make sure it's not deadly nightshade!
http://t1.gstatic.com/images?q=tbn:ANd9GcSvUhC1dlnYNhicd3g2llWFC9kJDSr25sYiZJ_aX05LGVdTA4o&t=1&usg=__hMlZB5qerCsKcn72tDdFYWSEY4A=
http://t1.gstatic.com/images?q=tbn:ANd9GcRfhsTVi8Z3Dbd3mR758aLt21Fgs_kq8FkTR3vj-GamoviXHWw&t=1&usg=__4NZ5XJHEfjahuYGvDDvKj9XfAc0=
http://t3.gstatic.com/images?q=tbn:ANd9GcSHMKoudfhcOJfPbo3FJwZZekaBLejpfhKXvgIsi18xcPoEV0o&t=1&usg=__dLpUvHcm2FGqrVJqCS12vtjY0Ks=
nightshades can have various shaped leaves, so don't rely on that alone to ID the plant as a nightshade or not. Let it ripen if you can. Anything dark purple or black, do not eat and even if it's red, be very careful.
You could also take a branch to a local extension service or master gardener, they could help you ID it. Probably safer to do that than rely on us on the internet who can't really see all the details.