Tuenti <3 Testing

Story of a healthy addiction

Transcript

1. Joaquin Engelmo kini@tuenti.com Tuenti <3 Testing (Story of a healthy addiction)
4. esting T
5. • We <3 our customers • Confidence • Safety Net • Refactoring, refactoring, refactoring • It is professional, guys :)
6. http://lisacrispin.com/2011/11/08/using-the-agile-testing-quadrants/
7. By Martin Fowler http://martinfowler.com/bliki/TestPyramid.html
8. • Black-box oriented tests • End to end • Web/phone/simulator • No tests doubles can be used • Needs a full and provisionable server environment • Slow tests Acceptance Tests Concepts
9. Acceptance Tests Environment KIF
10. • JVM/PHP/Whatever • No need external env set up • Tests run in build time • Use test doubles • Slower tests than unit tests Integration Tests Concepts
11. Integration Tests Environment
12. • JVM/PHP/Whatever • Application classes in isolation • Test doubles • Build time • Really fast tests Unit Tests Concepts
13. Unit Tests Environment • Fast • Isolated • Repeatable • Self-Verifing • Timely
14. Doubles • Stubs => Canned answers • Mocks => Stubs + verify • Spies => Record interaction info • Fake => I seem real but not • Dummy => I do nothing at all
15. What’s wrong with this?
19. Testability • Mixing object graph construction with application logic • Ask for things, don’t look for things • Doing work in constructor • Global State/Singletons • Static methods
20. Talk is cheap. Show me the code.
21. Testability Mixing object graph construction with application logic • Factories, these are full of the "new" operators and are responsible for building the object graph of the application, but don't do anything else. • Business logic classes, which are devoid of the "new" operator and are responsible for doing work.
22. Testability Mixing object graph construction with application logic
23. Testability Mixing object graph construction with application logic
24. Testability Mixing object graph construction with application logic
25. Testability Ask for things, don’t look for things • Just ask for all of the collaborators you need in your constructor. • But, if you find yourself needing to pass 10 collaborators to your constructor, maybe it's time to step back and think about the design
26. Testability Doing work in constructor • Any work you do in a constructor, you will have to successfully navigate through on every instantiation • There's no way to mock or handle work inside constructor. (actually there’s but you don’t wanna do it) • Do as little work in constructor as possible (Ideally just assigning passed parameters to the instance variables).
27. Testability Doing work in constructor
28. Testability Doing work in constructor
29. Testability Doing work in constructor
30. Testability Doing work in constructor
33. Testability Global State • Global State from the testing point of view is a real problem. • When tests modify global state, next run tests will be affected by this modification, this means that the order of the tests execution matters in this case. • Some tests can pass in isolation, but not when running them together. • Not sure about the current state of the global object. • Really hard to debug. • Tests cannot run in parallel.
34. Testability Singletons • Are global state in sheep’s clothing. • All of the internal objects of the singleton are global as well. • The core of the issue is that the global instance variables have transitive property!
35. Testability Static Methods • Procedural code has no seams (places where you can divert the normal execution flow) • How much a static method will hurt from a testing point of view depends on where it is in the application call graph. A leaf method such as Math.abs() is not a problem. But it could stop being a leaf in any moment when functionality needs to be changed.
36. Testability Global State & Singletons & Static Methods
37. Testability Global State & Singletons & Static Methods
38. Testability Global State & Singletons & Static Methods
39. rchitecture A
40. What are we going to use? • Clean Architecture • Microservices • S.O.L.I.D • Dependency Injection
41. Did you said ‘Clean’?
42. Uncle Bob Clean https://www.youtube.com/watch?v=WpkDN78P884 http://blog.8thlight.com/uncle-bob/2012/08/13/the-clean-architecture.html
43. Did you said ’SOLID’ too?
44. Uncle Bob S.O.L.I.D. http://butunclebob.com/ArticleS.UncleBob.PrinciplesOfOod • Single Responsibility • Open-Close • Liskov Substitution • Interface Segregation • Dependency Inversion
45. Thanks!