Throw a more helpful error if a client driver is created with an invalid URL.

lib/websocket/driver/client.js

@@ -20,6 +20,9 @@ var Client = function(_url, options) {
   var uri  = url.parse(this.url),
       auth = uri.auth && new Buffer(uri.auth, 'utf8').toString('base64');
 
+  if (this.VALID_PROTOCOLS.indexOf(uri.protocol) < 0)
+    throw new Error(this.url + ' is not a valid WebSocket URL');
+
   this._pathname = (uri.pathname || '/') + (uri.search || '');
 
   this._headers.set('Host', uri.host);
@@ -41,6 +44,8 @@ Client.generateKey = function() {
 };
 
 var instance = {
+  VALID_PROTOCOLS: ['ws:', 'wss:'],
+
   proxy: function(origin, options) {
     return new Proxy(this, origin, options);
   },

spec/websocket/driver/client_spec.js

@@ -109,6 +109,16 @@ test.describe("Client", function() { with(this) {
         }})
       }})
 
+      describe("with an invalid URL", function() { with(this) {
+        define("url", function() { return "stream.wikimedia.org/rc" })
+
+        it("throws an error", function() { with(this) {
+          var message
+          try { driver() } catch (e) { message = e.message }
+          assertEqual( "stream.wikimedia.org/rc is not a valid WebSocket URL", message )
+        }})
+      }})
+
       describe("with custom headers", function() { with(this) {
         before(function() { with(this) {
           driver().setHeader("User-Agent", "Chrome")