Unit Testing presentation going through advantages, naming convention, testing frameworks, mocking frameworks...

1. Unit Testing
François Camus

2. Advantages
 Quick feedback loop
 Run all tests to know if something is broken
 Less need to run application to debug production code
 Can debug from test method instead
 Provides confidence
 Refactoring
 Releasing more often
 Documents production code behaviour
 Serves as production code safety net
 Avoids Change And Pray syndrome (CPD)

3. Test Project
 Contains tests for a specific project
 Naming convention
 To avoid confusion
 e.g. when browsing files
 e.g. when having lots of tabs
 Library namespace
 e.g. OpenControl.Web.Mappers
 Library Test Project namespace
 e.g. OpenControl.Web.Mappers.Tests
 Test Class name
 e.g. ModelMapperTests
 Test project to follow same structure as project being
tested

4. Unit Testing frameworks
 Microsoft Test framework
 NUnit
 xUnit.net
 http://xunit.codeplex.com/wikipage?title=Comparisons

5. Test Execution Lifecycle
 Initialization (before each test execution)
 initialises dependencies and fields that are common to many tests
 no setup here: each test does its own setup
 Easier to maintain test code
 Don’t want spaghetti test code all depending on a common setup method
 Execution
 Does local test setup
 Calls method to test passing parameters and storing result if any
 Asserts something on result or behaviour
 Cleanup (after each test execution)
 Dispose of initialized dependencies
 Test Class initialisation and cleanup
 Usually used by custom testing framework
 e.g. Tester base class containing test helpers
 Initialises before first test execution
 Cleans up after last test execution

6. Test method naming convention
[Fact]
public void Method_Condition_Result() {}
1. Method being tested
2. Condition to meet test result (optional)
3. Test result
[Fact]
public void GetData_DataExists_ReturnsData() {}

7. Test method structure
 AAA: Arrange/Act/Assert
1. Arrange: local test setup
2. Act: calls method to test
3. Assert: asserts result or behaviour
 Common structure to all tests
 Easier for other developers to maintain code
 Helpful when doing Test Driven Development

8. Interaction based Unit Testing
 Asserting expectation on method
 Couples to internal implementation
 Less flexible to do refactoring
 Leads to fragile tests
 Easier when starting unit testing
 Unavoidable
 Need them when unable to only test result
 e.g Testing that a void method was called
 About 10% of tests
 http://programmaticallyspeaking.com/?p=713

9. State based Unit Testing
 Tests method result rather than expectation
 Easier to maintain
 Only local test setup may need amendment
 Preferred form of unit testing

10. Testing internals
 Add attribute to production code assembly info to make
internals visible to specific library
[assembly: InternalsVisibleTo("OpenControl.ClassLibrary.Tests")]
 http://ayende.com/Wiki/Rhino+Mocks+-
+Internal+Methods.ashx

11. One assert per test
 Atomic
 Easier to understand
 Easier to maintain
 When refactoring production code, you get better
feedback on what breaks

12. Dependency Injection
 Constructor parameter injection
 Property injection

13. Mocking
 Mocking frameworks (all based on Castle Dynamic Proxy)
 http://www.castleproject.org/projects/dynamicproxy/
 Add attribute to production code assembly info:
[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")]
 NSubstitute
 Shorter but awkward syntax
 Less lambda so changing developers’ habits
 Rhino Mocks
 Too big (“Does the coffee !” Manu)
 Confusion for new users on which syntax to use
 Latest syntax is following state based unit testing approach
 But old syntax remains
 Large community
 Moq
 Smaller and simpler
 Large community
 http://code.google.com/p/moq/wiki/QuickStart

14. Tools
 Test Driven .Net (visual studio extension)
 Works with xUnit.net (may need to run xunit installer to add
support to Test Driven .Net)
 ReSharper...
 Jenkins
 After build runs tests via plugin (xUnit plugin...)
 Need to upgrade Jenkins to support .NET 4+

15. Conclusion
 Questions ?
 TDD next time