Avatars of Test Driven Development (TDD)

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Copyright © 2013, AgileFAQs. All Rights Reserved. Avatars of TDD Rule of Diversity Distrust all claims for “One True Way” Naresh Jain [email protected] @nashjain http://nareshjain.com

description

It's easy to speak of test-driven development as if it were a single method, but there are several ways to approach it. In my experience, different approaches lead to quite different solutions. In this hands-on workshop, with the help of some concrete examples, I'll demonstrate the different styles and more importantly what goes into the moment of decision when a test is written? And why TDDers make certain choices. The objective of the session is not to decide which approach is best, rather to highlight various different approaches/styles of practicing test-driven development. By the end of this session, you will understand how TTDers break down a problem before trying to solve it. Also you'll be exposed to various strategies or techniques used by TDDers to help them write the first few tests.

Transcript of Avatars of Test Driven Development (TDD)

Page 1: Avatars of Test Driven Development (TDD)

Copyright © 2013, AgileFAQs. All Rights Reserved.

Avatars of TDDRule of Diversity

Distrust all claims for “One True Way”

Naresh [email protected]

@nashjain http://nareshjain.com

Page 2: Avatars of Test Driven Development (TDD)

Copyright © 2013, AgileFAQs. All Rights Reserved.

Key Questions

Are we building the right product?

Are we building the product right?

Business Facing

Technology/Implementation Facing

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Copyright © 2013, AgileFAQs. All Rights Reserved.

Brian Marick’s Test Categorization

Business Facing

Technology/Implementation Facing

Supp

orts

Pro

gram

min

gC

ritique product

Before/While Coding Post Coding

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Copyright © 2013, AgileFAQs. All Rights Reserved.

It Helps to Think of Tests this way...

Business Facing

Technology/Implementation Facing

Dri

ves

Dev

elop

men

t Critique productUnit Testing

Acceptance Testing Low-fi prototypes

Exploratory TestingUI and Usability Testing

Performance TestingSystem Tests

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Business Facing

Technology/Implementation Facing

Dri

ves

Dev

elop

men

t Critique product

Outside In

Inside Out

Brian Marick’s Test Categorization

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Add a Test

Run the Test

Make a little change

Run the Test

Refactor

Fail

Pass

Fail

Pass

TDD RhythmTest, Code, Refactor

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Acceptance Test Driven Development

Iteration

Automated Acceptance Tests

AutomatedAcceptance Tests

Story

Acceptance Criteria

Acceptance Criteria

ExploratoryTesting

Automated UI Tests

TESTS

PERFORMENCE

Automated Unit Test

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Commercial Break!

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Tech Talks!

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Page 13: Avatars of Test Driven Development (TDD)

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Veterinarian Information System

It all started with...

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Outside In: ATDDFitnesse Document:Assertions: 17 right, 0 wrong, 0 ignored, 0 exceptions

com.vis.billing.fixtures.PaidCashBill

account details

account number patient name owner name

1001 Fluffy Dave Atkins

procedure detailsname cost

Routine Office Visit 250

Rabies Vaccination 50

bill

account number? owner name? patient name? total? paid?

1001 Dave Atkins Fluffy 300 false

procedure details on the bill

name cost

Routine Office Visit 250

Rabies Vaccination 50

pay Cash

patient name? owner name? account number? bill no? payment method? amount paid?

Fluffy Dave Atkins 1001 1 Cash 300

check paid true

check total 0

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Outside In: Output

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ATDD: Another ExampleAcceptance 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 endend

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Outside In: Output

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Inside Out: Unit TDDpublic class ClinicTest { private Clinic clinic = new Clinic();

@Test public void amountOnTheReceiptShouldMatchBillableAmount() throws Exception { Billable billable = new Billable() { public int totalAmount() { return 0; } }; Account dave = new Account(101, "Dave");

Receipt rcpt = clinic.payCash(dave, billable); assertEquals("Amount on receipt does match procedure cost", billable.totalAmount(), rcpt.getAmount()); }

@Test public void customerPayesBillableAmountForCashTransaction() throws Exception { final int billableAmount = 56; class AmountCharged { int charged; }; final AmountCharged charged = new AmountCharged();

Billable billable = new Billable() { public int totalAmount() { return billableAmount; } };

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); }}

public class BillableTest {

private static final Account daveSAccount = new Account(101, "Dave"); private static final List<Service> services = new ArrayList<Service>();

@Test public void totalBillableAmountShouldBeZeroIfNoServicesAreProvided() { Billable bill = new Bill(daveSAccount, services); assertEquals("Total amount is not Zero", 0, bill.totalAmount()); }

@Test public void totalBillableAmountShouldBeTotalOfEachServiceProvided() { services.add(new Procedure("Rabies Vaccination", 250)); services.add(new Procedure("Regular office Visit", 50));

