How do I mock nested service call using moq

Question

I have a statement similar to

var res = _serviceA.MethodA(() => _serviceB.MethodB(new objectA(){ Id = 10 }) 

which is being called twice in the method and also the response changes based on the value of Id, hence I need to setup the response such that a different object is returned based on the the Id value.

Current mock:

_serviceAMock.Setup(x => x.MethodA(It.IsAny<Func<ResponseObject>>())).Return(responseOfTypeResponseObject);

Is it possible to achieve this using moq? if yes how? I was able to mock MethodA and get the response but I couldn't figure out how to mock it such that the result varies based on the Id value.

Mocking Class:

public class ClassToTest
    {
        private readonly IServiceA<int> _serviceA;
        private readonly IServiceB _serviceB;

        public ClassToTest(IServiceA<int> serviceA, IServiceB serviceB)
        {
            _serviceA = serviceA;
            _serviceB = serviceB;
        }

        public void MethodToTest()
        {
            var res = _serviceA.MethodA(() => _serviceB.MethodB(new ObjectA() { Id = 10 }));
        }

    }

Supporting objects:

public class ObjectA
{
    public int Id { get; set; }
}

public interface IServiceB
{
    int MethodB(ObjectA objectA);
}

public interface IServiceA<T>
{
    T MethodA(Func<T> handler);
}

Answer 1

That worked for me:

using FluentAssertions;
using Moq;

namespace MockDifferentResult;

public class Tests
{
    [Test]
    public void Test1()
    {
        // Arrange
        var serviceBMock = new Mock<IServiceB>();
        serviceBMock
            .Setup(service => service.MethodB(It.Is<ObjectA>(a => a.Id == 10)))
            .Returns(1);
        serviceBMock
            .Setup(service => service.MethodB(It.Is<ObjectA>(a => a.Id == 20)))
            .Returns(2);
        var serviceAMock = new Mock<IServiceA<int>>();
        serviceAMock
            .Setup(service => service.MethodA(It.IsAny<Func<int>>()))
            .Returns<Func<int>>(handler => handler());
        var testee = new ClassToTest(serviceAMock.Object, serviceBMock.Object);
        
        // Act
        testee.MethodToTest();
        
        // Assert
        testee.Res1.Should().Be(1);
        testee.Res2.Should().Be(2);
    }
}

public class ClassToTest
{
    private readonly IServiceA<int> _serviceA;
    private readonly IServiceB _serviceB;
    
    public int Res1 { get; private set; }
    public int Res2 { get; private set; }

    public ClassToTest(IServiceA<int> serviceA, IServiceB serviceB)
    {
        _serviceA = serviceA;
        _serviceB = serviceB;
    }

    public void MethodToTest()
    {
        Res1 = _serviceA.MethodA(() => _serviceB.MethodB(new ObjectA { Id = 10 }));
        Res2 = _serviceA.MethodA(() => _serviceB.MethodB(new ObjectA { Id = 20 }));
    }
}

public class ObjectA
{
    public int Id { get; set; }
}

public interface IServiceB
{
    int MethodB(ObjectA objectA);
}

public interface IServiceA<T>
{
    T MethodA(Func<T> handler);
}

Please give it a try and see if it suffices your needs.