TDD, DDD & Teamwork

Transcript

2. TDD, DDD & Teamwork @jlammerts @pelshoff
3. Part I: TDD
4. What is a test?
5. Something shouldn’t happen • Expect exception • Do the thing
6. final class PresentationTest extends TestCase { /** * @test */ public function presentationsShouldHaveTitles(): void { $this->expectException(InvalidPresentation::class); new Presentation('', '', ''); } }
7. Something should happen • Do the thing • Expect result
8. final class PresentationTest extends TestCase { /** * @test */ public function presentationsShouldAllowNewSubtitles(): void { $actual = new Presentation('With', 'a', 'title'); $expectation = new Presentation('With', 'another', 'title'); $actual->changeSubtitleTo('another'); $this->assertEquals($expectation, $actual); } }
9. What is a good test?
10. A good test... • Arrange • Act • Assert
11. A good test... • Setup • Expect • Execute • Verify
12. A good test... • Setup • Expect • Perform • Assert
13. A good test... • Given • When • Then
14. What is TDD?
15. “Test-Driven Development (TDD) is a technique for building software that guides software development by writing tests.” - Martin Fowler
16. Three steps of TDD • Red • Green • Refactor
17. What is the difference between test-first & TDD?
18. Recap • Given, When, Then • Red, Green, Refactor • Client-first
19. Good luck and have fun!
20. Part II: Teamwork
21. The Attitude Model
22. Divergent
23. Convergent
24. Divergent Tend to be… • Open • Optimistic and curious • Quick, sloppy and careless
25. Convergent Tend to be... • Closed • Pessimistic and inquisitive • Paced, diligent and careful
26. The Double Design Diamond
28. Good luck and have fun!
29. Part III: DDD
30. Value objects
31. final class Name { private $lastName; private $firstName; private $insertion; public function __construct(string $lastName, string $firstName, string $insertion) { $this->lastName = $lastName; $this->firstName = $firstName; $this->insertion = $insertion; $this->nameMustHaveLastName(); } private function nameMustHaveLastName(): void { if (!$this->lastName) { throw InvalidName::becauseLastNameIsMissing(); } } public function getLastName(): string { /**/ } public function getFirstName(): string { /**/ } public function getInsertion(): string { /**/ } }
32. final class EmailAddress { private $emailAddress; public function __construct(string $emailAddress) { $this->emailAddress = $emailAddress; $this->emailAddressMustBeAnActualEmailAddress(); } private function emailAddressMustBeAnActualEmailAddress(): void { if (!filter_var($this->emailAddress, FILTER_VALIDATE_EMAIL)) { throw InvalidEmailAddress::becauseThisIsNotAnEmailAddress(); } } public function asString(): string { return $this->emailAddress; } }
33. Value objects • Express a value • Define allowed values • Are immutable • Are easy to test
34. Entities
35. final class Attendee { private $id; private $name; private $emailAddress; public function __construct(Uuid $id, Name $name, EmailAddress $emailAddress) { $this->id = $id; $this->name = $name; $this->emailAddress = $emailAddress; } public function getId(): Uuid { /**/ } public function getName(): Name { /**/ } public function setName(Name $name): Attendee { /**/ } public function getEmailAddress(): EmailAddress { /**/ } public function setEmailAddress(EmailAddress $emailAddress): Attendee { $this->emailAddress = $emailAddress; return $this; } }
36. Entities • Have identity • Are more than their attributes • Evolve over time • Are slightly harder to test
37. Services
38. final class Registration { private $repository; public function __construct(AttendeeRepository $repository) { $this->repository = $repository; } public function registerNew(Attendee $attendee): void { $this->emailAddressMustBeUnique($attendee->getEmailAddress()); $this->repository->add($attendee); } private function emailAddressMustBeUnique(EmailAddress $emailAddress): void { try { $this->repository->findByEmailAddress($emailAddress); } catch (AttendeeNotFound $e) { return; } throw RegistrationFailed::becauseEmailAddressIsNotUnique(); } }
39. Services • Have no identity or attributes (Are not a “thing”) • Tackle cross-concern operations • Are harder to test
40. Context Technische bouwblokken Quiz Case study I Case study II
41. class Address
42. class BicycleService
43. class StreetAddress
44. class Investment
45. Good luck and have fun!
46. The end! @jlammerts @pelshoff https://joind.in/event/php-yorkshire-2019/tdd-ddd--teamwork