Billable bill = new Bill(daveSAccount, services);

assertEquals("Total Amount is not 300", 300, bill.totalAmount()); }

@After public void cleanUp() { services.clear(); }}

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Inside Out: Output

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Inside Out: Another Examplepublic class ChargeAccountForServices { private static final Billable bill = createMock(Billable.class); private static final Accountable account = createMock(Accountable.class); private static final Clinic clinic = new Clinic();

@Before public void setUp() { reset(account); reset(bill); }

@Test public void shouldMakePaymentsAgainstAnAccount() { account.paid(bill); replay(account); clinic.pay(300, bill, account); verify(account); }

@Test public void shouldHaveZeroAmountDueOnReceiptIfCompletePaymentIsMade() { expect(bill.amount()).andReturn(300); replay(bill); Receipt receipt = clinic.pay(300, bill, account); verify(bill); assertEquals(300, receipt.amount()); assertEquals(0, receipt.amountDue()); }

@Test public void shouldDisplayAmountDueOnTheReceiptIfIncompletePaymentIsMade() { expect(bill.amount()).andReturn(500); replay(bill); Receipt receipt = clinic.pay(300, bill, account); verify(bill); assertEquals(300, receipt.amount()); assertEquals(200, receipt.amountDue()); }}

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public class CreateBillForClientAccount { private static final List<Service> services = new ArrayList<Service>(); private static final Accountable account = createMock(Accountable.class); private Bill bill;

@Before public void setUp() { reset(account); }

@Test public void shouldThrowExceptionIfAccountIsNotDueForPayment() { expect(account.isPaymentDue()).andReturn(false); replay(account); try { new Bill(account, null); } catch (NoPaymentDueException e) { // expected } verify(account); }

@After public void cleanUp() { services.clear(); }

@Test public void shouldCreateABillWithTheTotalCostOfAllTheServices() { IMocksControl control = createControl(); Service rabiesVaccination = control.createMock(Service.class); Service routineVisit = control.createMock(Service.class); services.add(rabiesVaccination); services.add(routineVisit);

expect(account.isPaymentDue()).andReturn(true); expect(account.unpaidServices()).andReturn(services); bill();

expect(rabiesVaccination.cost()).andReturn(250); expect(routineVisit.cost()).andReturn(50);

control.replay();

assertEquals(300, bill.amount()); control.verify(); }

private void bill() throws NoPaymentDueException { replay(account); bill = new Bill(account, null); verify(account); }}

Inside Out: Example Continued...

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Inside Out: Output

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Copyright © 2013, AgileFAQs. All Rights Reserved.

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

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Bonus Calculator

Sales Quota Commission % Tax % Result1200 1100 10 10 91200 1500 10 10 01200 1200 10 10 0

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First Few Tests Inside-Out Tests @Test! public void noBonusForLowPerformers() {! ! whenSalesIs(0).andQuotaIs(100).thenIndividualBonusIs(0);! }

! @Test! public void noBonusForAveragePerformers() {! ! whenSalesIs(100).andQuotaIs(100).thenIndividualBonusIs(0);! }

! @Test! public void bonusIsBasedOnCommissionPercentage() {! ! whenSalesIs(110).andQuotaIs(10).andCommissionIs(100).thenIndividualBonusIs(100);! ! whenSalesIs(110).andQuotaIs(10).andCommissionIs(10).thenIndividualBonusIs(10);! }

! @Test! public void bonusIsBasedOnCommissionPercentageAfterTax() {! ! whenSalesIs(110).andQuotaIs(10).andCommissionIs(100).andTaxIs(10).thenIndividualBonusIs(90);! ! whenSalesIs(110.02).andQuotaIs(10.01).andCommissionIs(10).andTaxIs(10).thenIndividualBonusIs(9);! }

Page 27: Avatars of Test Driven Development (TDD)

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Sales TaxBasic sales tax is applicable at a rate of 10% on all goods, except books, food, and medical products that are exempt. Import duty is an additional sales tax applicable on all imported goods at a rate of 5%, with no exemptions.

When I purchase items I receive a receipt which lists the name of all the items and their price (including tax), finishing with the total cost of the items, and the total amounts of sales taxes paid.

Write an application that prints out the receipt details for these shopping baskets...

