Currently, the testing site is always closed to the public, and is rarely open anymore. What happens at the testing site is usely map buildings, model buildings, and gear addons. Occasionally there will be leaks via Twitter. The leaks are small, or just a small section of a area in the map. Sometimes they may be big, or they may be incredibly small.
Current leak's Edit
All leaks can be found on Jolly's twitter page; www.twitter.com/jollycrazyboy66