TDD

1. INTRODUCTION TO
TEST DRIVEN
DEVELOPMENT
tw: @MaciejGrajcarek

2. Check List
1. History of TDD
2. TDD Cycles
3. BDD
4. TDD is dead?
5. PHPSpec

3. Who needs tests anyway?

4. Who needs tests anyway? Bugs
killers!

5. Technical Debt

6. Technical Debt

7. Where it all began
Waterfall Model
Winston W. Royce (1970)

8. Where it all began
Agile – best friend of TDD
- Adaptive vs Predictive
- Iterative vs Waterfall
2001 – Agile Manifesto

9. Where it all began
Scrum Cicle
Analysis
Programming
Testing
Acceptance

10. Where it all began
„Test Driven Development: By
Example” – Kent Beck (2003)

11. Check List
1. History of TDD
2. TDD Cycle of life
3. BDD
4. TDD is dead?
5. PHPSpec

12. TDD Cycle of life
Failing Test
Pass testRefactoring

13. TDD Cycle of life
Failing Test
•Make test
compile
•Make sure it
doesn’t pass

14. First simple failing test
function checkSumTest()
{
$a = 5;
$b = 4;
$calculator = new Calculator();
$sum = $calculator->sum($a, $b);
$this->assertEqual(9, $sum);
}

15. TDD Cycle of life
Pass test
• Fake It (Till You
Make It)
• Type The Obvious
Implementation
• Triangulation

16. Fake It (Till You Make It)
class Calculator
{
function sum($a, $b)
{
return 9;
}
}

17. Type The Obvious
Implementation
class Calculator
{
function sum($a, $b)
{
$sum = $a + $b;
return $sum;
}
}

18. Triangulation
At least two points needed to find a
location.

19. Triangulation
//Test 1
$sum = $calculator->sum($a, $b);
$this->assertEqual(9, $sum);
class Calculator
{
function sum($a, $b)
{
$sum = $a + $b;
return $sum;
}
}

20. Triangulation
//Test 1
$sum = $calculator->sum(4, 5);
$this->assertEqual(9, $sum);
//Test 2
$sum = $calculator->sum(4, 5, 7);
$this->assertEqual(16, $sum);
class Calculator
{
function sum($a, $b, $c = 0)
{
$sum = $a + $b + $c;
return $sum;
}
}

21. Triangulation
//Test 1
$sum = $calculator->sum(4, 5);
$this->assertEqual(9, $sum);
//Test 2
$sum = $calculator->sum(4, 5, 7);
$this->assertEqual(16, $sum);
//Test 3
$sum = $calculator->sum(4, 5, 7, 1);
$this->assertEqual(17, $sum);

22. Triangulation
class Calculator
{
function sum()
{
$elements = func_get_args();
$sum = 0;
foreach ($elements as $el) {
$sum += $el;
}
return $sum;
}
}

23. Triangulation
//Test 1
$sum = $calculator->sum(4, 5);
$this->assertEqual(9, $sum);
//Test 2
$sum = $calculator->sum(4, 5, 7);
$this->assertEqual(16, $sum);
//Test 3
$sum = $calculator->sum(4, 5, 7, 1);
$this->assertEqual(17, $sum);

24. Triangulation
//Final test
$sum = $calculator->sum(4, 5, 7, 1);
$this->assertEqual(17, $sum);

25. TDD Cycle of life
Refactoring
•KISS
•DRY

26. Maintainability, Flexibility, Portability, Reusability,
Readability, Scalability, Testability, Understandability

27. Don’t Repeat Yourself
1)
Extract
Shared
Concept
2) Give it
a name
3) Reuse
it
If impossible to do 1-2, there is no repetition

28. TDD Cycle of life
Failing Test
Pass testRefactoring

29. Check List
1. History of TDD
2. TDD Cycle of life
1. Red phase
2. Green phase
3. Refactoring
3. Tests measurement
4. TDD Tips
5. BDD
6. TDD is dead?
7. PHPSpec

30. Tests measurement
1. Code Coverage
2. Underlay Defects
- 100 % code coverage != Error Free
- Vendor code should have 100% code
coverage, but yours not necessarily

31. TDD Tips
1. Create a check list of tests

32. TDD Tips
1. Create a check list of tests
2. Small step approach during
refactorization (or larger when fealing
comfortable)

33. TDD Tips
1. Create a check list of tests
2. Small step approach during refactorization (or
larger when fealing comfortable)
3. Add problems to the list, instead of
resolving them immediately

34. TDD Tips
1. Create a check list of tests
2. Small step approach during refactorization (or
larger when fealing comfortable)
3. Add problems to the list, instead of resolving
them immediately
4. Never create new test if previous one is
failing

35. TDD Tips
1. Create a check list of tests
2. Small step approach during refactorization (or
larger when fealing comfortable)
3. Add problems to the list, instead of resolving
them immediately
4. Never create new test if previous one is
failing
5. Remove repetition (between code and test
too!)

36. TDD Tips
1. Create a check list of tests
2. Small step approach during refactorization (or
larger when fealing comfortable)
3. Add problems to the list, instead of resolving
them immediately
4. Never create new test if previous one is
failing
5. Remove repetition (between code and test
too!)
6. Tests should be fast and isolated

37. TDD Tips
1. Create a check list of tests
2. Small step approach during refactorization (or
larger when fealing comfortable)
3. Add problems to the list, instead of resolving
them immediately
4. Never create new test if previous one is
failing
5. Remove repetition (between code and test
too!)
6. Tests should be fast and isolated
7. Test only public

38. TDD Tips
1. Create a check list of tests
2. Small step approach during refactorization (or
larger when fealing comfortable)
3. Add problems to the list, instead of resolving
them immediately
4. Never create new test if previous one is failing
5. Remove repetition (between code and test too!)
6. Tests should be fast and isolated
7. Test only public
8. Write your own tests, don’t wait for a
teammate

39. London vs Brooklyn School of
TDD
Is it all about Mocks?

40. Check List
1. History of TDD
2. TDD Cycle of life
1. Red phase
2. Green phase
3. Refactoring
3. Tests measurement
4. TDD Tips
5. London vs Brooklyn
6. BDD
7. TDD is dead?
8. PHPSpec

41. Behavior Driven Development
- Based on TDD
- Test behavior, not code!
- Domain Driven Desing
- DSL in test tools
- „it_should”
- Gherkin [Given, When, Then]
- Tests as specification

42. Check List
1. History of TDD
2. TDD Cycle of life
1. Red phase
2. Green phase
3. Refactoring
3. Tests measurement
4. TDD Tips
5. London vs Brooklyn
6. BDD
7. TDD is dead?
8. PHPSpec

43. TDD is Dead?
Who said that ?!
David Heinemeier Hansson (RoR author and
Bacecamp founder)
http://martinfowler.com/articles/is-tdd-dead/
http://www.infoq.com/news/2014/06/tdd-dead-
controversy

44. Check List
1. History of TDD
2. TDD Cycle of life
1. Red phase
2. Green phase
3. Refactoring
3. Tests measurement
4. TDD Tips
5. London vs Brooklyn
6. BDD
7. TDD is dead?
8. PHPSpec

45. PHPSpec
Let’s do some live coding!