I'm trying to mock out the System.net.Sockets.Socket class in C# - I tried using NUnit mocks but it can't mock concrete classes. I also tried using Rhino Mocks but it seemed to use a real version of the class because it threw a SocketException when Send(byte[]) was called. Has anyone successfully created and used a Socket mock using any mocking framework?
+7
A:
Whenever I run into these kinds of problems with Moq I end up creating an interface to abstract away the thing I can't mock.
So in your instance you might have an ISocket interface that implements the Send method. Then have your mocking framework mock that instead.
In your actual code, you'd have a class like this
public class MySocket : ISocket
{
System.Net.Sockets.Socket _socket;
public void MySocket(System.Net.Sockets.Socket theSocket)
{
_socket = theSocket;
}
public virtual void Send(byte[] stuffToSend)
{
_socket.Send(stuffToSend);
}
}
Not sure if that meets your needs, but it's an option.
thinkzig
2009-08-12 00:07:05
You should consider making the send method virtual too :)
Chris Missal
2009-08-12 11:58:41
Good call. Edited to make Send method virtual.
thinkzig
2009-08-12 13:19:29
But don't stop there. Rather than just echoing the external API, write an interface that describes what your code wants from the communication layer. This might mean that it accepts more structured input, rather than bytes. Or something else, it depends on the context.
Steve Freeman
2009-09-07 11:45:11
But, if you make this interface more complicated you will need to unit test it, which will mean needing to mock the internal components again... kind of defeats the purpose.
Mystere Man
2009-12-28 17:51:22
Steve Guidi
2009-12-28 18:18:03
Modifying the interface is a perfectly acceptable thing to do. It's called the Adapter pattern. And, yes, the code inside the adapter (that translates the structured input into the byte array) will need to be unit tested. But, in reality, that code should not be a part of the adapter class. Rather, it should be in a converter class with its own unit tests. The adapter class, then, becomes a client of the tested code. (Remember, it's only necessary to test that which might fail. The single line of code in the adapter to call the converter is maybe not worth the effort.)
Alan Ridlehoover
2010-01-23 07:07:14
A:
You'd better to create an interface and mock it in your test, and implement a wrapper class in your code, that forward all method calls to .NET socket as thinkzig said. Look at this link, it's same issue: http://stackoverflow.com/questions/1087351/how-do-you-mock-out-the-file-system-in-c-for-unit-testing
Tiendq
2009-08-12 04:57:44
+2
A:
The reason you get a SocketException when you call the Send method is because Send is not an overridable method. For RhinoMocks to be able to mock the behavior of a property or method, it has to either be defined in an interface (which we then create our mock off) or is overridable.
Your only solution to this is to create a mockable wrapper class (as suggested by thinkzig).
jpoh
2009-08-12 09:36:10
+1
A:
I've created an example console application using the method thinkzig suggests (an adapter class for Socket). It uses RhinoMocks and NUnit. You can download it here: How to mock System.Net.Sockets.Socket.
StefanMacke
2009-12-28 17:15:04