def testKColor(self):
g = DalGraph(make_cycle(3))
c = g.k_color()
self.assertEqual(3, c, "KColor: K3 case")
g = DalGraph(make_cycle(4))
c = g.k_color()
self.assertEqual(None, c, "KColor: C4 case")
g = DalGraph(make_wheel(6))
c = g.k_color()
self.assertEqual(4, c, "KColor: W6 case")
c5 = make_cycle(5)
c5_2 = make_cycle(5)
c = join(c5,c5_2)
g = DalGraph(c)
c = g.k_color()
self.assertEqual(c, 6, "KColor: C5 joined with a C5")
