
Set up the system provides.

  >>> from tests import *
  >>> from smart.backends.deb.base import FinkVirtualPkgs, DebRequires
  >>> localpath = "%s/aptdeb/fink-virtual-pkgs" % TESTDATADIR
  >>> pkgs = FinkVirtualPkgs(localpath)
  
Check for virtual package.

  >>> depends = DebRequires("macosx", None, None)
  >>> pkgs.matches(depends)
  True
  >>> depends = DebRequires("darwin", ">=" , "8-1")
  >>> pkgs.matches(depends)
  True

