AbstractNetworkTest.validateNetwork(network);

      for (int i = numNodesToRemove; i < NUM_NODES; ++i) {
        assertThat(network.removeNode(nodeList.get(i))).isTrue();
      }

      assertThat(network.nodes()).isEmpty();
      assertThat(network.edges()).isEmpty(); // no edges can remain if there's no nodes
      AbstractNetworkTest.validateNetwork(network);

    Network<Integer, String> transpose = transpose(directedGraph);
    assertThat(transpose).isEqualTo(expectedTranspose);
    assertThat(transpose(transpose)).isSameInstanceAs(directedGraph);
    AbstractNetworkTest.validateNetwork(transpose);

    assertThat(transpose.edgesConnecting(N1, N2)).isEmpty();
    assertThat(transpose.edgeConnectingOrNull(N1, N2)).isNull();

    for (Integer node : directedGraph.nodes()) {

      networkAsMutableNetwork = (MutableNetwork<Integer, String>) network;
    }
  }

  @After
  public void validateNetworkState() {
    validateNetwork(network);
  }

  static <N, E> void validateNetwork(Network<N, E> network) {
    assertStronglyEquivalent(network, Graphs.copyOf(network));
    assertStronglyEquivalent(network, ImmutableNetwork.copyOf(network));