Production Code Without Tests v2

Second version of my talk about the legacy code without tests and the ways we can improve that

Transcript

1. PRODUCTION CODE WITHOUT TESTS Akim Khalilov WEBCONSULTANTS
2. About me: Developing e-commerce applications for Eastern Europe: • 8 countries • 3 web-application • 1М+ users @sstude http://sstude.com
3. Agenda o Why the code without tests is a problem? o Real-world example of our application. o What do we need to change – code, and not only? o Profit.
4. Code without tests What is the problem?
5. Problem is that o It’s complicated • Hard to understand o A lot of “gotchas” • It’s hard not to break anything o It happens every time...
6. Story of one application o 9 countries, 1k operations with orders per day o 6+ years of development o Absence of tests, documentation, business analysts (changing) o All responsibility is on developers (two DEVs)
7. Story of one application o People is happy while app works o Request for a new feature o Problem – do not break the code • During development • During bug fixing • During refactoring
8. Code is not ready for unit tests o Structure violation o Tight coupling o Spaghetti-code o God object o Static method calls (a lot) o Dependencies on external resources (services, file system, database, ...)
9. o Several classes per one file o Flat solution structure o Duplicate structure o Absence of grouping by some principles (internal / external) Structure complicates the search
10. Structure o Extract namespace and folders o Avoid duplication o Group by business rules (Processors, DeliveryHandlers, …) o Group by technology (NH, Forms, Controllers, … ) o Group by assemblies helps
11. Tight coupling
13. Injections  Into method
15. Injections  Into method  Into constructor
17. It is better, but We still are dealing with real service o Extract an interface for your code o Write a “wrapper” – for the third- party code the best, is to
19. Static method call
21. How to resolve the problem?  Do not use static   Exclude call to static methods for unit tests: o Subclass and Override Method o Extract and Override Call
22. Subclass and Override Method
23. Override the result
24. It’s better, but if we need more? We need to override two methods Extract and Override Call
26. Use in test
27. “Proper” unit-test frameworks Do not use the ones, that just do intercept the call – there is the risk to leave the system as is, without any change
28. New code in legacy New code could be covered by tests – it’s new  Implement it in a new method / class (Sprout method / class) Call it from the legacy code
29. TR: Client can pay the bill
30. TR: Balance could not be negative
31. Sprout Method
32. New code could be covered by tests
33. Small-methods problem o Temporary state of the design o Step to refactor the system o Step to write unit tests o With the idea to refactor the system globally
34. This is not going to work in my team You need:  Arrange your code – refactoring  Arrange your team – idea  Arrange your management - time
35. Arrange your code o Refactor your code o Refactor your code continuously
36. Arrange your team o New code - with test o Bug fix - with test o Code is not ready o Can take more time o Refactor your code continuously (time?) o Run your tests continuously - CI
37. Arrange your team Pay attention to red tests. Not pure TDD: Did the broken test was fragile? Or the system was broken and the test did saved you…
38. Arrange your team Time balance between refactoring and new tests. If you have no time, or there is complete overtime for your team – enthusiasm will end very soon.
39. Arrange your management Time balance between refactoring and new tests. Integrate to your existing iterations (Refactoring in overtime would not work too long)
40. Risks o Hard to do less (wish to change everything) o Tests will help in the future– it’s an investment o Management will fight back (time is money)
41. Profit  An investment to the code  Test will save in the future  Improve the system during refactoring  System is resistant to changes  Business-logic is well-documented for the team and new people
42. Thank you Questions? Akim Khalilov WEBCONSULTANTS @sstude http://sstude.com