How to verify that generic private method was called?

public class Foo
{
    public static void CallWithInt()
    {
        Bar<Int32>();
    }

    private static void Bar<T>()
    {
    }
}

[TestMethod]
public void TestMethod1()
{
    bool wasCalledWithInt = false;
    bool wasCalledWithChar = false;

    Isolate.NonPublic.WhenCalled(typeof(Foo) , "Bar").DoInstead(context =>
        {
            Type[] genericArguments = context.Method.GetGenericArguments();
            if (genericArguments[0] == typeof(Int32))
            {
                wasCalledWithInt = true;
            }
            if (genericArguments[0] == typeof(char))
            {
                wasCalledWithChar = true;
            }

            context.WillCallOriginal();
        });

    Foo.CallWithInt();

    Assert.IsTrue(wasCalledWithInt);
    Assert.IsFalse(wasCalledWithChar);
}

// in code under test
TestPrivates.PrivateStaticGenericMethod<int>()
// in test code.
Isolate.Verify.NonPublic.WasCalled(typeof (TestPrivates), "PrivateStaticGenericMethod", typeof(int));