Make PromiseConnection extend EventEmitter

The following events are re-emitted from the underlying Connection
instance:
 - error
 - drain
 - connect
 - end
 - enqueue

Author: Malte-Maurice Dreyer

promise.js

@@ -33,7 +33,10 @@ function createConnection (opts) {
 function PromiseConnection (connection, promiseImpl) {
   this.connection = connection;
   this.Promise = promiseImpl;
+
+  inheritEvents(connection, this, ['error', 'drain', 'connect', 'end', 'enqueue']);
 }
+util.inherits(PromiseConnection, EventEmitter);
 
 PromiseConnection.prototype.release = function () {
   this.connection.release();

test/integration/test-promise-wrappers.js

@@ -18,6 +18,7 @@ assert.equal(mainExport, createConnection);
 
 var doneCalled = false;
 var exceptionCaught = false;
+var doneEventsConnect = false;
 
 var doneCalledPool = false;
 var exceptionCaughtPool = false;
@@ -103,6 +104,38 @@ function testObjParams() {
     });
 }
 
+function testEventsConnect() {
+  var connPromise = createConnection(config).then(function(conn) {
+    var events = 0;
+
+    conn
+      .once('error', function(connection) {
+        ++events;
+      })
+      .once('drain', function(connection) {
+        ++events;
+      })
+      .once('connect', function() {
+        ++events;
+      })
+      .once('enqueue', function() {
+        ++events;
+      })
+      .once('end', function() {
+        ++events;
+
+        doneEventsConnect = events === 5;
+      });
+
+    conn.connection.emit('error');
+    conn.connection.emit('drain');
+    conn.connection.emit('connect');
+    conn.connection.emit('enqueue');
+    conn.connection.emit('end');
+    conn.end();
+  });
+}
+
 function testBasicPool() {
   var pool = createPool(config);
   pool
@@ -193,6 +226,7 @@ function testEventsPool() {
 testBasic();
 testErrors();
 testObjParams();
+testEventsConnect();
 testBasicPool();
 testErrorsPool();
 testObjParamsPool();
@@ -204,6 +238,7 @@ process.on('exit', function() {
   }
   assert.equal(doneCalled, true);
   assert.equal(exceptionCaught, true);
+  assert.equal(doneEventsConnect, true);
   assert.equal(doneCalledPool, true);
   assert.equal(exceptionCaughtPool, true);
   assert.equal(doneEventsPool, true);