Introduction to Unit Testing

Basic introduction to unit testing.

Transcript

1. P2P Code Academy
   Introduction to Unit Testing
   27th June 2012
   

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2. Table Of Contents
   • Putting Things in Context
   • What is Unit Testing?
   • Why should I care?
   • How does it work?
   • Unit Tests in Action
   • Extra Goodies
   

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3. Context
   

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4. We All Have Tested Before
   • Manual tests
   • Least efficient
   

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6. Unit Testing in Software
   • Functional Tests
   – Unit Tests
   – Integration Tests
   – System Tests
   – System Integration Tests
   • Non Functional Tests
   – Security, Performance, Usability…
   

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7. What are Unit Tests
   

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8. Integration Test
   Unit Test
   Tests that Test Units Of Code
   in Isolation
   low level
   

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9. Automated and Repeatable
   • Run With One Click*
   • Deterministic
   • Once Written Remain For Future Use
   • Anyone Can Run Them
   • Easy to Implement and Run
   • Run Quickly
   * It can be fully automated
   

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10. Trustworthy
    Readable
    Maintainable
    

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11. A Simple Unit Test
    

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12. A Simple Unit Test
    

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13. Unit Tests. Summary
    • Test Units of Code in Isolation
    • Automated and Repeatable
    • Easy to Implement and Run
    • Run Quickly
    • Trustworthy, Readable and Maintainable
    

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14. Why Should I Care
    

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15. Unit tests prove that
    your code actually works
    rnsure correctness
    works
    

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16. Unit tests provide ultra-fast feedback
    demonstrate concrete progress
    increase productivity
    keeps you in the zone
    

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17. Unit tests provide a safety-net and a
    sense of security
    it’s more fun to code with them than without
    low-level regression test suite
    refactor mercilessly
    improve design without breaking it
    

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18. Unit tests provide
    high granularity bug detection
    reduces the cost of bugs
    pinpoint a bug to the method-level
    

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19. Unit tests provide
    a living documentation
    it is always up-to-date
    it compiles!
    makes knowledge sharing easier
    

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20. Unit Tests impose
    good design principles
    

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21. Written by one, everyone benefits
    

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22. Unit tests are one of the basic
    foundation components that enables
    continuous integration and
    continuous delivery
    

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24. Why Should I Care Wrap-Up
    • Prove That Your Code Works
    • Ultra-Fast Feedback
    • Safety Net & Sense of Security
    • Super High Granularity
    • Living Documentation (always up-to-date)
    • Impose Good Design Principles
    • Written by one, everyone benefits
    • Basic block for CI and CD
    

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25. How Does Unit Testing Work
    

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26. All You Need Is Love
    • Unit Test Framework
    • Mocking Framework
    

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27. The Unit Test Framework
    • Unit testing API
    • Test Runner
    

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28. Different Frameworks
    • Visual Studio Testing Framework (not MSTest)
    • NUnit
    • MbUnit
    • ...
    http://bit.ly/list-of-dotnet-unit-testing-frameworks
    use one and you pretty much can use all
    

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29. The Unit Testing API
    • Way to mark code as test-code
    • Organize tests
    • Assertion library
    

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30. Mark Code As Tests
    and Organizing Tests
    • Use of C# Attributes
    • [TestClass] and [TestMethod]
    • [TestCategory(“awesome-tests”)]
    • [Ignore]
    

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31. Assertion Library
    • Let’s you assert correctness
    • Provides a lot of built-in assertions
    • Microsoft.VisualStudio.TestTools.UnitTesting
    http://bit.ly/using-the-assert-classes
    

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32. Basic Assertions
    • Static class Assert
    Assert.AreEqual(T expected, T actual)
    Assert.AreNotEqual(T noExpected, T actual)
    Assert.AreSame(T expected, T actual)
    Assert.IsTrue(bool condition)
    Assert.IsFalse(bool condition)
    Assert.IsNull(object value)
    Assert.IsInstanceOfType(object value, Type expectedType)
    

