c# - How can I use PrivateObject to access private members of both my class and its parent?

Question

I'm testing a class that is part of a hierarchy. I've been setting up my test classes with the object under test, and a PrivateObject to allow access to that object. I'm getting exceptions when I attempt to access private members of the parent class.

The only workaround I've found so far is to pass a PrivateType specifying the base class to the PrivateObject constructor, but then it doesn't work on private members of the subclass.

Is there some way I can do this, perhaps by using the binding flags parameter on the Get* methods of Private object?

I did try using the automatically-generated Accessor classes (right-click in the main class, Create Private Accessor). However, that's worse: It shows a property I can read, but it throws the same exception as PrivateObject does, and there's no other options I can use (binding flags or whatnot) to fix the exception.

Here's my sample test code. I'd like there to be some way to construct and use the PrivateObject to retrieve both fields.

public class BaseClass
{
    private int one = 1;
}

public class SubClass : BaseClass
{
    private int two = 2;
}

[TestClass]
public class UnitTest1
{
    BindingFlags flags = BindingFlags.FlattenHierarchy | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance;

    [TestMethod]
    public void TestMethod1()
    {
        SubClass test = new SubClass();
        PrivateObject priv = new PrivateObject(test);

        Assert.AreNotEqual<int>(0, (int)priv.GetFieldOrProperty("one", flags)); // System.MissingMethodException: Method 'PrivateObjectTester.SubClass.one' not found.
        Assert.AreNotEqual<int>(0, (int)priv.GetFieldOrProperty("two", flags));
    }

    [TestMethod]
    public void TestMethod2()
    {
        SubClass test = new SubClass();
        PrivateObject priv = new PrivateObject(test, new PrivateType(typeof(BaseClass)));

        Assert.AreNotEqual<int>(0, (int)priv.GetFieldOrProperty("one", flags));
        Assert.AreNotEqual<int>(0, (int)priv.GetFieldOrProperty("two", flags)); // System.MissingMethodException: Method 'PrivateObjectTester.BaseClass.two' not found.
    }
}

Answer 1

I didn't find the answer, so this is what I ended up doing. I created PrivateObjects for each level of the class's hierarchy, and I just need to be careful when writing test cases that I use the proper one.

public class BaseClass
{
    private int one = 1;
}

public class SubClass : BaseClass
{
    private int two = 2;
}

[TestClass]
public class UnitTest1
{
    [TestMethod]
    public void TestMethod()
    {
        SubClass test = new SubClass();
        PrivateObject privSub = new PrivateObject(test, new PrivateType(typeof(SubClass)));
        PrivateObject privBase = new PrivateObject(test, new PrivateType(typeof(BaseClass)));

        Assert.AreNotEqual<int>(0, (int)privBase.GetFieldOrProperty("one"));
        Assert.AreNotEqual<int>(0, (int)privSub.GetFieldOrProperty("two"));
    }
}