Use null-terminated string in the tests when sending a raw topic

Fix #771

Author: Minggang Wang

lib/node.js

@@ -602,7 +602,7 @@ class Node extends rclnodejs.ShadowNode {
    * @param {boolean} options.enableTypedArray - The topic will use TypedArray if necessary, default: true.
    * @param {QoS} options.qos - ROS Middleware "quality of service" settings for the subscription, default: QoS.profileDefault.
    * @param {boolean} options.isRaw - The topic is serialized when true, default: false.
-   * @param {SubscriptionCallback} callback - The callback to be call when receiving the topic subscribed.
+   * @param {SubscriptionCallback} callback - The callback to be call when receiving the topic subscribed. The topic will be an instance of null-terminated Buffer when options.isRaw is true.
    * @return {Subscription} - An instance of Subscription.
    * @see {@link SubscriptionCallback}
    */

test/test-raw-pub-sub.js

@@ -45,7 +45,10 @@ describe('rclnodejs publisher test suite', function () {
       { isRaw: true },
       (msg) => {
         clearInterval(timer);
-        assert.deepStrictEqual(Buffer.compare(msg, topic), 0);
+
+        // The received Buffer is null-terminated.
+        const buffer = Buffer.concat([topic, Buffer.from([0x00])]);
+        assert.deepStrictEqual(Buffer.compare(msg, buffer), 0);
         done();
       }
     );

types/node.d.ts

@@ -247,7 +247,7 @@ declare module 'rclnodejs' {
      * @param typeClass - Type of ROS messages the subscription will subscribe to
      * @param topic - Name of the topic the subcription will subscribe to.
      * @param options - Configuration options, see DEFAULT_OPTIONS
-     * @param callback - Called when a new message is received.
+     * @param callback - Called when a new message is received. The serialized message will be null-terminated.
      * @returns New instance of Subscription.
      */
     createSubscription<T extends TypeClass<MessageTypeClassName>>(