'Tests for providing an alternate distance metric to the
generator.'

def test_metric(self):

    dist = l1dist
    G = nx.geographical_threshold_graph(50, 100, metric=dist)
    for (u, v) in combinations(G, 2):
        if (v in G[u]):
            assert_true(join(G, u, v, 100, 2, dist))
        else:
            assert_false(join(G, u, v, 100, 2, dist))
