closes #6124

src/user/profile.js

@@ -196,7 +196,7 @@ module.exports = function (User) {
 
 	function updateUsername(uid, newUsername, callback) {
 		if (!newUsername) {
-			return callback();
+			return setImmediate(callback);
 		}
 
 		async.waterfall([
@@ -204,6 +204,9 @@ module.exports = function (User) {
 				User.getUserFields(uid, ['username', 'userslug'], next);
 			},
 			function (userData, next) {
+				if (userData.username === newUsername) {
+					return callback();
+				}
 				async.parallel([
 					function (next) {
 						updateUidMapping('username', uid, newUsername, userData.username, next);

test/user.js

@@ -627,6 +627,19 @@ describe('User', function () {
 			});
 		});
 
+		it('should not update a user\'s username if it did not change', function (done) {
+			socketUser.changeUsernameEmail({ uid: uid }, { uid: uid, username: 'updatedAgain', password: '123456' }, function (err) {
+				assert.ifError(err);
+				db.getSortedSetRevRange('user:' + uid + ':usernames', 0, -1, function (err, data) {
+					assert.ifError(err);
+					console.log(data);
+					assert(data[0].startsWith('updatedAgain'));
+					assert(data[1].startsWith('updatedUserName'));
+					done();
+				});
+			});
+		});
+
 		it('should change email', function (done) {
 			socketUser.changeUsernameEmail({ uid: uid }, { uid: uid, email: 'updatedAgain@me.com', password: '123456' }, function (err) {
 				assert.ifError(err);