I had the genius idea to create a test service implementation to test our client services. I would use the test service as a fake stand-in for the real services as the real services are managed by third parties. Imagine wanting to test your client calls to the Twitter API without having to get burned by the firewall trying to make a call to an external service.

As usual, it ends up that I am not a genius and my idea is not unique. There isn’t a lot of info on how to do it in the .Net stack, but I did find some discussions on a few Bings. I ended up using wsdl.exe to extract a service interface from the WSDL and implementing the WSDL with simple ASMX files. I won’t go into the details, but this is basically what I did:

1. Get a copy of the WSDL and XSD from the actual service.
2. Tell wsdl.exe where you stored these files and what you want to do, which is generate a service interface

   wsdl.exe yourFile.wsdl yourfile.xsd /l:CS /serverInterface

3.  Then implement the interface as an ASMX (you could do WCF, but I was in a hurry)
4. Lastly, point your client to your fake service

In your implementation, you can return whatever you are expecting in your tests. You can also capture the HTTP Messages. Actually, the main reason I wanted to do this was to figure out if my SOAP message was properly formatted and I didn’t want to go through all of the trace listener diagnostics configuration with a Fiddler port capture crap. There may be easier ways to do this and even best practices around testing service clients, but this was simple, fast, and easy, IMHO, and it actually opened up more testing opportunities for me as its all code and automatable (is that a word).