Creating a wrapper class to use for mocking that uses IDisposable

Question

I have a third party component that I am trying to write unit tests around. The problem is that I can't mock the object and there is no interface.

I decided to create an interface and a wrapper class calling into the code for the sake of mocking. I looked into the class definition that is generated by Visual Studio using the meta data and noticed a few things:

• The class has two constructors (one takes a parameter)
• The class inherits from IDisposable

My questions are:

1. Does my implementation below look right?
2. Did I handle the IDisposable implementation correctly in the proxy class?
3. Do I need the second constructor in the proxy class since the interface does not support constructor definitions? I use dependency injection in my code and I assume unless I tell my DI framework to use the second constructor I don't really need it but I am not sure.

The meta data looks like (slimmed down version):

public class PopClient : IDisposable
{
    public const int DefaultPort = 110;
    public const int DefaultSSLPort = 995;

    public PopClient();
    public PopClient(AddressFamily addressFamily);
    public bool HasTimeStamp { get; }
    public List<string> Capability();
    public void Connect(string host);
    protected override void GetServerGreeting();
}

Based on the meta data, my interface looks like (after removing methods/properties/access modifiers that are invalid in an interface definition):

public interface IPopClient : IDisposable
{
    bool HasTimeStamp { get; }
    List<string> Capability();
    void Connect(string host);
    void ConnectSSL(string host);
}

Based on the interface, I then created the wrapper class:

public class PopClientProxy : IPopClient
{
    private readonly Pop3 pop3;

    public PopClientProxy()
        this.pop3 = new Pop3();

    public PopClientProxy(AddressFamily addressFamily)
        this.pop3 = new Pop3(addressFamily);

    public bool HasTimeStamp
        get { return pop3.HasTimeStamp; }

    public List<string> Capability()
        return pop3.Capability();

    public void Connect(string host)
        pop3.Connect(host);

    public void Dispose()
    {
        if (pop3 != null)
            pop3.Dispose();
    }
}

Answer 1

Congratulations! You have successfully utilized the object-oriented design pattern known as the Adapter Pattern. I think that looks perfectly good. Though, I wouldn't check pop3 for null in the Dispose() method as it will be guaranteed to not be null by the constructors and the readonly field modifier:

public void Dispose()
{
    pop3.Dispose();
}