We are trying to verify Service schema through "Ensure XML Validation" assertion but not able to achieve the desired results.
All supported DevTest releases.
Create a Web Service Test Case from the Quick Test Editor Panel.
The first step that it creates is the WSDL Validation step. This step by default will have the " Ensure XML Validation Assertion". DEVTEST will pick the default schema values. You don't need to do anything to add schema values.
Run the test in the ITR and see that the Assertion passed without any errors.
If you want to manually specify each schema to validate, you could try that too. Make sure you provide the right Namespace and Schema URL when you do that.
Refer to sections "WSDL Validation" , "Web Service Execution (XML) Step" and "Ensure XML Validation" in the documentation of the DevTest release you are running.