added 'drain' event to client which fires after all pending queries

are done

lib/client.js

@@ -67,11 +67,16 @@ p.connect = function() {
   });
 };
 
+
 p.pulseQueryQueue = function() {
-  if(this.readyForQuery===true && this.queryQueue.length > 0) {
-    this.readyForQuery = false;
-    var query = this.queryQueue.shift();
-    query.submit(this.connection);
+  if(this.readyForQuery===true) {
+    if(this.queryQueue.length > 0) {
+      this.readyForQuery = false;
+      var query = this.queryQueue.shift();
+      query.submit(this.connection);
+    } else {
+      this.emit('drain');
+    }
   }
 };
 

test/unit/client/query-queue-tests.js

@@ -0,0 +1,49 @@
+var helper = require(__dirname + '/test-helper');
+var con = new Connection({stream: "NO"});
+var client = new Client({connection:con});
+
+
+con.connect = function() {
+  con.emit('connect');
+};
+con.query = function() {
+};
+client.connect();
+
+var raisedDrain = false;
+client.on('drain', function() {
+  raisedDrain = true;
+});
+
+client.query("hello");
+client.query("sup");
+client.query('boom');
+
+test("with pending queries", function() {
+  test("does not emit drain", function() {
+    assert.equal(raisedDrain, false);
+  });
+});
+
+test("after some queries executed", function() {
+  con.emit('readyForQuery');
+  test("does not emit drain", function() {
+    assert.equal(raisedDrain, false);
+  });
+});
+
+test("when all queries are sent", function() {
+  con.emit('readyForQuery');
+  con.emit('readyForQuery');
+  test("does not emit drain", function() {
+    assert.equal(raisedDrain, false);
+  });
+});
+
+test("after last query finishes", function() {
+  con.emit('readyForQuery');
+  test("emits drain", function() {
+    assert.ok(raisedDrain);
+  });
+});
+