Hi, You probably misunderstood the task.
On the first part I have to make a class named BlankCell which is a > subclass of TestCase. > You had to create the class *BlankCellTestCase* (not BlankCell) which is a subclass of *TestCase*. BlankCell and BlankCellTestCase are two different classes. -BlankCell is a class that represents a model of an empty cell (its size, segments etc.) -BlankCellTestCase is basically a class that helps you to control (and test) methods that you have on BlankCell class. But when you are on the MirrorCell part BlankCell must be a subclass of > Cell. > Cell class is an abstract, which is a superclass for following classes: BlankCell, MirrorCell, TargetCell. It provides some basic behavior or properties for BlankCell, MirrorCell, TargetCell, which all of them have in common But then the tests will fail because should: cannot be found. > Sure it fails. in order to use *should:* the class BlankCellTestCase has to be a subclass of TestCase. But it is recommended to use *assert:* instead of *should:* The manual says nothing about that the new class Cell must be a part of > TestCase. > Cell has to be a subclass of an Object. Cheers, Mark
