Can I use Moq in this situation?

Question

What possible work-around do I have for mocking this object using Moq. The error message returned is: "Invalid setup on a non-virtual (overridable in VB) member: p => p.Certificate.SubjectName.Name"

        var st = new Mock<X509SecurityToken>();
        st.SetupGet(p => p.Certificate.SubjectName.Name).Returns("test1");
        var target = new X509IssuerNameRegistry("test1", "test2");

        var actual = target.GetIssuerName(st.Object);

        Assert.AreEqual<string>("test1", actual, "Actual security token did not equal expected security token");

Note: I am trying to Mock X509SecurityToken. Here is the class under test:

public class X509IssuerNameRegistry : IssuerNameRegistry { readonly List _trustedSubjectNames = new List();

public X509IssuerNameRegistry(params string[] trustedSubjectNames)
{
    _trustedSubjectNames = new List<string>(trustedSubjectNames);
}

public override string GetIssuerName(SecurityToken securityToken)
{
    var x509Token = securityToken as X509SecurityToken;
    if (x509Token != null)
    {
        if (_trustedSubjectNames.Contains(x509Token.Certificate.SubjectName.Name))
        {
            return x509Token.Certificate.SubjectName.Name;
        }
    }
    throw new SecurityTokenException("Untrusted issuer.");
}

}

Any work-rounds for this (using Moq) or should I look to another mocking framework to accomplish this?

There is no usage if st object in your code snippet, though dynamic proxy libraries might be helpful in this case — Jahan Zinedine, Sep 17 '12 at 04:35

Joachim Isaksson · Answer 1 · 2012-09-17T04:46:28.510

No, Moq (just like any inheriting class) cannot override non-virtual methods, so unless you can make Name a virtual property (by changing or wrapping the class), it cannot be mocked by Moq.

I'd suggest that you if possible change your property to be virtual, since that will allow you to use any mocking framework. As far as I know there are only 3 that can mock non virtual methods, none of them free;

Microsoft Fakes that comes with VS2012 (Ultimate only I believe)
Typemock Isolator.
Telerik JustMock (not the free version).

score 0 · Answer 2 · answered Sep 17 '12 at 04:34

You could look for some framework that allows you to 'hack' the code that cannot be mocked simply (i.e. does not contain virtual methods/is not an interface), but that could be overkill (and some options are not free like TypeMock Isolator for example).

An easier approach might be to abstract X509SecurityToken, for example:

interface ISecurityToken
{
    string SubjectName { get; }
    // ...
}

Then, implement a wrapper which also implements interface specified above:

class SecurityToken : ISecurityToken
{
    X509SecurityToken token;
    public SecurityToken(X509SecurityToken token)
    {
        this.token = token;
    }
    public string SubjectName { get { return token.SubjectName.Name; } }
}

Then, throughout your code, you should use ISecurityToken interface instead of X509SecurityToken, which would be rather straightforward to mock.

solving this problem was my original intent with this post. I updated the original post with the code under test. How to design around this when I am overriding a base class method from the BCL? — Pete Maroun, Sep 17 '12 at 19:08

Can I use Moq in this situation?

2 Answers2