Liskov principle and unittest

[mta`chrono]

class Superclass
{
     abstract int do_some_stuff();
     abstract int do_some_other_stuff();
}

class Foo1 : Superclass....
class Foo2 : Superclass....
class Foo3 : Superclass....


unittest
{
      // get an instance of all classes
      Superclass[] instances = [new Foo1(), new Foo2(), new Foo3()];

      // test their behavoir
      foreach(instance; instances)
      {
           assert(instance.do_some_stuff() > 0, "whoops!");
           assert(instance.do_some_other_stuff() < 100, "whoops!");
      }
}