Test Driven Development


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Test Driven Development

  1. 1. Email (samnang.chhun@gmail.com) Blog (http://tech.wowkhmer.com) Rails Developer .NET Developer
  2. 2. About Testing! Test Last or DDD (Design Driven Tests)
  3. 3. Short development iterations Is a design process Based on requirement and pre-written test cases Tests are your first users The goal is to produce working clean code that fulfills requirements If TDD hurts then you're doing it wrong
  4. 4. Unnecessary Codes Unchangeable Codes Unintelligible Code
  5. 5. Makes you think about required behavior. Provides documentation. Improves quality. Reduces speculative code. Less time debugging. Confidence in change Discover usability issues early
  6. 6. I don’t have time to unit test. The client pays me to develop code, not write unit test. I am supporting a legacy application without unit tests. QA and User Acceptance Testing is far more effective in finding bugs. I don’t know how to unit test, or I don’t know how to write good unit tests.
  7. 7. It forces you to really understand the code. It forces you to really understand the tests It forces you to create code that is truly reusable and modular and testable These forces drive you to keep your code and your tests simple and easy to understand.
  8. 8. Enabling TDD TDD Cycle Choosing the First Test? Green Bar Patterns State-based vs. Interaction-based Unit Testing
  9. 9. NUnit Resharper MbUnit TDD.NET VSTS Refactor Pro! xUnit.net Visual Studio Moq Rhino Mocks
  10. 10. create a failing test remove write duplicatio just n clarify enough intent to pass
  11. 11. RED Refactor Green
  12. 12. The simplest. The essence. If you need to write code that is untested, choose a simpler test. If the essence approach takes to much time to implement, choose a simpler test.
  13. 13. Small and focused Intention revealing Repeatable Independent Have no side-effects
  14. 14. Description should be • Domain-specific • Suitable for customer comprehension • Understandable in absence of code Writing descriptions • Think about behavior • Think about the context of the behavior • Focus on the words, not the implementation
  15. 15. Fake It(Til You Make It) Start with hardcoded results and wait until later tests to force them to become real. Triangulate To Abstraction Make the code abstract only when you have two or more examples. Obvious Implementation aka Don't Be Stupid If you really, really, honestly know the right way to implement it, then write it that way.