battle of the mocking frameworks

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Session from NDC London 2013 Writing unit tests is hard, isn't it? you need an entire set of tools just to start. One of the crucial decisions when building this set is picking up a mocking framework. But BEWARE! what you choose has the ability to make you or break you! Come to the session and see Dror Helper, once a mocking framework developer, show the good and the bad of different mocking frameworks (free and commercial) and make them battle to the death!


  • 1.Dror Helper | @dhelper | Battle of the Mocking Frameworks

2. Consultant @CodeValue Developing software (professionally) since 2002 Disclaimer: I used to work @Typemock Blogger: About.ME 3. This is unit testa [Test] public void AddTest() { var cut = new Calculator(); var result = cut.Add(2, 3); Assert.AreEqual(5, result); } 4. Real code has dependencies Unit test Code under test Dependency Dependency 5. The solution - Mocking Unit test Code under test DependencyFake object(s) 6. Replace production logic with custom logic We do this in order to Focus the test on one class only Test Interaction Simplify Unit test writing Isolation 7. What is a Mock? mock objects are simulated objects that mimic the behavior of real objects in controlled ways [From Wikipedia] I prefer to call them Fakes 8. Manual/Hand-rolled mock Use inheritance to replace production logic. Use configurable delegates as custom logic. PasswordChecker PasswordChecker(IDataAccess) CheckPassword(string, string) DataAccess GetUserByName(string) SaveUser(string, string) 9. The problem Maintainability its a lot of work Gets complicated as more functionality is required: Production logic inside fakes Error prone - how do we avoid bugs in test? 10. Create Fake objects Set behavior on fake objects Verify method was called And more... What Mocking framework can do for you? 11. Meanwhile in the .NET world Open source FakeItEasy Moq NMock3 nSubtitute Rhino Mocks Free MS Fakes Commercial Isolator JustMock 12. Usage statistics (2012) Moq 45% Rhino Mocks 23% None 9% FakeItEasy 6% Nsubstitute 6% Isolator 4% Moles 2% MS Fakes 2% JustMocks 2% Other 1% 13. Married into your (test) code Saves/waste development time Affects design Choosing the right framework is crucial 14. Round 1 - API 15. Mock-Demo DB Read Data Request Response 16. API summary Error msgParametersBuilderSPEReadability +ExplicitYesNo+Moq -ExplicitNoNo+Rhino-Mocks +ExplicitNoYes+FakeItEasy +ExplicitNoNo+nSubtitute ?ExplicitYesNo-NMock3 +ImplicitNoYes+Isolator -ExplicitNoYes+JustMock N/AExplicitYesNo-MS Fakes Error msgParametersBuilderSPEReadability +ExplicitYesNo+Moq -ExplicitNoNo+Rhino-Mocks +ExplicitNoYes+FakeItEasy +ExplicitNoNo+nSubtitute ?ExplicitYesNo-NMock3 +ImplicitNoYes+Isolator -ExplicitNoYes+JustMock N/AExplicitYesNo-MS Fakes 17. Round 2 - Robustness Code under test API changes Method signature Method name Code under test internal changes Unexpected call to fake Return value from unspecified method Future proof 18. Round 3 Unconstrained 19. Constrained Fake by inheritance Force architecture Dependency injection (DI) Code by interfaces (LSP) Wrapping of the unfakeable Real object Fake object 20. Unconstrained Profiler API based Can fake almost anything 3rd party systems Legacy code Design your code - not for testability Can be used as if they are constrained Real Object Dependency Fake 21. Constraint NMock3 FakeItEasy nSubtitute Moq RhinoMocks Unconstraint Isolator JustMock MS Fakes 22. Nickels and dimes Constraint frameworks are free but can you afford them? How much does it cost if every task takes 1 hour more? How much does it cost not to use unit tests? 23. Round 4 - deployment 24. Deployment the bottom line MS FakesJustMockIsolatorConstraint Visual studio 2012/2013 Install on each machine. Install on each machine. Auto-run correct version Nothing (NuGet) Dev machine Only TFS (> 2012)Install on each machine. Install or use AutoDeploy NothingBuild Server Only TFS (> 2012)Environment vars JustMockRunner Build Tasks Environment vars TMockRunner Build Tasks Just run itRun tests on build machine Only VS profilersUse LinkerAutomatic LinkerWorks!Profilers Support 25. Which framework is better? 26. Dror Helper C: 972.05.7668543 e: B: w: