如何使用 Moq 模拟带有 lambda 表达式的服务调用

Question

I'm using Moq to try to mock a method that has a lambda expression as its optional parameter and calls a database.

This is the real method that I am trying to mock

public IQueryable<T> AllSearchBy<T>(params Expression<Func<T, bool>>[] search) where T : class
    {
        IQueryable<T> result = _context.Set<T>();

        foreach (var item in search)
        {
            result = result.Where(item);
        }

        return result;
    }

Here is my moq repository set up

var mockRepository = new Mock<IRepository>();

var rateEndHsbSlcTable = new List<Rate_End_HSB_SLC>
        {
            new Rate_End_HSB_SLC
            {
                Limit = 10000,
                DwellingAgeMin = 0,
                DwelilngAgeMax = 25,
                Premium = 22M
            },
            new Rate_End_HSB_SLC
            {
                Limit = 10000,
                DwellingAgeMin = 26,
                DwelilngAgeMax = 50,
                Premium = 45M
            }
        };

mockRepository.Setup(m => m.AllSearchBy(It.IsAny<Expression<Func<Rate_End_HSB_SLC, bool>>>()))
                      .Returns((Expression<Func<Rate_End_HSB_SLC, bool>> predicate) => rateEndHsbSlcTable.Where(predicate.Compile()).AsQueryable());



IRateServices rateService = new RateServices(mockRepository.Object, new HelperServices(mockRepository.Object));

And here is the call in code that I'm testing that gives me an error (I replaced the variables with hard values for simplicity)

var test = _repository.AllSearchBy<Rate_End_HSB_SLC>(x => x.Limit == 10000 && x.DwellingAgeMin <= 19 && x.DwelilngAgeMax >= 19);

This compiles, but give me the below exception when it runs

System.ArgumentException: Object of type 'System.Linq.Expressions.Expression 1[System.Func 2[Twico.DataAccess.Rate_End_HSB_SLC,System.Boolean]][]' cannot be converted to type 'System.Linq.Expressions.Expression 1[System.Func 2[Twico.DataAccess.Rate_End_HSB_SLC,System.Boolean]]'.

I suspect the issue is in my setup and return not being in the correct type.

Any ideas on what I'm doing wrong?

Edit: using ibebbs answer, I got it to work with this syntax!

mockRepository.Setup(m => m.AllSearchBy(It.IsAny<Expression<Func<Rate_End_HSB_SLC, bool>>[]>()))
                      .Returns((Expression<Func<Rate_End_HSB_SLC, bool>>[] predicates) => predicates.Aggregate(rateEndHsbSlcTable, (source, predicate) => source.Where(predicate.Compile()).ToList()).AsQueryable());

Answer 1

Quick look over the code shows that the AllSearchBy is expecting an array of Expression<Func<T, bool>> but your setup specifies a single expression.

Perhaps try something like this?

mockRepository
  .Setup(m => m.AllSearchBy(It.IsAny<Expression<Func<Rate_End_HSB_SLC, bool>>[]>()))
  .Returns(predicates => predicates
    .Aggregate(
      rateEndHsbSlcTable, 
      (source, predicate) => source.Where(predicate.Compile())).AsQueryable());