Question

I have a class hierachy like this

public class A
{
    protected class B 
    {
        String Name { get; set; }
    }

    protected class C : KeyedCollection<String, B> 
    {
        // ...
    }

    protected C Collection { get; }

    // ...

    public A Copy () 
    {
        // Creates a deep copy of this instance.
    }
}

Now I’d like to write a unit test to compare if two instances of A have the same items B inside the property KeyedCollection. However, I’m not being able to perform a foreach loop into the A instances. What I had tried,

[TestClass]
public class TestClass
{
    public void ATest()
    {
        A original = new A();
        A copy = A.Copy();

        // ...

        A_Accessor originalAccessor = A_Accessor.AttachShadow(original);
        A_Accessor copyAccessor = A_Accessor.AttachShadow(copy);

        foreach(var originalItem in originalAccessor.Collection)
        {
            var copyItem = copyAccessor[originalItem.Name];
            Assert.AreEqual(originalItem, copyItem);
        }
    }
}

This code doesn’t even compile because the C class accessor doesn’t implements the IEnumerable interface (it doesn’t implement any interface from KeyedCollection class). Does anyone have an idea about how can I overcome this issue?

The error message I’m getting is

foreach statement cannot operate on variables of type ‘C’ because ‘A_Accessor.C’ does not contain a public definition for ‘GetEnumerator’

Answer 1

I just tried to compile your example: As expected I got an Error

Inconsistent accessibility: field type 'A.C' is less accessible than field 'A.Collection'.

Basically that means that you cannot declare a protected property using a private type. So it’s not a problem with your test code but with the code to be tested …

EDIT

You could use originalAccessor.Collection.Target and cast it to ICollection. Of course you can only enumerate over objects in this case, so you’ll have to cast each item again:

foreach (var item in (originalAccessor.Collection.Target as ICollection)) {
   A_Accessor.B casted = A_Accessor.B.AttachShadow(item);
   var copyItem = copyAccessor[casted.Name];
   Assert.AreEqual(casted, copyItem);
}