According to the usually reliable leakster @evleaks, the Samsung Galaxy S7 is already being tested in the US. Specifically, he said that two variants of the handset (SM-G930A and SM-G935A) - which should be the Galaxy S7 and Galaxy S7 edge - are under testing at AT&T.
AT&T already testing both Galaxy S7 variants (SM-G930A and -G935A), adding weight to rumors of an early- to mid-1Q16 release.— Evan Blass (@evleaks) November 13, 2015
The revelation adds weight to a recent rumor suggesting the flagship device(s) would be announced on February 21 2016 - just a day before next year's Mobile World Congress.
As for the specs, there's not much known at the moment, although there have been rumors that the device would sport a magnesium build, feature a USB Type-C port, and will come with 3D Touch-like features. A recent report also suggested that half of the Galaxy S7 units would be powered by the South Korean company's next generation Exynos 8890 chipset, while the other half would feature Snapdragon 820.