SoapUI
Rest OnRequest sample Groovy
http://www.soapui.org/apidocs/com/eviware/soapui/impl/rest/mock/RestMockRequest.html
http://www.soapui.org/apidocs/com/eviware/soapui/impl/rest/mock/RestMockResult.html
https://docs.oracle.com/javaee/6/api/javax/servlet/http/HttpServletResponse.html
https://docs.oracle.com/javaee/6/api/javax/servlet/http/HttpServletRequest.html
import com.eviware.soapui.impl.rest.mock.RestMockResult
RestMockResult res = new RestMockResult( mockRequest )
String val ="{test:1234}"
mockRequest.httpResponse.writer << val
mockRequest.httpResponse.status = 200
mockRequest.httpResponse.header = "Content-type: application/json"
mockRequest
return res