Wait until request executed successfully

HimanshuTayal 

Not sure why you want to run REST request from a groovy script instead of having a REST Request step. Any specific reason?

If the assertion is added REST Request, are not those executed directly instead of verifying them in Groovy Script?

Any ways, it appears that you do not need to wait or use sleep.

See if the below snippet of code helps (follow comments)

import static com.eviware.soapui.model.testsuite.TestStepResult.TestStepStatus.*
import com.eviware.soapui.impl.wsdl.teststeps.WsdlTestRequestStep
import com.eviware.soapui.impl.wsdl.teststeps.RestTestRequestStep
import com.eviware.soapui.impl.wsdl.teststeps.JdbcRequestTestStep
import com.eviware.soapui.impl.wsdl.teststeps.HttpTestRequestStep

/*
 Your code before run method comes here
*/
def result = step.run(testRunner, context)
def isStepRequestType = { model -> [WsdlTestRequestStep, RestTestRequestStep, JdbcRequestTestStep, HttpTestRequestStep].any { model.class == it} } 
switch(result.status) {
	case FAILED:
		log.error "${step.name} is executed, but failed"
		break
	case [OK, UNKNOWN] :
		log.info "${step.name} execution is finished successfully"
		if (isStepRequestType(step)) {
			def response = result.responseContent
			assert response, 'Response is null or empty'
	                log.debug response
			//Add other assertions on response as needed	- verification part
		}		
		break //last statement in case
	default:
		log.info result.status
		break
}