It seems that the original D&D 3.5 FAQ tackled this question in an official manner and while Pathfinder Second Ed it totally divorced of the 3.X legacy it is probably worth recognizing that it is assuredly in its bloodline still.

Old D&D 3.5 FAQ Archive from before the axed all 3.X support when 5th Ed released.

For brevity and ease so you don't have to download anything as I did...

Does darkvision allow a character to read and write in the dark? Can he see his reflection in a mirror?

Darkvision is described as the “ability to see with no light source at all” (DMG 292). This suggests that a character with darkvision can read, write, and otherwise perform a normal range of actions despite being in complete darkness. The simplest answer to the mirror question is yes. To avoid delving too deeply into real-world physics—something it’s best to resist, particularly in fantasy gaming—it’s easiest to treat darkvision as allowing a character to perceive anything that a normal person could see with light.