Engadget is reporting on “authority” that second-generation iPhone is already in testing and one of their trusted sources got a chance to check one out.

The second-generation iPhone will reportedly be “about the same size” as the current iPhone, feature 3G and “proper GPS.”

The appearance of the iPhone has reportedly changed from brushed metal rear to an entirely glossy black look with the volume buttons coming in chrome. The battery remains non-removable.

Finally the site reports that the second-generation iPhone will be only slightly thicker than the first, feature a headphone port that is flush with the body and feature the same size and resolution display.

The 3G iPhone is expected to ship in early July according to Engadget’s source.