In your console, go to Connectors > Script Testing.
You should start with an example object (XML/JSON etc) to run your tests on.
This might be a request from a method you wish to call, or the response from said call.
Using the Script Testing Tool
Globaland paste in the object, ensuring you assign the correct datatype, and give it a useful name.
You can now continue to adjust your script until you’re happy with the output, pressing Run whenever you wish to update the output.
For more on scripting, see Connector Scripting