Reject current CDP commands after connection closed

Close #489

Author: aleksandrebd

lib/chrome.js

@@ -111,6 +111,7 @@ class Chrome extends EventEmitter {
                 this._ws.removeAllListeners('close');
                 this._ws.once('close', () => {
                     this._ws.removeAllListeners();
+                    this._handleConnectionClose();
                     callback();
                 });
                 this._ws.close();
@@ -239,6 +240,7 @@ class Chrome extends EventEmitter {
                 this._handleMessage(message);
             });
             this._ws.on('close', (code) => {
+                this._handleConnectionClose();
                 this.emit('disconnect');
             });
             this._ws.on('error', (err) => {
@@ -247,6 +249,15 @@ class Chrome extends EventEmitter {
         });
     }
 
+    _handleConnectionClose() {
+        // make sure to complete all the unresolved callbacks
+        const err = new Error('WebSocket connection closed');
+        for (const callback of Object.values(this._callbacks)) {
+            callback(true, err);
+        }
+        this._callbacks = {};
+    }
+
     // handle the messages read from the WebSocket
     _handleMessage(message) {
         // command response

test/send.js

@@ -79,6 +79,19 @@ describe('sending a command', () => {
             });
         });
     });
+    it('should catch WebSocket errors after command send', (done) => {
+        Chrome((chrome) => {
+            let result;
+            chrome.Page.enable((err, res)=>{
+                result = res;
+            });
+            chrome.close(()=>{
+                assert(result instanceof Error);
+                assert(result.message === 'WebSocket connection closed');
+                done();
+            });
+        });
+    });
     describe('without a callback', () => {
         it('should fulfill the promise if the command succeeds', (done) => {
             Chrome((chrome) => {