General Test Create a site with at least two users on it that have no messages at all Log in as a user and navigate to the messaging page (user menu > messages) Make sure there are no errors in the developer console in the browser when the messaging area has no message Send a message to the other user Log in as the other user in a separate browser Send messages back and forth between each user, the messaging area should automatically update with the new messages between each user (there can be a small time delay for the update) Polling Back Off Test The polling is using a timeout that backs off over time if no messages are received from the check. As soon as a result is returned (or a new conversation selected) the timeout is reset back to the start (increased frequency). You can check the back off by viewing the network tab in the browser's developer tools and watch the requests for 'message_area_messages' become less and less frequent over time. Open your config.php file and edit the following $CFG->messagingminpoll, $CFG->messagingmaxpoll and $CFG->messagingtimeoutpoll ensure they are obeyed. messagingminpoll - The minimum time to poll. Eg. if this is set to '10' then it will poll a minimum of every 10 seconds (this will increment by 1 each time a message is not found). messagingmaxpoll - The maximum time to poll. Eg. if this is set to '120' then it will poll a maximum of 2 minutes until a message is received (then it will reset). messagingtimeoutpoll - The maximum timeout to poll. Eg. if this is set to '300' then once the 'messagingmaxpoll' has been reached it will then poll every 5 minutes until a message is received. Cache Test The timecreated value of the most recent message sent between each user is cached so that if we're requesting messages for sometime after that value we know there will be no results and we can avoid a DB call. To test this you can load the messaging page and give it a second or two to warm the cache and then a die() statement in the get_messages function after the cache check at around line 310 of message/classes/api.php. Then check your networks tab for your browser's developer tools and make sure the 'message_area_messages' requests are still returning correctly (because they should be returning because your die statement due to the cache).