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TDD
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INTRODUCTION TOTEST DRIVEN DEVELOPMENT
tw: @MaciejGrajcarek
Check List
1. History of TDD2. TDD Cycles3. BDD4. TDD is dead?5. PHPSpec
Who needs tests anyway?
Who needs tests anyway? Bugs killers!
Technical Debt
Technical Debt
Where it all beganWaterfall Model
Winston W. Royce (1970)
Where it all beganAgile – best friend of TDD
- Adaptive vs Predictive- Iterative vs Waterfall
2001 – Agile Manifesto
Where it all beganScrum Cicle
Analysis
Programming
Testing
Acceptance
Where it all began
„Test Driven Development: By Example” – Kent Beck (2003)
Check List
1. History of TDD2. TDD Cycle of life3. BDD4. TDD is dead?5. PHPSpec
TDD Cycle of life
Failing Test
Pass testRefactoring
TDD Cycle of life
Failing Test
•Make test compile•Make sure it doesn’t pass
First simple failing test
function checkSumTest()
{
$a = 5;
$b = 4;
$calculator = new Calculator();
$sum = $calculator->sum($a, $b);
$this->assertEqual(9, $sum);
}
TDD Cycle of life
Pass test
•Fake It (Till You Make It)•Type The Obvious Implementation•Triangulation
Fake It (Till You Make It)
class Calculator
{
function sum($a, $b)
{
return 9;
}
}
Type The Obvious Implementation
class Calculator
{
function sum($a, $b)
{
$sum = $a + $b;
return $sum;
}
}
Triangulation
At least two points needed to find a location.
Triangulation
//Test 1$sum = $calculator->sum($a, $b);$this->assertEqual(9, $sum);
class Calculator{function sum($a, $b)
{ $sum = $a + $b; return $sum;}
}
Triangulation
//Test 1$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 $sum;}
}
Triangulation
//Test 1$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, $sum);
Triangulation
class Calculator{function sum()
{$elements = func_get_args();$sum = 0;foreach ($elements as $el) {
$sum += $el;}return $sum;
}}
Triangulation
//Test 1$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, $sum);
Triangulation
//Final test$sum = $calculator->sum(4, 5, 7, 1);
$this->assertEqual(17, $sum);
TDD Cycle of life
Refactoring•KISS•DRY
Maintainability, Flexibility, Portability, Reusability, Readability, Scalability, Testability, Understandability
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
TDD Cycle of life
Failing Test
Pass testRefactoring
Check List
1. History of TDD2. TDD Cycle of life
1. Red phase2. Green phase3. Refactoring
3. Tests measurement4. TDD Tips5. BDD6. TDD is dead?7. PHPSpec
Tests measurement
1. Code Coverage2. Underlay Defects
- 100 % code coverage != Error Free- Vendor code should have 100% code
coverage, but yours not necessarily
TDD Tips
1. Create a check list of tests
TDD Tips
1. Create a check list of tests2. Small step approach during
refactorization (or larger when fealing comfortable)
TDD Tips
1. Create a check list of tests2. Small step approach during
refactorization (or larger when fealing comfortable)
3. Add problems to the list, instead of resolving them immediately
TDD Tips
1. Create a check list of tests2. 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
TDD Tips
1. Create a check list of tests2. 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!)
TDD Tips
1. Create a check list of tests2. Small step approach during refactorization
(or larger when fealing comfortable)3. Add problems to the list, instead of
resolving them immediately4. Never create new test if previous one is
failing5. Remove repetition (between code and test
too!)6. Tests should be fast and isolated
TDD Tips
1. Create a check list of tests2. Small step approach during refactorization (or
larger when fealing comfortable)3. Add problems to the list, instead of resolving
them immediately4. Never create new test if previous one is failing5. Remove repetition (between code and test
too!)6. Tests should be fast and isolated7. Test only public
TDD Tips
1. Create a check list of tests2. Small step approach during refactorization (or
larger when fealing comfortable)3. Add problems to the list, instead of resolving
them immediately4. Never create new test if previous one is failing5. Remove repetition (between code and test too!)6. Tests should be fast and isolated7. Test only public8. Write your own tests, don’t wait for a
teammate
London vs Brooklyn School of TDD
Is it all about Mocks?
Check List
1. History of TDD2. TDD Cycle of life
1. Red phase2. Green phase3. Refactoring
3. Tests measurement4. TDD Tips5. London vs Brooklyn6. BDD7. TDD is dead?8. PHPSpec
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
Check List
1. History of TDD2. TDD Cycle of life
1. Red phase2. Green phase3. Refactoring
3. Tests measurement4. TDD Tips5. London vs Brooklyn6. BDD7. TDD is dead?8. PHPSpec
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
Check List
1. History of TDD2. TDD Cycle of life
1. Red phase2. Green phase3. Refactoring
3. Tests measurement4. TDD Tips5. London vs Brooklyn6. BDD7. TDD is dead?8. PHPSpec
PHPSpec
Let’s do some live coding!
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