public void DeleteInvoiceHeaderFromDatabase() { IInvoice invoiceHeader = new Invoice { CustomerId = 1, SupplierId = 2, InvoiceNumber = 10 }; IInvoiceDao invoiceDao = new InvoiceDao(_sqlConnection); invoiceDao.Write(invoiceHeader); invoiceDao = new InvoiceDao(_sqlConnection); var rowsAffected = invoiceDao.Delete(invoiceHeader); Assert.IsTrue(rowsAffected == 1); }