Tasc Unit Testing Pattern

Often when unit testing you need a concrete class that is a stub for an abstract class you are testing. However, instead of creating a class strictly for the stub purpose you can use your test class and thus have less artifacts to maintain. The class is a [T]est [A]nd [S]tub [C]lass.

Consider an abstract class that generates an id on first access if it has not previously been set:

public abstract class DomainBase
{
 private Guid _id;
 public Guid Id
 {
   get
   {
     if (_id==Guid.Empty)
     {
       _id=Guid.NewGuid();
     }
     return _id;
   }
   set { _id = value }
 }
}

The test then becomes:

[TestFixture]
public class DomainBaseTasc : DomainBase
{
 [Test]
 public void EnsureIdIsGenerated()
 {
   DomainBaseTasc tasc = new DomainBaseTasc();
   Assert.IsTrue(tasc.Id!=Guid.Empty);
 }

 [Test]
 public void EnsureIdIsOnlyGeneratedOnFirstAccess()
 {
   DomainBaseTasc tasc = new DomainBaseTasc();
   Assert.IsTrue(tasc.Id==tasc.Id);
 }
}