    @Test
    public void testDirected()
    {

        final long seed = 5;

        GraphGenerator<Integer, DefaultEdge, Integer> gen =
            new KleinbergSmallWorldGraphGenerator<>(5, 2, 3, 2, seed);
        Graph<Integer, DefaultEdge> g = new SimpleDirectedGraph<>(DefaultEdge.class);
        gen.generateGraph(g, new IntegerVertexFactory(), null);

        assertEquals(25, g.vertexSet().size());
    }