public void CanPurchase_PersonWitNoCreditPassesValidation_ReturnFalse() { MyLittleFakeValidator validator = new MyLittleFakeValidator(); validator.WillReturnIsValid = true; PersonLogicBTestable pl = new PersonLogicBTestable(validator); bool canPurchase = pl.CanPurchase(new Person()); Assert.IsFalse(canPurchase); }