TDD, BDD, ATDD are all methodologies that enable incremental design that is suitable for Agile environments. It seems that every day a new xDD methodology is born with the promise to be better than what came before. Should you use behaviour-driven tests or plain old unit tests? Which methodology is better? And how exactly would it benefit the development life cycle? In this session, Dror will help to sort out the various methodologies – explaining where they came from, the tools they use, and discussing how and when to use each one. Here we will once and for all answer the question as to whether or not there’s one “DD” to rule them all.

2. http://blog.drorhelper.com

3. A history lesson Methodologies
Books! Books!
Books!
Tools overview

6. little a few flaws
lot many more flaws
feature works
customer's requirements

7. 1991 1994 1997 2000 2002
Taligent
framework
NUnit 2.0Kent Beck
writes first
version of
SUnit test
framework*
Kent Beck &
Erich Gamma
create JUnit
During a flight
to OOPSLA
Michael
Features
ports JUnit to
C++ (CppUnit)

8. Test Suite
Fixture
Test Case
Test Case
Test Case
Test Case
Test Case
Fixture
Test Case
Test Case
Fixture
Test Case
Test Case
Test Case
public class BeforeAndAfter {
@Before
public void setUp() {
}
@After
public void tearDown() {
}
@Test
public void test1() {
}
@Test
public void test2() {
}
}

9. method
specific functionality,
clear pass/fail
runs in isolation

10. feedback
stupid
regression
without fear
documentation

12. Red
Green
Refactor

13. is not

14. @Test
public void Pass1_ReturnI() {
cut = new ArabicToRoman();
}

15. @Test
public void Pass1_ReturnI() {
cut = new ArabicToRoman();
}
public class ArabicToRoman {
}

16. @Test
public void Pass1_ReturnI() {
cut = new ArabicToRoman();
String result = cut.convert(1);
assertEquals("I", result);
}
public class ArabicToRoman {
}

17. @Test
public void Pass1_ReturnI() {
cut = new ArabicToRoman();
String result = cut.convert(1);
assertEquals("I", result);
}
public class ArabicToRoman {
public String convert(int num) {
return null;
}
}

18. @Test
public void Pass1_ReturnI() {
cut = new ArabicToRoman();
String result = cut.convert(1);
assertEquals("I", result);
}
public class ArabicToRoman {
public String convert(int num) {
return null;
}
}

19. @Test
public void Pass1_ReturnI() {
cut = new ArabicToRoman();
String result = cut.convert(1);
assertEquals("I", result);
}
public class ArabicToRoman {
public String convert(int num) {
return “I”;
}
}

20. @Test
public void Pass1_ReturnI() {
cut = new ArabicToRoman();
String result = cut.convert(1);
assertEquals("I", result);
}
public class ArabicToRoman {
public String convert(int num) {
return “I”;
}
}

21. @Test
public void Pass1_ReturnI() {
cut = new ArabicToRoman();
String result = cut.convert(1);
assertEquals("I", result);
}
@Test
public void Pass2_ReturnII() {
cut = new ArabicToRoman();
String result = cut.convert(2);
assertEquals("II", result);
}
public class ArabicToRoman {
public String convert(int num) {
return “I”;
}
}

22. @Test
public void Pass1_ReturnI() {
cut = new ArabicToRoman();
String result = cut.convert(1);
assertEquals("I", result);
}
@Test
public void Pass2_ReturnII() {
cut = new ArabicToRoman();
String result = cut.convert(2);
assertEquals("II", result);
}
public class ArabicToRoman {
public String convert(int num) {
return “I”;
}
}

23. @Test
public void Pass1_ReturnI() {
cut = new ArabicToRoman();
String result = cut.convert(1);
assertEquals("I", result);
}
@Test
public void Pass2_ReturnII() {
cut = new ArabicToRoman();
String result = cut.convert(2);
assertEquals("II", result);
}
public class ArabicToRoman {
public String convert(int num) {
if(i == 2)
return "II";
return "I";
}
}

24. @Test
public void Pass1_ReturnI() {
cut = new ArabicToRoman();
String result = cut.convert(1);
assertEquals("I", result);
}
@Test
public void Pass2_ReturnII() {
cut = new ArabicToRoman();
String result = cut.convert(2);
assertEquals("II", result);
}
public class ArabicToRoman {
public String convert(int num) {
if(i == 2)
return "II";
return "I";
}
}

25. @Test
public void Pass1_ReturnI() {
cut = new ArabicToRoman();
String result = cut.convert(1);
assertEquals("I", result);
}
@Test
public void Pass2_ReturnII() {
cut = new ArabicToRoman();
String result = cut.convert(2);
assertEquals("II", result);
}
public class ArabicToRoman {
public String convert(int num) {
result = new StringBuilder();
for(int i = 0 ; i < num ; i++)
{
result.append("I");
}
return result.toString();
}
}

28. S.Else Server
Call
CommClient Phone
RingMessage
OnCallRequested
AmazingUIAmazing UI
S Calling U
Accept Call
ConnectToServer
ConnectMessage

30. Server Comm Client UITestFake Comm

35. “
”
implementing
what you think the users want

37. 1996 2002 2002 2003
Automated tests
are part of Extreme
Programming.
Ward Cunningham
publishes Fit
Bob Martin
combines Fit with
Wikis tocreate
Fitnesse
Kent Beck briefly
mentions ATDD in
“TDD: By Example”
but dismisses it as
impractical

38. user story
development team implementation phase.

