Testing two Web Services for Equality

Question

There was a vb.net web service project that I think I successfully converted to c# web service. (all are asmx files - no WCF yet)

I want to compare these two web services for equality - to make sure that no inadvertent bugs have crept in.

What is the best way to compare two web services for equality?? I am thinking of writing a client that will send requests (for example - ajax ) to both the web methods, and compare the result.. but I am hopeful that there might be existing solutions that are being used for such purposes.. Please let me know what is the best way..

Answer 1

I assume that your service is not a trivial one; with that in mind, I don't think you can get a good answer from anyone without engaging into more details about the nature of the existing service.

My best bet though would be to use a combinatorial testing approach. I would start from the existing service schema and work my way up to a model that separates as much as possible negative from positive test cases - for better coverage. When it happened to me, I used this tool set to either annotate the service schema (from the WSDL) and automatically generate the test model, or to create a combinatorial test model from scratch. This is almost always neded with real life services, to make sure that the combinatorial engine generates good test cases. Regardless of the approach, all test cases are captured in an Excel file. I then use the tool to generate the request, execute the service call and capture both the request/response in another Excel file, for each test case. Running against the old version gives me the baseline's "expected" result set; comparing that with the results from the migrated version, eventually using selective criteria (eliminating GUIDs, timestamps, transaction ids, etc.), gives the verdict.