Facebook appears to be testing a feature that lets users set an expiration time on posts. After that time, the posts disappear, as photos and messages do in "ephemeral messaging" apps like Snapchat and Facebook`s own Slingshot.Users in New Zealand recently reported noticing the feature. For example, Jen Flitter of Auckland posted a screenshot on Sept. 8 showing expiration times ranging from one hour to seven days.Facebook confirmed to the technology website Mashable that it`s running a small pilot of the feature. In the Facebook help centre, it now lists the question, "How do I post something and set it to expire?" The answer given, last updated two weeks ago, is: "Setting posts to expire is only available in some regions right now."Facebook often tests features in New Zealand before releasing them more widely. BBC news reports that the feature is currently only available in New Zealand.Snapchat, which allows users to send photos – and more recently messages – that are automatically deleted a few seconds after being viewed, has been a popular competitor to Facebook since it launched in 2011.