'Tests that reversing the graph gives the "inward" Voronoi
partition.'

def test_directed_inward(self):

    G = nx.DiGraph(pairwise(range(6), cyclic=True))
    G.reverse(copy=False)
    cells = nx.voronoi_cells(G, {0, 3})
    expected = {0: {0, 4, 5}, 3: {1, 2, 3}}
    assert_equal(expected, cells)
