This will be my final, definitive guess on this subject:
The subject of the photo is an Italian Bersagliere from the time period of the early twentieth century, up to around 1916 or 1917. From photographic evidence I've been able to find on the net and in my library, including a photo of a member of the Alpini wearing the same tunic, I'm guessing that the single-breasted tunic with hidden buttons and no pockets was of a type used in the early part of World War I by the Italian military. This would correspond to the hat, which was used before the widespread adoption of the French-style "Adrian" helmet in late 1916-early 1917. Most photographs (such as the one that
Walter posted) showing a tunic with breast pockets are from the later period of the war, which suggests that there was a redesign of uniforms (not uncommon - pretty much every army in WWI underwent a significant uniform redesign during the war).
Tunics from an earlier period, such as the American Civil War, would often have no breast pockets, but they wouldn't have hidden buttons. There's a good reason for that: there was no need to hide them. Camouflage for line troops (as opposed to specialty units, such as light infantry and snipers) was simply non-existent in the black-powder era. Hiding buttons only became an issue when armies were experimenting with ways to make their soldiers less conspicuous on the battlefield (other countries at that time would hide the buttons behind cloth coverings).
Et finalement, on trouve dans le
site du Musée royal de l’Armée (Belgique) le photo suivant:
Note the collar distinctions, the tunic, the hat, and the fingers on the mannequin. I rest my case.