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33. Assertions Also Available For
    • Collections AssertCollection
    • Strings AssertString
    CollectionAssert.AllItemsAreInstancesOfType(ICollection collection, Type type)
    CollectionAssert.AllItemsAreNotNull(ICollection collection)
    StringAssert.Contains(string value, string substring)
    StringAssert.StartsWith(string value, string substring)
    

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34. Asserting Exceptions
    • [ExpectedException(typeof(MyException))]
    

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35. The Unit Test Runner
    • Runs Tests
    • Provides feedback
    • Red/Yellow/Green
    

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36. DEMO
    Using VS Testing Framework
    

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37. Using Visual Studio Testing
    Framework. Summary
    1. Created a Test project
    2. Created a Test class
    3. Created a method to test Calculator.Add()
    1. Used AAA (Arrange, Act, Assert) pattern
    4. Created a method to test Calculator.Substract()
    5. Used [TestInitialize] and [TestCleanup] to make our
    test suite more maintanable
    6. Illustrated what happens when a bug is introduced
    

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38. Mocks And Stubs
    Testing in Isolation
    

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39. What happens when a class has
    dependencies?
    

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40. Imagine...
    

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41. Use Fake Objects
    to Isolate Class Under Text
    ensure that class under
    test is in complete
    isolation
    

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42. What are Fake Objects
    crash test dummy simile
    

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43. Two Types of Fake Objects
    • Stubs (passive testing)
    • Mocks (active testing)
    

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44. Mocking Framework
    • Makes it easy to create Fake Objects
    • Lots of Mocking Frameworks:
    – Moq
    – RhinoMocks
    – EasyMock.NET
    – Nmock
    – …
    http://bit.ly/what-csharp-mocking-framework-to-use
    

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45. How To Create Fake Objects
    With Moq
    Bang!
    and you have a fake object that implements the
    IScreen interface!
    var fakeScreen = new Mock();
    

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46. DEMO
    Using Moq
    

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47. Using Moq. Summary
    1. Install Moq using NuGet
    2. Created two fake objects using Moq
    3. Used fake objects to isolate the Calculator class
    

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48. Testing Best Practices
    • Naming Conventions
    • AAA (Arrange Act Assert pattern)
    • Heuristics
    

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49. Testing Naming Conventions
    

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50. General Heuristics
    • No logic in tests
    • Make sure the tests test only one thing
    • Separate unit tests from integration tests
    • Check test coverage by playing with values
    • Avoid code duplication
    

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51. General Heuristics II
    • Don’t abuse TestInitialize and TestCleanup
    • Make sure tests are isolated and repeatable
    • Most test should have one only assert
    • Only one mock per test
    • Use good naming conventions
    

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52. Disadvantages Of Unit Testing
    • None really, if well done
    – Write more Code
    – Maintain more code
    • If not well done, they have no value
    

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53. Treat your tests as
    if they were production code
    

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54. EXERCISE
    UNIT TESTING IN ACTION
    

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55. Extra Goodies
    • Test Driven Development
    • Behavior Driven Development
    • Awesome Tools
    

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56. Test Driven Development
    • Write test before production code
    • Test drives design
    • Test-Implement-Refactor cycle
    – Red/Green/Refactor
    

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57. Test Driven Development
    Benefits
    • You are the first user of your code
    • Only write the code you need to pass a test
    • Implement testable code
    • High test coverage
    • Increases productivity (red-green-refactor)
    • Increases quality (refactor)
    

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58. Behavior Driven Development
    

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59. Awesome Tooling
    • NCrunch and Mighty Moose
    • Tests run always
    This test passed
    visual code coverage
    Code hasn’t
    been run yet
    status
    

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60. And Remember...
    

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61. If you want to know more...
    

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62. If you want to know more...
    

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63. References
    • The Art Of Unit Testing
    http://amzn.to/the-art-of-unit-testing
    • Coding Horror
    http://bit.ly/i-pity-the-fool-who-doesnt-write-unit-tests
    

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64. Thank you
    

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