James McCaffrey: November, 2009

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November 22

Testing WCF Services using TCP Sockets

Over the past few days I've been looking at testing WCF services using a network socket based approach. I got a proof-of-concept demo program up and running. As usual, there were several glitches along the way. The key to resolving most of these glitches was to examine network traffic between a WCF service and a client, using a traffic examination tool. I used Fiddler, which has come in handy many times. See screenshot below. In a larger perspective, software testing is often all about understanding some software system. Once a system is fully understood, testing the system manually or programmatically usually comes pretty easily (relatively anyway). I am writing up an article on the technique of testing WCF services using sockets for MSDN Magazine and I'm happy with the way it is going.

11:55 AM | Add a comment | Permalink | Blog it | Software Test Automation

November 16

Programmatically Intercepting WCF Messages

Suppose you are testing a WCF (Windows Communication Foundation) service. In some situations you may want to view the low level traffic between a WCF client and the service. The easiest way to do this in general is to use a network analyzer such as netmon and capture the traffic as the client sends a request and receives a response. However in some test automation situations you may want to programmatically capture WCF traffic. There are several good blog posts on this topic but I couldn't find a complete end-to-end example so I experimented and came up with an example of how to do this.

First, let's assume we have a WCF service name MathService running in either a Console host, or in a Windows Service host, or in an IIS host:

[ServiceContract]
public interface IMathService
{
[OperationContract]
double Sum(double x, double y);
}

public class MathService : IMathService
{
public double Sum(double x, double y)
{
double answer = x + y;
return answer;
}
}

To programmatically capture WCF traffic you can first create a Console Application client like so:

EndpointAddress epAddress = new
EndpointAddress("http://machine:8000/MyWCFMathService/Service/MathService");

MathServiceClient sc = new MathServiceClient(new WSHttpBinding(), epAddress);
// wire up traffic interceptor here in a moment

Console.Write("\nEnter a number: ");
double x = double.Parse(Console.ReadLine());
Console.Write("Enter another: ");
double y = double.Parse(Console.ReadLine());

Console.WriteLine("\nSending " + x + " and " + y + " to Sum in WCF Math Service");
double ans = sc.Sum(x, y);
Console.WriteLine("\nThe response was: " + ans);

Next you can add two classes to the client like so:

class MyClientMessageInspector : IClientMessageInspector
{
public void AfterReceiveReply(ref System.ServiceModel.Channels.Message reply, object correlationState)
{
Console.WriteLine("\n\n" + reply.ToString());
}

public object BeforeSendRequest(ref System.ServiceModel.Channels.Message request, System.ServiceModel.IClientChannel channel)
{
Console.WriteLine("\n\n" + request.ToString());
return null;
}
}

class MyEndpointBehavior : IEndpointBehavior
{
public void AddBindingParameters(ServiceEndpoint serviceEndpoint, System.ServiceModel.Channels.BindingParameterCollection bindingParameters)
{ }

public void ApplyClientBehavior(ServiceEndpoint serviceEndpoint, System.ServiceModel.Dispatcher.ClientRuntime behavior)
{
behavior.MessageInspectors.Add(new MyClientMessageInspector());
}

public void ApplyDispatchBehavior(ServiceEndpoint serviceEndpoint, EndpointDispatcher endpointDispatcher)
{ }

public void Validate(ServiceEndpoint serviceEndpoint)
{ }

}

And then you can wire up the two classes in the client like so:

sc.Endpoint.Behaviors.Add(new MyEndpointBehavior());

When you execute the Console Application client program, WCF traffic will be echoed to the shell as demonstrated in the partial screenshot below.

10:57 AM | Add a comment | Permalink | Blog it | Software Test Automation

November 07

Silverlight Application UI Test Automation

I have been looking at Silverlight lately and have been investigating how to create UI test automation for Silverlight applications. As far as I can tell so far, it looks like there are two main approaches. First, you can use the Microsoft UI Automation (MUIA) library to create C#, shell-based test automation. A second approach is to use JavaScript-to-Silverlight interoperability and create browser-based test automation. I haven't tried ether approach but I'm fairly confident I could work out the details. A third possibility is to somehow use Silverlight technology to create UI test automation for a Silverlight application. I'm not sure how this would work, or if the technique is even possible, but the idea sounds interesting.