Setup and verify expression with Moq

Question

Is there a way to setup and verify a method call that use an Expression with Moq?

The first attempt is the one I would like to get it to work, while the second one i

Answer 1

The following code demonstrates how to test in such scenarios. The general idea is that you execute the passed in query against a "real" data. That way, you don't even need "Verify", as if the query is not right, it will not find the data.

Modify to suit your needs:

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);
        }
    }
}