ArgumentException when creating new Faker on derived class with property using the 'new' modifier

[carleberg]

I stumbled upon this issue when doing refactoring of our class hierarchies. The problem occurred when we introduced a few new base classes that have derived subclasses that use the 'new' modifier on a property.

We are running this on .NET 4.6.2 and Bogus 12.0.1. I have managed to reproduce the issue with the unit test below.

    [TestClass]
    public class BogusTest
    {
        [TestMethod]
        public void TestMethod1()
        {
            //Works
            var baseA = new Faker<BaseA>();

            //Throws System.ArgumentException: 'An item with the same key has already been added.'
            var derivedA = new Faker<DerivedA>();
        }
    }

    class BaseA
    {
        public BaseB SomeProp { get; set; }
    }

    class DerivedA : BaseA
    {
        public new DerivedB SomeProp { get; set; }
    }

    class BaseB
    {
        public int Value { get; set; }
    }

    class DerivedB : BaseB
    {
        public new int Value { get; set; }
    }

[bchavez]

Hi @carleberg ,

Thanks very much for reporting this. I think I might have forgotten a binding flag that caused multiple properties (with the same name/key) being added into a dictionary.

I think I've made the correct fix and here's the passing unit test:

public class Issue70 : SeededTest
{
    [Test]
    public void should_be_able_to_create_derrived_faker_with_class_hierarchy()
    {
        var baseBFaker = new Faker<BaseB>()
            .RuleFor(b => b.Value, f => f.Random.Int(1,5));

        var derivedBFaker = new Faker<DerivedB>()
            .RuleFor(b => b.Value, f => f.Random.Int(6,10)); ;

        //Works
        var baseAFaker = new Faker<BaseA>()
            .RuleFor(a => a.SomeProp, () => baseBFaker.Generate()); ;

        //Threw System.ArgumentException: 'An item with the same key has already been added.'
        var derivedAFaker = new Faker<DerivedA>()
            .RuleFor(da => da.SomeProp, () => derivedBFaker.Generate());


        DerivedA derivedA = derivedAFaker.Generate();

        derivedA.SomeProp.Value.Should().BeInRange(6,10);
        BaseA baseA = derivedA;
        baseA.SomeProp.Should().BeNull();
    }
}

Let me know if the unit test above looks correct and I'll run a new release with the fix.

Thanks,
💨 🚶 "Bubbles of gas in my brain... Send me off balance, it's not enough"

[bchavez]

Hi @carleberg ,

Bogus v15.0.1 is now available and should hopefully fix your issue. Let me know. Feel free to re-open the issue if you continue to have problems.

Thanks,
Brian

🚶 😎 "So don't delay... act now supplies are running out..."

[carleberg]

It works great, thanks a lot for your quick response!