public async Task DeletePurchase_OutOfBounds()
        {
            // Arrange
            var repo = new FakePurchaseRepo(TestData.Purchases());
            var productRepo = new FakeProductService(TestData.Products());
            using (var controller = new PurchasesController(repo, productRepo, null, null))
            {
                var purchaseId = -6;

                // Act
                var result = await controller.DeleteConfirmed(purchaseId);

                // Assert
                Assert.IsInstanceOfType(result, typeof(BadRequestResult));
            }
        }
        public async Task DeletePurchase_Success()
        {
            // Arrange
            var repo = new FakePurchaseRepo(TestData.Purchases());
            var productRepo = new FakeProductService(TestData.Products());
            using (var controller = new PurchasesController(repo, productRepo, null, null))
            {
                var purchaseId = 1;

                // Act
                await controller.DeleteConfirmed(purchaseId);

                // Assert
                var purchase = await controller.Details(purchaseId);
                Assert.IsInstanceOfType(purchase.Result, typeof(NotFoundResult));
            }
        }