Graph<Integer> asGraph = graph.asGraph();
    AbstractGraphTest.validateGraph(asGraph);
    assertThat(graph.nodes()).isEqualTo(asGraph.nodes());
    assertThat(graph.edges()).isEqualTo(asGraph.edges());
    assertThat(graph.nodeOrder()).isEqualTo(asGraph.nodeOrder());
    assertThat(graph.incidentEdgeOrder()).isEqualTo(asGraph.incidentEdgeOrder());

    Graph<Integer> asGraph = graph.asGraph();
    AbstractGraphTest.validateGraph(asGraph);
    assertThat(graph.nodes()).isEqualTo(asGraph.nodes());
    assertThat(graph.edges()).isEqualTo(asGraph.edges());
    assertThat(graph.nodeOrder()).isEqualTo(asGraph.nodeOrder());
    assertThat(graph.incidentEdgeOrder()).isEqualTo(asGraph.incidentEdgeOrder());

      }

      @Override
      public Graph<N> asGraph() {
        if (AbstractBaseGraph.this instanceof Graph) {
          return (Graph<N>) AbstractBaseGraph.this;
        } else if (AbstractBaseGraph.this instanceof ValueGraph) {
          return ((ValueGraph<N, ?>) AbstractBaseGraph.this).asGraph();
        }
        throw new UnsupportedOperationException(

  }

  @Test
  public void edges_containsOrderMismatch() {
    addEdge(N1, N2, E12);
    assertThat(network.asGraph().edges()).doesNotContain(ENDPOINTS_N2N1);
    assertThat(network.asGraph().edges()).doesNotContain(ENDPOINTS_N1N2);
  }

  @Test
  public void edgesConnecting_orderMismatch() {
    addEdge(N1, N2, E12);
    IllegalArgumentException e =

    assertThat(asNetwork.edgeOrder()).isEqualTo(ElementOrder.unordered());
    assertThat(asNetwork.allowsParallelEdges()).isFalse();
    assertThat(asNetwork.asGraph()).isEqualTo(graph);

    Set<EndpointPair<N>> allEndpointPairs = new HashSet<>();

    for (N node : sanityCheckSet(graph.nodes())) {
      assertThat(nodeString).contains(node.toString());

    assertThat(transpose).isEqualTo(expectedTranspose);
    assertThat(transpose(transpose)).isSameInstanceAs(directedGraph);
    AbstractGraphTest.validateGraph(transpose.asGraph());

    assertThat(transpose.edgeValueOrDefault(N1, N2, null)).isNull();
    for (Integer node : directedGraph.nodes()) {
      assertThat(directedGraph.inDegree(node)).isSameInstanceAs(transpose.outDegree(node));

    assertThat(asNetwork.edgeOrder()).isEqualTo(ElementOrder.unordered());
    assertThat(asNetwork.allowsParallelEdges()).isFalse();
    assertThat(asNetwork.asGraph()).isEqualTo(graph);

    Set<EndpointPair<N>> allEndpointPairs = new HashSet<>();

    for (N node : sanityCheckSet(graph.nodes())) {
      assertThat(nodeString).contains(node.toString());

   * treated as if collapsed into a single edge. For example, the {@link #degree(Object)} of a node
   * in the {@link Graph} view may be less than the degree of the same node in this {@link Network}.
   */
  Graph<N> asGraph();

  //
  // Network properties
  //

  /**
   * Returns true if this network allows parallel edges. Attempting to add a parallel edge to a