- Log in as an admin and go to the scheduled tasks page.
- Check that each scheduled task (apart from disabled ones) has a 'Run now' link.
- Click the 'Run now' link for a scheduled task.
- Check that the task is run, showing the same display as it would when it runs as part of normal cron.
- Try running a long-running scheduled task, such as 'Update all installed language packs' or 'Legacy cron processing for plugins'.
- Check that while the task runs, you see its output appear progressively (i.e. not all at once).
- Open a second browser so that you have two user sessions. Get both browsers in a position to run the same (long-running) scheduled task. Run the task very quickly from both browsers so that one is trying to start the task while the other is continuing it.
- Check that the task runs in the first browser and in the second you see the following debug information instead of the task output: "Unable to get task lock for [task class]."