How do I write context/specification style unit tests with an MSTest/xUnit framework?

Question

I have been using MSpec to write my unit tests and really prefer the BDD style, I think it's a lot more readable. I'm now using Silverlight which MSpec doesn't support so I'm having to use MSTest but would still like to maintain a BDD style so am trying to work out a way to do this.

Just to explain what I'm trying to acheive, here's how I'd write an MSpec test

[Subject(typeof(Calculator))]     public class when_I_add_two_numbers : with_calculator {   Establish context = () => this.Calculator = new Calculator();   Because I_add_2_and_4 = () => this.Calculator.Add(2).Add(4);   It should_display_6 = () => this.Calculator.Result.ShouldEqual(6); }  public class with_calculator {   protected static Calculator; } 

So with MSTest I would try to write the test like this (although you can see it won't work because I've put in 2 TestInitialize attributes, but you get what I'm trying to do..)

[TestClass] public class when_I_add_two_numbers : with_calculator {    [TestInitialize]    public void GivenIHaveACalculator()    {       this.Calculator = new Calculator();    }     [TestInitialize]    public void WhenIAdd2And4()    {       this.Calculator.Add(2).Add(4);    }     [TestMethod]    public void ThenItShouldDisplay6()    {       this.Calculator.Result.ShouldEqual(6);    } }  public class with_calculator {   protected Calculator Calculator {get;set;} } 

Can anyone come up with some more elegant suggestions to write tests in this way with MSTest?

Answer 1

What you think about this one:

[TestClass] public class when_i_add_two_numbers : with_calculator {     public override void When()     {         this.calc.Add(2, 4);     }      [TestMethod]     public void ThenItShouldDisplay6()     {         Assert.AreEqual(6, this.calc.Result);     }      [TestMethod]     public void ThenTheCalculatorShouldNotBeNull()     {         Assert.IsNotNull(this.calc);     } }  public abstract class with_calculator : SpecificationContext {     protected Calculator calc;      public override void Given()     {         this.calc = new Calculator();     } }  public abstract class SpecificationContext {     [TestInitialize]     public void Init()     {         this.Given();         this.When();     }      public virtual void Given(){}     public virtual void When(){} }  public class Calculator {     public int Result { get; private set; }     public void Add(int p, int p_2)     {         this.Result = p + p_2;     } } 

Answer 2

Mark Nijhof has an example of doing Given-When-Then style testing with NUnit in his Fohjin.DDD github repository.

Here's an excerpt from the example referenced above:

public class When_registering_an_domain_event : BaseTestFixture<PreProcessor> {     /* ... */      protected override void When()     {         SubjectUnderTest.RegisterForPreProcessing<ClientMovedEvent>();         SubjectUnderTest.Process();     }      [Then]     public void Then_the_event_processors_for_client_moved_event_will_be_registered()     {         IEnumerable<EventProcessor> eventProcessors;         EventProcessorCache.TryGetEventProcessorsFor(typeof(ClientMovedEvent), out eventProcessors);         eventProcessors.Count().WillBe(1);     } } 

And you can see the Given in the base class implementation:

[Given] public void Setup() {     CaughtException = new NoExceptionWasThrownException();     Given();      try     {         When();     }     catch (Exception exception)     {         CaughtException = exception;     }     finally     {         Finally();     } }