Possible repo pattern question or how to create one mock instance form multiple mock instances?

Question

I'd like to test my logic which expects three different interfaces. How can I unite these, because I can't use mock methods while I have three instances. I guess I did something very wrong with the repositories but I have no idea. Thank you for your help!

    [Test]
    public void TestThatLogicABCWorks()
    {
        Mock<IRepositoryA> mockInstance1 = new Mock<IRepositoryA>();
        Mock<IRepositoryB> mockInstance2 = new Mock<IRepositoryB>();
        Mock<IRepositoryC> mockInstance3 = new Mock<IRepositoryC>();
        LogicABC logic = new LogicABC(mockInstance1.Object, mockInstance2.Object, mockInstance3.Object);
    }

Edit: i have three entity classes, 1 general repository and three entity specific repos. In logic I make queries including all three entities, which I reach as:

public class LogicABC : ILogic
{

    IRepository<A> ARepo; //generic repo
    IRepository<B> BRepo;
    IRepository<C> CRepo;

    public LogicABC(IARepository ARepo, IBRepository BRepo, ICRepository CRepo)
    {
        this.ARepo = ARepo; //entity specific repos
        this.BRepo = BRepo;
        this.CRepo = CRepo;
    }

    public LogicABC()
    {
        var Entity = new ABCEntities(); //context
        this.ARepo = new ARepository(Entity);
        this.BRepo = new BRepository(Entity);
        this.CRepo = new CRepository(Entity);
    }
    //queries
    public List<int> Query1()
    {
    var q1 = from x in CRepo.GetAll()
             select x.Id;
    return q1.ToList();
    }

I need to test these queries with mock. For example setup that logicABC.Query1() returns 1 and then verify it.

Answer 1

When testing a subject under test that has dependencies, the dependencies explicitly needed for the test to flow to complete should be provided.

In this case Query1() is only using ICRepository and has not shown any interaction with the other two dependencies. If that is truly the case then those other dependencies are not needed.

Based on the method under test the following assumptions are being made

public interface ICRepository : IRepository<C> {
    //...
}

and something similar for the other repositories IARepository and IBRepository.

public interface IRemository<TEntity> {
    IEnumerable<TEntity> GetAll();

    //...other members
}

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

    //...other members
}

So the test for Query1 could be done as follows.

[Test]
public void LogicABC_Query1_Should_Return_One_Id() {
    //Arrange
    int expected = 123456789;
    var items = new [] { new C { Id = expectedId } }

    Mock<IRepositoryC> mock = new Mock<IRepositoryC>();
    mock.Setup(_ => _.GetAll()).Returns(items);

    LogicABC logic = new LogicABC(null, null, mock.Object);

    //Act
    List<int> list = logic.Query1();

    //Assert

    mock.Verify(_ => _.GetAll(), Times.Once());

    //checking expected behavior - using FluentAssertions
    list.Should().HaveCount(1);

    int actual = list.First();

    actual.Should().Be(expected); // using FluentAssertions
}

The unit test above tests the expected behavior of one subject method. The same pattern can be done for other members of the class under test.

Answer 2

You need to mock methods in every repository mock, i.e. in mockInstance1, mockInstance2 and mockInstance3. After this you'll be able to verify behavior inside LogicABC by checking applied mocks for every repos

UPDATE:

Your test should look like this:

[Test]
public void TestThatLogicABCWorks()
{
    Mock<IRepositoryA> mockInstance1 = new Mock<IRepositoryA>();
    mockInstance1.Setup(foo => foo.Do()).Returns(() => 1);

    Mock<IRepositoryB> mockInstance2 = new Mock<IRepositoryB>();
    mockInstance2.Setup(boo => boo.Do2()).Returns(() => 2);

    Mock<IRepositoryC> mockInstance3 = new Mock<IRepositoryC>();
    mockInstance3.Setup(doo => doo.Do3()).Returns(() => 3);

    LogicABC logic = new LogicABC(mockInstance1.Object, mockInstance2.Object, mockInstance3.Object);

    logic.DoLogic();

    // do some asserts here
}