fix: event emit once more when 'response' is comming of socketio engine.

core/lib/engine_socketio.js

@@ -157,14 +157,13 @@ SocketIoEngine.prototype.step = function (requestSpec, ee) {
       data: template(requestSpec.emit.data, context)
     };
 
-    let endCallback = function (err, context) {
+    let endCallback = function (err, context, needEmit) {
       if (err) {
         debug(err);
       }
 
       if (isAcknowledgeRequired(requestSpec)) {
-        // Acknowledge required so add callback to emit
-        socketio.emit(outgoing.channel, outgoing.data, function () {
+        let ackCallback = function () {
           let response = {
             data: template(requestSpec.emit.acknowledge.data, context),
             capture: template(requestSpec.emit.acknowledge.capture, context),
@@ -183,10 +182,19 @@ SocketIoEngine.prototype.step = function (requestSpec, ee) {
             }
             return callback(err, context);
           });
-        });
+        }
+
+        // Acknowledge required so add callback to emit
+        if (needEmit) {
+          socketio.emit(outgoing.channel, outgoing.data, ackCallback);
+        } else {
+          ackCallback();
+        }
       } else {
         // No acknowledge data is expected, so emit without a listener
-        socketio.emit(outgoing.channel, outgoing.data);
+        if (needEmit) {
+          socketio.emit(outgoing.channel, outgoing.data);
+        }
         markEndTime(ee, context, startedAt);
         return callback(null, context);
       }
@@ -209,7 +217,7 @@ SocketIoEngine.prototype.step = function (requestSpec, ee) {
           }
           // Stop listening on the response channel
           socketio.off(response.channel);
-          return endCallback(err, context);
+          return endCallback(err, context, false);
         });
       });
       // Send the data on the specified socket.io channel
@@ -225,7 +233,7 @@ SocketIoEngine.prototype.step = function (requestSpec, ee) {
         }
       }, waitTime);
     } else {
-      endCallback(null, context);
+      endCallback(null, context, true);
     }
   };