertStandardResponseHeaderIsPresent(); } Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 14

Fluent Interfaces @Test public void redirectDomainsWithSubDomainsPermanently() { server.redirect(“google.com”).withSubDomain().to(“directi.com”); client_requests(“blog.google.com”); response = domainForwardingServer.process(request); assertStatusIs(PermanentRedirect); assertLocationIs(“directi.com/blog”); assertStandardResponseHeaderIsPresent(); } User naresh_from_mumbai = new User("naresh", "jains", "mumbai", "india", "indian"); Context lets = new Context(userService, dns); IdentitySuggester suggester = new IdentitySuggester(userService, dns, randomNumberGenerator); @Test public void avoidCelebrityNamesInGeneratedIds() { lets.assume("naresh", "jain").isACelebrityName(); List<String> generatedIds = suggester.generateIdsFor(naresh_from_mumbai); lets.assertThat(generatedIds).are("nares@jain.com", "naresh@india.com"); } Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 14

Avatars of TDD Business Facing Drives Development Critique product Inside Out Outside In Technology/Implementation Facing Brian Marick’s Test Categorization Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 15

Outside In: ATDD Fitnesse Document: Assertions: 17 right, 0 wrong, 0 ignored, 0 exceptions com.vis.billing.fixtures.PaidCashBill procedure details on the bill account details name cost account number patient name owner name Routine Office Visit 250 1001 Fluffy Dave Atkins Rabies Vaccination 50 procedure details pay Cash name cost patient name? owner name? account number? bill no? payment method? amount paid? Routine Office Visit 250 Fluffy Dave Atkins 1001 1 Cash 300 Rabies Vaccination 50 bill check paid true account number? owner name? patient name? total? paid? 1001 Dave Atkins Fluffy 300 false check total 0 Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 16

Outside In: ATDD Output Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 17

ATDD: Another Example Acceptance test: class FluffyTest < Test::Unit::TestCase def test_examination_and_shots vet = Veterinarian.new clinic = Clinic.new "Main Line health" dave = Owner.new "Dave" fluffy = Patient.new "Fluffy" dave.has fluffy visit = clinic.visit(fluffy, vet) do |v| v.procedure "Rabies vaccination", 50 end invoice = visit.invoice assert_equal invoice.to_s, <<-INVOICE Routine visit: $200 Rabies vaccination: $50 Total: $250 INVOICE receipt = clinic.pay_for visit, 100 assert_equal receipt.to_s, <<-RECEIPT Paid $100 for Routine visit Paid $0 for Rabies vaccination Outstanding: $150 RECEIPT end Licensed Under Creative Commons by Naresh Jain end Friday, September 18, 2009 18

Output from ATDD Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 19

Inside Out: Unit TDD public class ClinicTest { private Clinic clinic = new Clinic(); public class BillableTest { @Test public void amountOnTheReceiptShouldMatchBillableAmount() throws Exception { private static final Account daveSAccount = new Account(101, "Dave"); Billable billable = new Billable() { private static final List<Service> services = new ArrayList<Service>(); public int totalAmount() { return 0; } }; @Test Account dave = new Account(101, "Dave"); public void totalBillableAmountShouldBeZeroIfNoServicesAreProvided() { Billable bill = new Bill(daveSAccount, services); Receipt rcpt = clinic.payCash(dave, billable); assertEquals("Total amount is not Zero", 0, bill.totalAmount()); assertEquals("Amount on receipt does match procedure cost", billable.totalAmount(), rcpt.getAmount()); } } @Test @Test public void totalBillableAmountShouldBeTotalOfEachServiceProvided() { public void customerPayesBillableAmountForCashTransaction() throws Exception { services.add(new Procedure("Rabies Vaccination", 250)); final int billableAmount = 56; services.add(new Procedure("Regular office Visit", 50)); class AmountCharged { int charged; }; final AmountCharged charged = new AmountCharged(); Billable bill = new Bill(daveSAccount, services); Billable billable = new Billable() { assertEquals("Total Amount is not 300", 300, bill.totalAmount()); public int totalAmount() { } return billableAmount; } @After }; public void cleanUp() { services.clear(); Account dave = new Account(101, "Dave") { } public void charge(int amount) { } charged.charged = amount; } }; clinic.payCash(dave, billable); assertEquals("Account is not charged billable amount", billableAmount,charged.charged); } } Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 20

Inside Out: Output Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 21

Inside Out: Another Example @Test public class ChargeAccountForServices { public void shouldHaveZeroAmountDueOnReceiptIfCompletePaymentIsMade() { private static final Billable bill = createMock(Billable.class); expect(bill.amount()).andReturn(300); private static final Accountable account = createMock(Accountable.class); replay(bill); private static final Clinic clinic = new Clinic(); Receipt receipt = clinic.pay(300, bill, account); verify(bill); @Before assertEquals(300, receipt.amount()); public void setUp() { assertEquals(0, receipt.amountDue()); reset(account); } reset(bill); } @Test public void shouldDisplayAmountDueOnTheReceiptIfIncompletePaymentIsMade() { @Test expect(bill.amount()).andReturn(500); public void shouldMakePaymentsAgainstAnAccount() throws Exception { replay(bill); account.paid(bill); Receipt receipt = clinic.pay(300, bill, account); replay(account); verify(bill); clinic.pay(300, bill, account); assertEquals(300, receipt.amount()); verify(account); assertEquals(200, receipt.amountDue()); } } } Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 22

public class CreateBillForClientAccount { @Test private static final List<Service> services = new ArrayList<Service>(); public void shouldCreateABillWithTheTotalCostOfAllTheServices() { private static final Accountable account = createMock(Accountable.class); IMocksControl control = createControl(); private Bill bill; Service rabiesVaccination = control.createMock(Service.class); Service routineVisit = control.createMock(Service.class); @Before services.add(rabiesVaccination); public void setUp() { services.add(routineVisit); reset(account); } expect(account.isPaymentDue()).andReturn(true); expect(account.unpaidServices()).andReturn(services); bill(); @Test public void shouldThrowExceptionIfAccountIsNotDueForPayment() { expect(rabiesVaccination.cost()).andReturn(250); expect(account.isPaymentDue()).andReturn(false); expect(routineVisit.cost()).andReturn(50); replay(account); try { control.replay(); new Bill(account, null); } catch (NoPaymentDueException e) { assertEquals(300, bill.amount()); // expected control.verify(); } } verify(account); } private void bill() throws NoPaymentDueException { replay(account); @After bill = new Bill(account, null); public void cleanUp() { verify(account); services.clear(); } } } Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 23

Inside Out: Output Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 24

Coffee Vending Machine How would you develop it? Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 25

Where do you Stand? Unit Test x Acceptance test API x User Interface State x Interaction OO x Procedural Easy x Core Narrow x Broad Drive Design x Validate Design Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 26

Thank you! naresh@agilefaqs.com http://blogs.agilefaqs.com/ Licensed Under Creative Commons by Naresh Jain Friday, September 18, 2009 27

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Avatars Of TDD

by Naresh Jain on Sep 18, 2009

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