js: Add ServerError and ConnectionError types

docs/changelog.rst

@@ -85,6 +85,13 @@ Feature release.
   <https://github.com/cujojs/when/blob/master/docs/api.md#debugging-promises>`_.
   This version has been released to npm as Mopidy.js v0.3.0.
 
+- All of Mopidy.js' promise rejection values are now of the Error type. This
+  ensures that all JavaScript VMs will show a useful stack trace if a rejected
+  promise's value is used to throw an exception. To allow catch clauses to
+  handle different errors differently, server side errors are of the type
+  ``Mopidy.ServerError``, and connection related errors are of the type
+  ``Mopidy.ConnectionError``.
+
 **MPD frontend**
 
 - Proper command tokenization for MPD requests. This replaces the old regex

js/README.md

@@ -90,7 +90,9 @@ Changelog
 
 - All promise rejection values are now of the Error type. This ensures that all
   JavaScript VMs will show a useful stack trace if a rejected promise's value
-  is used to throw an exception.
+  is used to throw an exception. To allow catch clauses to handle different
+  errors differently, server side errors are of the type `Mopidy.ServerError`,
+  and connection related errors are of the type `Mopidy.ConnectionError`.
 
 ### 0.2.0 (2014-01-04)
 

js/src/mopidy.js

@@ -24,6 +24,20 @@ function Mopidy(settings) {
     }
 }
 
+Mopidy.ConnectionError = function (message) {
+    this.name = "ConnectionError";
+    this.message = message;
+};
+Mopidy.ConnectionError.prototype = new Error();
+Mopidy.ConnectionError.prototype.constructor = Mopidy.ConnectionError;
+
+Mopidy.ServerError = function (message) {
+    this.name = "ServerError";
+    this.message = message;
+};
+Mopidy.ServerError.prototype = new Error();
+Mopidy.ServerError.prototype.constructor = Mopidy.ServerError;
+
 Mopidy.WebSocket = websocket.Client;
 
 Mopidy.prototype._configure = function (settings) {
@@ -102,7 +116,7 @@ Mopidy.prototype._cleanup = function (closeEvent) {
     Object.keys(this._pendingRequests).forEach(function (requestId) {
         var resolver = this._pendingRequests[requestId];
         delete this._pendingRequests[requestId];
-        var error = new Error("WebSocket closed");
+        var error = new Mopidy.ConnectionError("WebSocket closed");
         error.closeEvent = closeEvent;
         resolver.reject(error);
     }.bind(this));
@@ -142,11 +156,14 @@ Mopidy.prototype._handleWebSocketError = function (error) {
 Mopidy.prototype._send = function (message) {
     switch (this._webSocket.readyState) {
     case Mopidy.WebSocket.CONNECTING:
-        return when.reject(new Error("WebSocket is still connecting"));
+        return when.reject(
+            new Mopidy.ConnectionError("WebSocket is still connecting"));
     case Mopidy.WebSocket.CLOSING:
-        return when.reject(new Error("WebSocket is closing"));
+        return when.reject(
+            new Mopidy.ConnectionError("WebSocket is closing"));
     case Mopidy.WebSocket.CLOSED:
-        return when.reject(new Error("WebSocket is closed"));
+        return when.reject(
+            new Mopidy.ConnectionError("WebSocket is closed"));
     default:
         var deferred = when.defer();
         message.jsonrpc = "2.0";
@@ -203,7 +220,7 @@ Mopidy.prototype._handleResponse = function (responseMessage) {
     if (responseMessage.hasOwnProperty("result")) {
         resolver.resolve(responseMessage.result);
     } else if (responseMessage.hasOwnProperty("error")) {
-        error = new Error(responseMessage.error.message);
+        error = new Mopidy.ServerError(responseMessage.error.message);
         error.code = responseMessage.error.code;
         error.data = responseMessage.error.data;
         resolver.reject(error);

js/test/mopidy-test.js

@@ -175,6 +175,7 @@ buster.testCase("Mopidy", {
                 }),
                 done(function (error) {
                     assert(error instanceof Error);
+                    assert(error instanceof Mopidy.ConnectionError);
                     assert.equals(error.message, "WebSocket closed");
                     assert.same(error.closeEvent, closeEvent);
                 })
@@ -398,6 +399,7 @@ buster.testCase("Mopidy", {
                 }),
                 done(function (error) {
                     assert(error instanceof Error);
+                    assert(error instanceof Mopidy.ConnectionError);
                     assert.equals(
                         error.message, "WebSocket is still connecting");
                 })
@@ -416,6 +418,7 @@ buster.testCase("Mopidy", {
                 }),
                 done(function (error) {
                     assert(error instanceof Error);
+                    assert(error instanceof Mopidy.ConnectionError);
                     assert.equals(error.message, "WebSocket is closing");
                 })
             );
@@ -433,6 +436,7 @@ buster.testCase("Mopidy", {
                 }),
                 done(function (error) {
                     assert(error instanceof Error);
+                    assert(error instanceof Mopidy.ConnectionError);
                     assert.equals(error.message, "WebSocket is closed");
                 })
             );
@@ -610,6 +614,7 @@ buster.testCase("Mopidy", {
                 }),
                 done(function (error) {
                     assert(error instanceof Error);
+                    assert(error instanceof Mopidy.ServerError);
                     assert.equals(error.code, responseError.code);
                     assert.equals(error.message, responseError.message);
                     refute.defined(error.data);