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);
        }