Access testRunner objects from external jar files

Yes, you can use the api to call the external classes from groovy script. Only thing is that you need to pass the variables that are available in the groovy script such as log, context, testRunner to the user class, so that one would be able to access these variables in his classes. 

Implement your class(es), compile and build the jar file, then put it under SOAPUI_HOME/bin/ext and restart the SoapUI / Ready!API.

In your groovy script, just create the object of your class, like you do in java, then call the methods as you wish.

Here is an example class:

/**
* below is a groovy class example demonstrates
* how to access the soapui objects
* inside user class
**/
package demo.external.classes

SoapUIDemoClass {
  def context
  def log
  def testRunner

   def greet(def name) {
      log.info "Hello, ${name}"
   }

   def showTestCaseName() {
      log.info "Name of the test case is : ${testRunner.testCase.name}"
   }

   def getTestCasePropertyValue(def name) {
        context.testCase.properties[name].value
   }
}

Here is how you can call the above class methods in groovy script:

import demo.external.classes.SoapUIDemoClass

//Instaniating your class object with constructor
def demoClass = new SoapUIDemoClass(context: context, log: log, testRunner: testRunner)
//Call the method of user class
demoClass.greet("World!")
//Getting the test case property value using a method defined in user class
def value = demoClass.getTestCasePropertyValue('ANY_PROPERTY_THAT_YOU_HAVE')
log.info "Property value is : ${value}"
//logging the name of the test case from method of user defined class.
demoClass.showTestCaseName()