Benefit From Unit Testing In The Real World


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  • The lecture today will be divided into four parts:1 Overview of Unit tests and TDD and how it could save money for companies and improve software development process2 Typical day (but nor all day) of a software developer that uses TDD3 Real examples of Unit testing in non trivial cases4 Answer questions from the audience about the lecture, TDD & Unit testing in their companies
  • How a software company can benefit from unit testing Question to audience:Who knows what are unit tests?Who uses unit tests?Who practices TDD?
  • Why unit test:Define unit testing, define isolationMotivationWhy not do unit testing?Benefits: regression, confidence in changeStatistics Examples of companies that unit testCommon misconceptions:Not all tests are unit tests (integration vs. unit testing)Unit tests are for developers, not QAIntroducing TDDTools:Unit testing frameworksR#Mocking frameworksTeamCity/Team SystemFinalBuilder/msbuild/ccnet
  • Show unit test parts:Declaration (attribute)Run code under testAssertion – did satisfy condition Usually we have an additional part that arrange the needed componentsShould this be a new slide? What does unit test test?Functional requirememts
  • First explain - Difference between unit testing – how and tdd - methodologyTest Driven Development (or test driven design) is a methodology.Write a test that failsRun tests – why should we – to make sure the test actually checks the right thingWrite codeRefactorRepeat if nessesary
  • No that we understand what is unit testing and TDD I’d like
  • Taken from quality improvement through test driven development: results and experiences of four industrial teamsPublished online: 27 February 2008
  • - One known fact is that most of the bugs are introduced during the development stage.Another known fact is that the cost to fix a defect increases exponentially over stages.When bug is found at Testing phase the application needs to go back to development and it actually takes more time!It would be better to find/fix/not create bugs during development afterward it’s too late.We get a costly fix and frustrated clients.Show bugs in testing/supprt – where did they come from? Every few defects fixed a new defect is introducedOur pain in at the dev stage however many companies invest most of their money on QA & support
  • Give example about massive refactoring of new code.Function/code afraid to touch…
  • Examples DB, WCF
  • Has Teardown/Setup functionalityRun Unit tests
  • How to test part of a whole system
  • The backbone of TDD (and development)Show how CI & script runner run the test suite – perhaps publish results to web
  • Continuous integration is the backbone of TDD. Without test runner that runs each time code changes it is impossible to make sure that nothing was broken.
  • Should show:? Get code from server ?MSTest/NUnit
  • Should show:NUnit
  • Resharper
  • Benefit From Unit Testing In The Real World

    1. 1. Dror Helper - Doron Peretz – Typemock Ltd. Typemock™
    2. 2. Typemock™  Typemock Isolator  Established 2005, privately owned  Thousands of customers (Fortune 500)  Tens of thousands licenses sold Typemock™
    3. 3. Agenda  Using TDD for Fun & Profit  A day in the life of TDD developer  Testing difficult scenarios  Share the Pain! Typemock™
    4. 4. ` How to implement unit testing in your development team Typemock™
    5. 5. Sounds Familiar? 20:00 – One bug left before release 20:01 - Done! 20:02 - Send version to QA, call wife 20:05 - On the way to the elevator. QA: It doesn’t work! 22:50 - What have I done?! Typemock™
    6. 6. Unit testing for Fun & Profit  Short Overview: Unit Test, TDD  Why unit test?  Things you thought you knew  Tools you need to know about Typemock™
    7. 7. Overview What is Unit Test?  Verifies an atomic piece of code  Tests one specific behavior  Each Test is autonomous [TestMethod] public void CheckPassword_ValidUser_ReturnTrue() { bool result = CheckPassword(“user”, “pass”); Assert.IsTrue(result); } Typemock™
    8. 8. Overview Test Driven Development Write new Test Run Refactor Tests Run Write Tests code Typemock™
    9. 9. Why Unit Test? Why not use Unit Test Testing is for QA Time = Cost Integration Testing find more bugs Manual Testing find more bugs It’s like writing the code twice Typemock™
    10. 10. Why Unit Test? Is TDD a Waste of Time? Time taken to code a feature 140% 135% 120% 125% 120% 115% 100% 80% 60% 40% 20% 0% IBM: Drivers MS: Windows MS: MSN MS: VS WithoutTDD Using TDD Typemock™
    11. 11. Why Unit Test? Is TDD a Waste of Time? Using Test Driven Design 140% 120% 100% 80% 61% 60% 38% 40% 24% 20% 9% 0% IBM: Drivers MS: Windows MS: MSN MS: VS Major quality improvement for minor time investment Time To Code Feature Defect density of team Typemock™
