def test_interfaces(self): self.assertTrue(verifyObject(ITask, Task())) self.assertTrue(verifyObject(IValidatedTask, Estimation())) self.assertTrue(verifyObject(IPaidTask, Invoice())) self.assertTrue(verifyObject(IPaidTask, CancelInvoice())) self.assertTrue(verifyObject(IInvoice, Invoice())) self.assertTrue(verifyObject(IInvoice, CancelInvoice()))