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TDD - Agile

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Test driven development insight

Test driven development insight

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  • 1. TDD (JSAG)
    Presented By : Harinder Singh Bedi
    6 July 2011
  • 2. Agenda
  • Test Driven Development (TDD) or Test First Development is a Software Development technique and one of the key factors of Extreme Programming Methodology.
    Test Driven Development
  • 10. Development Approaches
    • Ad hoc development
    • 11. Writing pseudo code first
    • 12. Model Driven Development (MDD)
    • 13. Test Driven Development (TDD)
  • What is TDD ?
    TDD = Test First Development + Refactoring
  • 14. How Does TDD Help
    • Ensures that your design is clean by focusing on creation of operations that are callable and testable
    • 15. Shortens the programming feedback loop
    • 16. Provides detailed specification through tests
    • 17. Provides concrete evidence that your software works
    • 18. Supports evolutionary development.
  • TDD says ..
    When we have a new feature to implement, we initially often think, ok how should I implement this ?
    But TDD says don't do it!
    "In TDD, the greater emphasis is on the usage rather than implementation"
  • 19. Steps to start TDD
    Analyze the requirements and write the list of tasks or features
    Pick a task or feature
    Brainstorm a list of tests for the task or feature
    Review the tests list and pick a test
    Write the test case
    Run the test case and see it fails to compile
    Write only enough code that the test case compiles
    Run the test and see running the code fails
    Write only enough code to just pass the test
    Refactor the production code and eliminate duplication
    Repeat
  • 20. When a bug is found ..
    First create a test case to reveal the bug
    Modify the production code so that the failed test passes
    Finally run all the tests and make sure your bug is fixed and covered.
  • 21. Refactoring is one of the most important parts of TDD, which means you need to refine the code design as you add new tests.Refactoring should be done consistently as you increment the software, adding tests and production code.
    Refactoring
  • 22. TDD terminology
    Testcase : Function or method that tests one behavior of the code
    Testsuite : Set of test cases, typically grouped by fixture.
    Fixture : generated via a setUp() method and destroyed in tearDown().
    Assertion Function or macro allowing to compare the expected value against the actual one.
    setUp() : It is a method of the Test Case class in jUnit that can be redefined in your Test class and used to create the execution environment for all test cases in the class.
  • 23. TDD terminology
    Refactoring : is a source code manipulation to improving the design of the code, without altering its external behavior.
    Unit : what is being tested, ranging from a single method to a set of classes.
    Mock object an object implementing the same interface as, or sub classing a class of the production code, and exhibiting a deterministic behavior.
    Red bar and green bar : comes from the graphical version of JUnit, where progression bar shows the execution of the tests, and goes from green to red when a test fails.
  • 24. TDD Benefits
    Test Coverage : TDD does make sure that virtually every line is executed and tested.
    Test Repeatability : Having the tests to back you up can give you the courage to make changes that would otherwise be too risky to make.
    Documentation : The tests describe your understanding of how the code should behave. They also describe the API. Therefore, the tests are a form of documentation.
    API Design : when you write tests first, you put yourself in the position of a user of your program's API.
  • 25. TDD Benefits
    System Design: A module that is independently testable is a module that is decoupled from the rest of the system.
    Reduced Debugging : When you move in the tiny little steps recommended by TDD, it is hardly ever necessary to use the debugger.
    Confidence : If you observe a team of developers who are practicing TDD, you will notice that every pair of developer had their code working a minute ago.
  • 26. Testing libraries
    Java - JUnit
    Ruby – Test::Unit
    Javascript – Test.More or JSUnit no clear standard
    C++ - CPPUnit
    PHP - PHPUnit
    Python - PyUnit
  • 27. TDD frameworks
    JUnit : It is the primary test tool for satisfying the first requirement for a Java test framework.
    Tutorial Reference : harinder1637Share-dTDDCouse material
    Mockito : is a Java-based framework for creating mock objects. It allows developers to create mocks based on classes or interfaces, specify behavior and return values for methods, and verify interactions.
    Tutorial Reference : http://gojko.net/2009/10/23/mockito-in-six-easy-examples/
  • 28. Continuous integration
    Continuous integration (CI) is a software engineering practice in which isolated changes are immediately tested and reported on when they are added to a larger code base. The goal of CI is to provide rapid feedback so that if a defect is introduced into the code base, it can be identified and corrected as soon as possible.
    Continuous integration software tools can be used to automate the testing and build a document trail.
  • 29. Best Practices of CI
    • Automate the build
    • 30. Create Tests to make the build self-testing
    • 31. Everyone commits to the baseline every day
    • 32. Every commit (to baseline) should be built
    • 33. Everyone can see the results of the latest build
    • 34. Automate deployment
    • 35. Automation testing is absolute essential as the system grows e.g. selenium, fitnesse
    • Having a tester in the team from day 1 is a MUST
    • 36. By the time developer is ready with a feature, Tester is also ready with scripts to break the feature
    • 37. Testers should evaluate requirements and should actively participate with product team to do analysis
    TDD tests provide a way so that every developer machine can be tested. Also tests make the build self-testing.
  • 38. Software tools to support CI
    • Hudson – powerful software written in Java to automate build software,
    supports CVS, SVN, Git, Ant, Maven.
    • Bamboo -- toautomate build software.
    • 39. BuildMaster -- proprietary application life cycle management and continuous
    integration tool by Inedo.
  • 40. Questions / Queries / Feedback ?
    Send to feedback@nagarro.com
    Thank You