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);

    int edgeStart = graphString.indexOf("edges:");
    String nodeString = graphString.substring(nodeStart, edgeStart);

    Network<N, EndpointPair<N>> asNetwork = graph.asNetwork();
    // Don't call AbstractNetworkTest.validateNetwork(asNetwork).  Mutual recursion.
    assertThat(graph.nodes()).isEqualTo(asNetwork.nodes());
    assertThat(graph.edges()).hasSize(asNetwork.edges().size());
    assertThat(graph.nodeOrder()).isEqualTo(asNetwork.nodeOrder());

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

    assertThat(graph.allowsSelfLoops()).isEqualTo(asGraph.allowsSelfLoops());

    Network<Integer, EndpointPair<Integer>> asNetwork = graph.asNetwork();
    AbstractNetworkTest.validateNetwork(asNetwork);
    assertThat(graph.nodes()).isEqualTo(asNetwork.nodes());
    assertThat(graph.edges()).hasSize(asNetwork.edges().size());
    assertThat(graph.nodeOrder()).isEqualTo(asNetwork.nodeOrder());

    int edgeStart = graphString.indexOf("edges:");
    String nodeString = graphString.substring(nodeStart, edgeStart);

    Network<N, EndpointPair<N>> asNetwork = graph.asNetwork();
    // Don't call AbstractNetworkTest.validateNetwork(asNetwork).  Mutual recursion.
    assertThat(graph.nodes()).isEqualTo(asNetwork.nodes());
    assertThat(graph.edges()).hasSize(asNetwork.edges().size());
    assertThat(graph.nodeOrder()).isEqualTo(asNetwork.nodeOrder());

    assertThat(graph.allowsSelfLoops()).isEqualTo(asGraph.allowsSelfLoops());

    Network<Integer, EndpointPair<Integer>> asNetwork = graph.asNetwork();
    AbstractNetworkTest.validateNetwork(asNetwork);
    assertThat(graph.nodes()).isEqualTo(asNetwork.nodes());
    assertThat(graph.edges()).hasSize(asNetwork.edges().size());
    assertThat(graph.nodeOrder()).isEqualTo(asNetwork.nodeOrder());