'Test that nodes are added to predecessors and successors.
For more information, see GitHub issue #2370.'

def test_pred_succ(self):

    G = nx.DiGraph()
    G.add_edge(0, 1)
    H = G.edge_subgraph([(0, 1)])
    assert_equal(list(H.predecessors(0)), [])
    assert_equal(list(H.successors(0)), [1])
    assert_equal(list(H.predecessors(1)), [0])
    assert_equal(list(H.successors(1)), [])
