MutableNetwork<Integer, String> directedNetwork =
        NetworkBuilder.directed().allowsSelfLoops(true).build();
    directedNetwork.addNode(N0);
    directedNetwork.addEdge(N1, N2, E12);
    directedNetwork.addEdge(N2, N1, E21);
    directedNetwork.addEdge(N1, N3, E13);
    directedNetwork.addEdge(N4, N4, E44);
    containsExactlySanityCheck(
        directedNetwork.asGraph().edges(),

  private static final int NUM_NODES = 20;
  private static final int NUM_EDGES = 100;
  private static final int NODE_POOL_SIZE = 1000; // must be >> NUM_NODES

  @Test
  public void directedNetwork() {
    testNetworkMutation(NetworkBuilder.directed());
  }

  @Test
  public void undirectedNetwork() {
    testNetworkMutation(NetworkBuilder.undirected());
  }