    12. 12. Why Unit Test? So Why Unit Test? Where does it hurt? 100% 10 The pain is here! This is too late… 9 80% 8 % defects created 7 Thousand $s 60% 6 5 40% 4 3 20% 2 1 0% 0 Requirements Coding Integration Testing Typemock™ Support % of Defects Introduced Cost to Fix a Defect
    13. 13. Misconceptions TDD is not about testing  TDD is about design and development  By testing first you design your code Typemock™
    14. 14. Misconceptions Unit Tests are written by developers!  Increase confidence in code  Fearlessly change your code  Document requirements  Discover usability issues early Typemock™
    15. 15. Misconceptions Unit Tests are Not Integration  Unit tests should be:  Small  Atomic  Test a single functional unit  Isolated!  Integration tests are used to test system wide functionality Typemock™
    16. 16. Tools Unit Testing Frameworks  Consensus – NUnit  Integrated – MSTest  New kid on the block – XUnit  Performance oriented – Zenebug  Meta framework- Gallio (MBUnit) Typemock™
    17. 17. Tools Mocking / Isolation  Each unit test MUST be isolated  How do we test business logic without Database calls? Typemock™
    18. 18. Tools Isolation – Mocking frameowrks Open Source:  NMock2  Moq  Rhino Mocks Commercial (costs money but worth it)  Typemock Isolator Typemock™
    19. 19. Tools Visual Studio Integration Refactoring  Code Rush  R# Unit test runners  TestDriven.NET  R# Test Runner Typemock™
    20. 20. Tools Continuous Integration Build Server (TeamCity) What’s new? Commit There you go Source Control (SVN) We automatically got •Error reports & logs •New version installer •Help files •More… Build Agents Typemock™ (FinalBuilder)
    21. 21. Tools Continuous Integration Computer Says NO! Build Automation Tools  NAnt  MSBuild  FinalBuilder CI Servers  CCnet  TeamCity  Team System / Team Foundation Server  FinalBuilder Server Typemock™
    22. 22. ` Examples, demonstrations & fun Typemock™
    23. 23. A Day in the Life of a TDD'er  The tools we use at Typemock  Writing some code  OK, who broke the Build?!  Too much spare time… Typemock™
    24. 24. Our Tools The Tools We Use  Unit testing – MSTest/NUnit  Build automation – FinalBuilder Typemock™
    25. 25. Our Tools Build Script at a Glance Typemock™
    26. 26. Our Tools The Tools We Use  Unit testing – MSTest/NUnit  Build automation – FinalBuilder  Continuous Integration – TeamCity Typemock™
    27. 27. Our Tools TeamCity at a Glance Typemock™
    28. 28. Our Tools The Tools We Use  Unit testing – MSTest/NUnit  Build automation – FinalBuilder  Continuous Integration – TeamCity  Integrated tools – R#, TestDriven.NET  Isolation Framework – Isolator (surprise!)  Build Bunny! Typemock™
    29. 29. Write Code Writing Some Code  We begin with a clean slate Write new test Run Refactor tests Run All Write tests code Typemock™
    30. 30. Write Code Writing Some Code  An exercise in futility… Write new test Run Refactor tests Run all Write tests code Typemock™
    31. 31. Write Code Writing Some Code  Now we get our hands dirty Write new Test Run Refactor tests Run all Write tests code Typemock™
    32. 32. Write Code Writing Some Code  Make sure everything’s fine… Write new Test Run Refactor tests Run all Write tests code Typemock™
    33. 33. Write Code Writing Some Code  … and make it perform/look better Write new test Run Refactor tests Run all Write tests code Typemock™
    34. 34. Write Code Writing Some Code  Lets take her out for another spin… Write new Test Run Refactor tests Run all Write tests code Typemock™
    35. 35. Broken Build OK, Who Broke the Build?  Something went horribly wrong!  And it’s easy to find who to blame   But it’s easy to find out what happened  Why is this important?  The project heartbeat  Healthy build == easy to release Typemock™
    36. 36. Spare Time Too Much Spare Time  The foosball table  The build bunny  The Shooting of The Zombies  Helping children with computer skills Typemock™
    37. 37. Not everything in life is easy… Typemock™
    38. 38. Examples from the real world  Hard to unit test scenarios  How to solve this problem  Examples Typemock™
    39. 39. Difficult scenarios to Unit Test  Client – server architecture  Databases  Legacy Code  Closed Object Models (Sharepoint, Silverlight)  GUI interaction Typemock™
    40. 40. Possible solutions  First - better understand the problem  Design for Testability  Refactoring for Testability  Reflection  Mocks / Isolation  Last resort - Integration tests instead Typemock™
    41. 41. Example Unit Testing WCF Client Class: WCF Client Method: string GetSourceList(string source); Problem: Server connection is not possible Typemock™
    42. 42. Unit Testing WCF Client Overview: DataProviderClient DataProviderServer ISourceListProvider GetSourceList Typemock™
    43. 43. Unit Testing Windows Forms Database Registration Form Business Logic Registration Controller Typemock™
    44. 44. Share The Pain  Your unit testing stories  Q&A Typemock™
    45. 45. Thank you Want to learn more? Read about Test Driven Development & Isolation at the Typemock Insiders blog Follow up on Take a card and drop us an email! Typemock™