40. Unit tests Acceptance tests
Fast Slow
No side effects Side effects
Simple to run Dependent on environment
Test single “unit of work” Test single scenario/feature
Written by developers Written by customers
Verify that code works Overall system works as required
Test must pass before check-in Test may only pass when feature is
done
Fake other units Fake other systems

42. numerator Denominator quotient?
10 2 5.0
12.6 3 4.2
100 4 33
org/FitNesse.FullReferenceGuide.UserGuide.WritingAcceptanceTests.FixtureCode
public class Division {
private double numerator,
denominator;
public void setNumerator(double
numerator) {
this.numerator = numerator;
}
public void setDenominator(double
denominator) {
this.denominator = denominator;
}
public double quotient() {
return numerator/denominator;
}
}

44. Red
Green
Refactor
Red
Green
Refactor Red
Green
RefactorRed
Green
Refactor
Red
Green
Refactor Red
Green
Refactor
Red
Green
Refactor

45. Discuss
DistillDevelop
Demo
ed.com/wp-content/uploads/2011/04/atddexample.pdf
Story
item
Red
Green
Refactor
TDD

47. “
”
Specifications are supposed to be general
Examples only highlight a few points
http://martinfowler.com/bliki/SpecificationByExample.html

48. /drawings/d/1cbfKq-KazcbMVCnRfih6zMSDBdtf90KviV7l2oxGyWM/edit?hl=en
Business goal/desired effect
Scope
Key Examples
Specification with Examples
Executable Specification
Living Documentation
Derive the scope from goals
Specify collaboratively
Refine the specification
Validate frequently
Automate literally

52. Sensors PLC ModelClient
Business
logic
Raw data
Converted
data
command

54. less of a wax-on, wax-off process of
gradual mastery than a series of blind alleys…
presentTDD in a way
that gets straight to the good stuff and avoids all the
pitfalls.

55. public class CustomerLookupTest extendsTestCase {
testFindsCustomerById() {
}
testFailsForDuplicateCustomers() {
}
}

56. × Test123
× CustomerTest
× PerchaseOrderTestNew
× MoveBatteryVanilla
 CalculateTax_InvalidYear_LogErrorToFile
 OrdersShouldBeCreated
 OrdersWithNoProductsShouldFail

57. “
”
comprehensively
describe the behaviour of your system
“Behaviour” is a more useful word than “test”

59. Steps
Scenarios
Story
In Order to…
As a…
I want to…
Scenario 1
Given When Then
Scenario 2
Given When Then

60. public class TraderSteps{
private TradingService service;
private Stock stock;
@Given("a stock and a threshold of $threshold")
public void aStock(double threshold) {
stock = service.newStock("STK", threshold);
}
@When("the stock is traded at price $price")
public void theStockIsTraded(double price){
stock.tradeAt(price);
}
@Then("the alert status is $status")
public void theAlertStatusIs($status){
assertThat(stock.getStatus().Name(), equalTo(status));
}
}
Scenario: A trader is alerted of status
Given a stock and a threshold of 15.0
When stock is traded at 5.0
Then the alert status should be off

61. Feature: Addition
In order to avoid silly mistakes
As a math idiot
I want to be told the sum of two numbers
Scenario: Add two numbers
Given I have entered 50 into the calculator
And I have entered 70 into the calculator
When I press add
Then the result should be 120 on the screen
From: https://cukes.info/

62. describe Stack do
it "should return a blank instance" do
Stack.new.should == {}
end
it "element is added to the stack on top of the stack" do
stack = Stack.new
stack.push 'a value'
stack.pop.should == 'a value'
end
end
Stack
should return a blank instance
element is added to the stack on top of the stack

64. [Test]
public void OutOfStorageWhileCreatingFileAndExactFilesToMakeRoom()
{
var fakeSystemInfo = A.Fake<ISystemInfo>();
A.CallTo(() => fakeSystemInfo.GetFreeDiskSpaceInBytes()).Returns(0);
var logfiles = new[]
{
new LogFile
{
Name = "file-1.log",
Size = 50000
},
new LogFile
{
Name = "file-2.log",
Size = 50000
}
};
var fakeLogFolder = A.Fake<ISharedStorageFolder>();
A.CallTo(() => fakeLogFolder.GetFiles()).Returns(logfiles);
var logFileWriter = new LogFileWriter(fakeSystemInfo, fakeLogFolder);
logFileWriter.Write("some message");
A.CallTo(() => fakeLogFolder.DeleteFile("file-1.log")).MustHaveHappened();
A.CallTo(() => fakeLogFolder.DeleteFile("file-2.log")).MustHaveHappened();
}

65. SCENARIO("First roll is strike")
{
GIVEN("Bowled strike on first turn")
{
Game game;
game.Roll(10);
WHEN("Next roll is spare then roll five")
{
game.Roll(3);
game.Roll(7);
game.Roll(5);
RollSeveral(game, 15, 0);
THEN("Total score is 40")
{
REQUIRE(game.Score() == 40);
}
}
WHEN("Next two rolls are strike then gutter balls")
{
game.Roll(10);
game.Roll(10);
RollSeveral(game, 16, 0);
THEN("Total score is 60")
{
REQUIRE(game.Score() == 60);
}
}
}
}

67. TDD
Classic
London
ATDD
SbE
BDD
Stories
Specification

68. Choose 2

69. “
”http://lizkeogh.com/2011/03/04/step-away-from-the-tools/

70. http://geek-and-poke.com/geekandpoke/2013/6/6/dont-ask-your-boss

71. “
”http://blog.mattwynne.net/2012/11/20/tdd-vs-bdd/

72. They're just both useful to have in your back
pocket as you go around trying to write decent
software to solve useful problems.
But I bet
that's what Kent Beck would say if you asked him
whatTDD was all about.
Dan North, DefiningTDD,
https://groups.google.com/forum/#!msg/behaviordrivendevelopment/OQnb3APpUJk/RklRiyEKde4J

73. Thank you
drorh@codevalue.net
http://blog.drorhelper.com