What should I use for testing a web service?

[Fencer]

Hello, I need to write a test program for a web service. The web service 
publishes its method through a wsdl-file. I recall using SOAPpy in the 
past and as a I remember it, it was very easy to "load" the WSDL-file 
and call web service methods. But is SOAPpy really maintained anymore? 
Someone mentioned ZSI, but that too seems to be abadonware and my first 
impression was it's complicated to do what was so easy in SOAPpy (at 
least as I recall it).
So I guess my question is: what is a mature, actively-maintained 
SOAP/WSDL library that is easy to use for the scenario I have (which is 
testing an already existing service)?

- Fencer