Assert a JSON array response is not empty

Here is an example code

import net.sf.json.groovy.JsonSlurper
def jsonArray = '''{
    "employees":[
		{"firstName":"John", "lastName":"Doe"},
		{"firstName":"Anna", "lastName":"Smith"},
		{"firstName":"Peter","lastName":"Jones"}
	]
}'''

def jsonSlurper = new JsonSlurper()
def object = jsonSlurper.parseText(jsonArray)
def employees = object.employees
log.info employees instanceof List
log.info employees.size()
if (employees){
	log.info "Employe array is not empty"
} else {
	log.info "Employee array is empty"
}

 An example with empty array

import net.sf.json.groovy.JsonSlurper
def jsonArray = '''{
    "employees":[]
}'''
def jsonSlurper = new JsonSlurper()
def object = jsonSlurper.parseText(jsonArray)
def employees = object.employees
if (!employees) {
	log.warn "Array is empty" 
}

 Hope this helps