Input 1:1 book at 12.491 music CD at 14.991 chocolate bar at 0.85

Output 1:1 book : 12.491 music CD: 16.491 chocolate bar: 0.85Sales Taxes: 1.50Total: 29.83

Input 2:1 imported box of chocolates at 10.001 imported bottle of perfume at 47.50

Output 2:1 imported box of chocolates: 10.501 imported bottle of perfume: 54.65Sales Taxes: 7.65Total: 65.15

Input 3:1 imported bottle of perfume at 27.991 bottle of perfume at 18.991 packet of headache pills at 9.751 box of imported chocolates at 11.25

Output 3:1 imported bottle of perfume: 32.191 bottle of perfume: 20.891 packet of headache pills: 9.751 imported box of chocolates: 11.85Sales Taxes: 6.70Total: 74.68

Page 28: Avatars of Test Driven Development (TDD)

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First Few Outside-In Tests@Testpublic void checkOutEmptyCart() { assertTotalIs(0);}

@Testpublic void checkOutAnExemptedDomesticItem() { cart.add(rs100DomesticBook); assertTotalIs(100);}

@Testpublic void checkOutTaxableDomesticItem() { cart.add(rs100DomesticMusicCD); assertTotalIs(110);}

@Testpublic void checkOutExemptedImportedItem() { cart.add(rs100ImportedBook); assertTotalIs(105);}

@Testpublic void checkOutImportedItem() { cart.add(rs100ImportedMacBook); assertTotalIs(115);}

Page 29: Avatars of Test Driven Development (TDD)

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Medical System Age Calculating ProgramAge Reported in

Greater than 1 Year <Patient Name> is # Years old

> 1 Month & < 1 Year <Patient Name> is # Months old

> 1 Day & < 1 Month <Patient Name> is # Days old

> 1 Hr & < 1 Day <Patient Name> is # Hours old

Doctors and Nurses might like to add and remove new Durations.For Ex: If they add Decade, and Patient’s age is greater than 10 years, then age should be reported as <Patient Name> is # Decades old.

Similarly: If they add Week, and Patient’s age is greater than 7 Day, but less than a month, then age should be reported as <Patient Name> is # Weeks old.

Page 30: Avatars of Test Driven Development (TDD)

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First Few Inside-Out Tests@RunWith(Parameterized.class)public class DurationTest extends FixedTimeTestCase {! private final Date date;! private final String result;

! public DurationTest(Object date, Object result) {! ! this.date = (Date) date;! ! this.result = (String) result;! }

! @Parameters! public static List<Object[]> data() {! ! return new ArrayList<Object[]>() {! ! ! {! ! ! ! add(new Object[] { may3rd1980, "31 Years" });! ! ! ! add(new Object[] { jan1st2011, "9 Months" });! ! ! ! add(new Object[] { oct1st2011, "10 Days" });! ! ! ! add(new Object[] { oct11nth2011Afternoon, "0 Hours" });! ! ! }! ! };! }

! @Test! public void calculatesDurationSince() {! ! String value = Duration.since(date);! ! assertEquals("For " + date, result, value);! }

! @Override! protected Date currentTime() {! ! return oct11nth2011Afternoon;! }}

@Testpublic void canRegisterAndUnregisterLargestDuration() { assertEquals("31 Years", Duration.since(may3rd1980));

Duration.register("Decades", MILLISECONDS_PER_YEAR * 10); assertEquals("3 Decades", Duration.since(may3rd1980));

Duration.unregister("Decades"); assertEquals("31 Years", Duration.since(may3rd1980));}

@Testpublic void canRegisterAndUnregisterSmallestDuration() { assertEquals("0 Hours", Duration.since(oct11nth2011Morning));

Duration.register("Minutes", MILLISECONDS_PER_MINUTE); assertEquals("2 Minutes", Duration.since(oct11nth2011Morning));

Duration.unregister("Minutes"); assertEquals("0 Hours", Duration.since(oct11nth2011Morning));}

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Meeting Assistant

Page 32: Avatars of Test Driven Development (TDD)

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First Few Outside-In Tests

@Testpublic void jackWantsThinkingTime() { jack().isAvailable(now).forEver(); firstAvailableSlotFor(THIRTY_MINS).is(now);}

@Testpublic void jackBusyForNextTwoHours() { jack().isAvailable(inTwoHours).forEver(); firstAvailableSlotFor(THIRTY_MINS).is(inTwoHours);}

@Testpublic void jackAndJillAreAvailableRightNowToMeet() { jack().isAvailable(now).forEver(); jill().isAvailable(now).forEver(); between(JACK, JILL).firstAvailableSlotFor(THIRTY_MINS).is(now);}

@Testpublic void jackIsAvailableLaterForARequiredDuration() { jack().isAvailable(now).forNext(TWENTY_MINS); jack().isAvailable(inTwoHours).forEver(); firstAvailableSlotFor(THIRTY_MINS).is(inTwoHours);}

@Test(expected = RuntimeException.class)public void jackHasNoTimeToThink() { jack().isNotAvailable(); assistant.firstAvailableTimeFor(participants, THIRTY_MINS);}

Page 33: Avatars of Test Driven Development (TDD)

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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

Page 34: Avatars of Test Driven Development (TDD)

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Thank you

Naresh [email protected]