Make sure error events are emitted by data source

lib/datasource.js

@@ -291,6 +291,7 @@ DataSource.prototype.setup = function (name, settings) {
       connector = result.connector;
       if (!connector) {
         console.error(result.error);
+        this.emit('error', new Error(result.error));
         return;
       }
     }
@@ -310,6 +311,7 @@ DataSource.prototype.setup = function (name, settings) {
       } else {
         // The connection fails, let's report it and hope it will be recovered in the next call
         console.error('Connection fails: ', err, '\nIt will be retried for the next request.');
+        this.emit('error', err);
         this.connecting = false;
       }
 
@@ -1878,6 +1880,19 @@ DataSource.prototype.ready = function (obj, args) {
   };
   this.once('connected', onConnected);
   this.once('error', onError);
+
+  // Set up a timeout to cancel the invocation
+  var timeout = this.settings.connectionTimeout || 5000;
+  setTimeout(function() {
+    self.removeListener('error', onError);
+    self.removeListener('connected', onConnected);
+    var params = [].slice.call(args);
+    var cb = params.pop();
+    if (typeof cb === 'function') {
+      cb(new Error('Timeout in connecting after ' + timeout + ' ms'));
+    }
+  }, timeout);
+
   if (!this.connecting) {
     this.connect();
   }

test/loopback-dl.test.js

@@ -245,6 +245,38 @@ describe('ModelBuilder define model', function () {
 
 });
 
+describe('DataSource ping', function() {
+  var ds = new DataSource('memory');
+  ds.settings.connectionTimeout = 50; // ms
+  ds.connector.connect = function(cb) {
+    // Mock up the long delay
+    setTimeout(cb, 100);
+  };
+  ds.connector.ping = function(cb) {
+    cb(new Error('bad connection 2'));
+  }
+
+  it('should report connection errors during ping', function(done) {
+    ds.ping(function(err) {
+      (!!err).should.be.true;
+      err.message.should.be.eql('bad connection 2');
+      done();
+    });
+  });
+
+  it('should cancel invocation after timeout', function(done) {
+    ds.connected = false; // Force connect
+    var Post = ds.define('Post', {
+      title: { type: String, length: 255 }
+    });
+    Post.create(function(err) {
+      (!!err).should.be.true;
+      err.message.should.be.eql('Timeout in connecting after 50 ms');
+      done();
+    });
+  });
+});
+
 describe('DataSource define model', function () {
   it('should be able to define plain models', function () {
     var ds = new DataSource('memory');