You can go to "Function Test" tab from "Crossfire Admin".
Parameters are the inputs.
The return value is the output.
In the test, you enter the parameters you want to test and the expected result that the code will return.
Eg: The test I want to run is converting JSON to XML.
I added the JSON message as the input and the corresponding XML message to the expected result.
And then you run the test in Function Test.