Background: On Case Information/Custom fields, you can set case properties.  To debug a script, use case properties to determine values in variables, fields, or to see if an "if" statement evaluates to a section of code.
 
Method: Create the test case property and give it a name. Then, in the script, add a line like:
Event.Case.SetCaseProperty("Testing", "HDHP");

In this example, the code would write the value "HDHP" to the case property.  You could also put in a variable name, a field, or any value.