使用Moq設置並驗證表達式

Question

有沒有辦法設置和驗證使用Moq表達式的方法調用？

第一次嘗試是我想讓它工作的那個，而第二次嘗試是讓Assert部分工作的“補丁”（驗證部分仍然失敗）

string goodUrl = "good-product-url";

[Setup]
public void SetUp()
{
  productsQuery.Setup(x => x.GetByFilter(m=>m.Url== goodUrl).Returns(new Product() { Title = "Good product", ... });
}

[Test]
public void MyTest()
{
  var controller = GetController();
  var result = ((ViewResult)controller.Detail(goodUrl)).Model as ProductViewModel;
  Assert.AreEqual("Good product", result.Title);
  productsQuery.Verify(x => x.GetByFilter(t => t.Url == goodUrl), Times.Once());
}

在Assert測試失敗並拋出空引用異常，因為從不調用方法GetByFilter。

如果相反我使用它

[Setup]
public void SetUp()
{
  productsQuery.Setup(x => x.GetByFilter(It.IsAny<Expression<Func<Product, bool>>>())).Returns(new Product() { Title = "Good product", ... });
}

測試通過了Assert部分，但這次是驗證失敗，說它從未被調用過。

有沒有辦法用特定的表達式設置方法調用，而不是使用泛型It.IsAny<>() ？

更新

我在評論中也嘗試了UfukHacıoğulları的建議並創建了以下內容

Expression<Func<Product, bool>> goodUrlExpression = x => x.UrlRewrite == "GoodUrl";

[Setup]
public void SetUp()
{
  productsQuery.Setup(x => x.GetByFilter(goodUrlExpression)).Returns(new Product() { Title = "Good product", ... });
}

[Test]
public void MyTest()
{
  ...
  productsQuery.Verify(x => x.GetByFilter(goodUrlExpression), Times.Once());
}

但是我得到了一個空引用異常，就像在第一次嘗試中一樣。

我的控制器中的代碼如下

public ActionResult Detail(string urlRewrite)
{
  //Here, during tests, I get the null reference exception
  var entity = productQueries.GetByFilter(x => x.UrlRewrite == urlRewrite);
  var model = new ProductDetailViewModel() { UrlRewrite = entity.UrlRewrite, Culture = entity.Culture, Title = entity.Title };
  return View(model);
}

Answer 1

以下代碼演示了如何在此類方案中進行測試。 一般的想法是你對“真實”數據執行傳入的查詢。 這樣，您甚至不需要“驗證”，就好像查詢不對，它將無法找到數據。

修改以滿足您的需求：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using Moq;
using NUnit.Framework;

namespace StackOverflowExample.Moq
{
    public class Product
    {
        public string UrlRewrite { get; set; }
        public string Title { get; set; }
    }

    public interface IProductQuery
    {
        Product GetByFilter(Expression<Func<Product, bool>> filter);
    }

    public class Controller
    {
        private readonly IProductQuery _queryProvider;
        public Controller(IProductQuery queryProvider)
        {
            _queryProvider = queryProvider;
        }

        public Product GetProductByUrl(string urlRewrite)
        {
            return _queryProvider.GetByFilter(x => x.UrlRewrite == urlRewrite);
        }
    }

    [TestFixture]
    public class ExpressionMatching
    {
        [Test]
        public void MatchTest()
        {
            //arrange
            const string GOODURL = "goodurl";
            var goodProduct = new Product {UrlRewrite = GOODURL};
            var products = new List<Product>
                {
                    goodProduct
                };

            var qp = new Mock<IProductQuery>();
            qp.Setup(q => q.GetByFilter(It.IsAny<Expression<Func<Product, bool>>>()))
              .Returns<Expression<Func<Product, bool>>>(q =>
                  {
                      var query = q.Compile();
                      return products.First(query);
                  });

            var testController = new Controller(qp.Object);

            //act
            var foundProduct = testController.GetProductByUrl(GOODURL);

            //assert
            Assert.AreSame(foundProduct, goodProduct);
        }
    }
}