具有多个签名的 Moq 规范模式接口实现

Question

I'm trying to setup two different mocked objects based on the inputs supplied.

The generic Interface definitions is as follows:

public interface ISpecification<T>
{
    Expression<Func<T, bool>> Criteria { get; }
    List<Expression<Func<T, object>>> Includes { get; }
    List<string> IncludeStrings { get; }
    Expression<Func<T, object>> OrderBy { get; }
    Expression<Func<T, object>> OrderByDescending { get; }

    int Take { get; }
    int Skip { get; }
    bool IsPagingEnabled { get; }
}

Then an implementing class which has three methods and derives from an intermediary base class.

public sealed class WindFarmsSpecification : BaseSpecification<WindFarm>
{
    public WindFarmsSpecification()
        : base(null)
    {
        this.AddInclude("Submissions");
        this.ApplyOrderBy(s => s.Name);
    }

    public WindFarmsSpecification(string name)
        : base(s => s.Name.Contains(name))
    {
        this.AddInclude("Submissions");
        this.ApplyOrderBy(s => s.Name);
    }

    public WindFarmsSpecification(Guid guidId)
        : base(s => s.GuidId == guidId)
    {
        this.AddInclude("Submissions");
    }
}

Basic mocking of this is a simple as:

mock.Setup(m => m.ListAsync(It.IsAny<ISpecification<WindFarm>>()))
            .Returns(() =>
            {
                var windFarms = new List<WindFarm>
                {
                    testWindFarm1
                };

                return Task.FromResult((IReadOnlyList<WindFarm>)windFarms);
            });

Which is OK, as long as I don't care what get returns and abstracts away the details. However, I do now need to care about this.

How do I modify the moq It.IsAny<ISpecification<WindFarm>>() so that I can differentiate between

public WindFarmsSpecification()

and

public WindFarmsSpecification(string name)

Answer 1

It is not explicitly possible to know which constructor was used. But it can be implied based on what is populated in the parameter according to what was shown in the example constructors.

Capture the passed parameter and use as needed

For example

mock
    .Setup(_ => _.ListAsync(It.IsAny<ISpecification<WindFarm>>()))
    .ReturnsAsync((ISpecification<WindFarm> spec) => {
        //access passed argument
        var criteria = spec.Criteria;

        //use expression to filter a mock list            
        var result = somelist.Where(criteria).OrderBy(spec.OrderBy).ToList();    

        return (IReadOnlyList<WindFarm>)result;
    });