c# - Moq, SetupGet, Mocking a property

Question

I'm trying to mock a class, called UserInputEntity, which contains a property called ColumnNames: (it does contain other properties, I've just simplified it for the question)

namespace CsvImporter.Entity
{
    public interface IUserInputEntity
    {
        List<String> ColumnNames { get; set; }
    }

    public class UserInputEntity : IUserInputEntity
    {
        public UserInputEntity(List<String> columnNameInputs)
        {
            ColumnNames = columnNameInputs;
        }

        public List<String> ColumnNames { get; set; }
    }
}

I have a presenter class:

namespace CsvImporter.UserInterface
{
    public interface IMainPresenterHelper
    {
        //...
    }

    public class MainPresenterHelper:IMainPresenterHelper
    {
        //....
    }

    public class MainPresenter
    {
        UserInputEntity inputs;

        IFileDialog _dialog;
        IMainForm _view;
        IMainPresenterHelper _helper;

        public MainPresenter(IMainForm view, IFileDialog dialog, IMainPresenterHelper helper)
        {
            _view = view;
            _dialog = dialog;
            _helper = helper;
            view.ComposeCollectionOfControls += ComposeCollectionOfControls;
            view.SelectCsvFilePath += SelectCsvFilePath;
            view.SelectErrorLogFilePath += SelectErrorLogFilePath;
            view.DataVerification += DataVerification;
        }


        public bool testMethod(IUserInputEntity input)
        {
            if (inputs.ColumnNames[0] == "testing")
            {
                return true;
            }
            else
            {
                return false;
            }
        }
    }
}

I've tried the following test, where I mock the entity, try to get ColumnNames property to return a initialized List<string>() but it's not working:

    [Test]
    public void TestMethod_ReturnsTrue()
    {
        Mock<IMainForm> view = new Mock<IMainForm>();
        Mock<IFileDialog> dialog = new Mock<IFileDialog>();
        Mock<IMainPresenterHelper> helper = new Mock<IMainPresenterHelper>();

        MainPresenter presenter = new MainPresenter(view.Object, dialog.Object, helper.Object);

        List<String> temp = new List<string>();
        temp.Add("testing");

        Mock<IUserInputEntity> input = new Mock<IUserInputEntity>();

    //Errors occur on the below line.
        input.SetupGet(x => x.ColumnNames).Returns(temp[0]);

        bool testing = presenter.testMethod(input.Object);
        Assert.AreEqual(testing, true);
    }

The errors I get state that there are some invalid arguments + Argument 1 cannot be converted from string to

System.Func<System.Collection.Generic.List<string>>

Any help would be appreciated.

Answer 1

ColumnNames is a property of type List<String> so when you are setting up you need to pass a List<String> in the Returns call as an argument (or a func which return a List<String>)

But with this line you are trying to return just a string

input.SetupGet(x => x.ColumnNames).Returns(temp[0]);

which is causing the exception.

Change it to return whole list:

input.SetupGet(x => x.ColumnNames).Returns(temp);