}

  @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 =

  @Deprecated
  public static <N, E> ImmutableNetwork<N, E> copyOf(ImmutableNetwork<N, E> network) {
    return checkNotNull(network);
  }

  @Override
  public ImmutableGraph<N> asGraph() {
    return new ImmutableGraph<>(super.asGraph()); // safe because the view is effectively immutable
  }

  private static <N, E> Map<N, NetworkConnections<N, E>> getNodeConnections(Network<N, E> network) {

    assertThat(graph.nodes()).containsExactly(N1, N5, N4, N2, N3).inOrder();
    assertThat(graph.adjacentNodes(N1)).containsExactly(N4, N5);
    assertThat(graph.adjacentNodes(N2)).containsExactly(N3);
    assertThat(graph.adjacentNodes(N3)).containsExactly(N2);
    assertThat(graph.adjacentNodes(N4)).containsExactly(N1);
    assertThat(graph.adjacentNodes(N5)).containsExactly(N1);
  }

  @Test

  @SuppressWarnings("Immutable") // The backing graph must be immutable.
  private final BaseGraph<N> backingGraph;

  ImmutableGraph(BaseGraph<N> backingGraph) {
    this.backingGraph = backingGraph;
  }

  /** Returns an immutable copy of {@code graph}. */
  public static <N> ImmutableGraph<N> copyOf(Graph<N> graph) {
    return (graph instanceof ImmutableGraph)
        ? (ImmutableGraph<N>) graph
        : new ImmutableGraph<N>(

         *   v1<
         *      v3-v4
         *
         */
        graph = new MetadataGraph(4, 3);
        v1 = graph.addVertex(new ArtifactMetadata("g", "a1", "1.0"));
        graph.setEntry(v1);
        v2 = graph.addVertex(new ArtifactMetadata("g", "a2", "1.0"));
        v3 = graph.addVertex(new ArtifactMetadata("g", "a3", "1.0"));
        v4 = graph.addVertex(new ArtifactMetadata("g", "a4", "1.0"));

        // v1-->v2

      MutableGraph<Integer> graph = graphBuilder.allowsSelfLoops(true).build();

      assertThat(graph.nodes()).isEmpty();
      assertThat(graph.edges()).isEmpty();
      AbstractGraphTest.validateGraph(graph);

      while (graph.nodes().size() < NUM_NODES) {
        graph.addNode(gen.nextInt(NODE_POOL_SIZE));
      }
      ArrayList<Integer> nodeList = new ArrayList<>(graph.nodes());

  Iterator<N> successorIterator = ImmutableSet.<N>of().iterator();

  static <N> EndpointPairIterator<N> of(BaseGraph<N> graph) {
    return graph.isDirected() ? new Directed<N>(graph) : new Undirected<N>(graph);
  }

  private EndpointPairIterator(BaseGraph<N> graph) {
    this.graph = graph;
    this.nodeIterator = graph.nodes().iterator();
  }

  /**

    private static void addPhase(
            Graph graph, Graph.Vertex before, Graph.Vertex after, org.apache.maven.api.Lifecycle.Phase phase) {
        Graph.Vertex ep0 = graph.addVertex(BEFORE + phase.name());
        Graph.Vertex ep1 = graph.addVertex("$$" + phase.name());
        Graph.Vertex ep2 = graph.addVertex(phase.name());
        Graph.Vertex ep3 = graph.addVertex(AFTER + phase.name());
        graph.addEdge(ep0, ep1);

  mutable tensorflow::mutex mu;
  tensorflow::Graph graph TF_GUARDED_BY(mu);

  // Runs shape inference.
  tensorflow::ShapeRefiner refiner TF_GUARDED_BY(mu);

  // Maps from name of an operation to the Node* in 'graph'.
  std::unordered_map<std::string, tensorflow::Node*> name_map TF_GUARDED_BY(mu);

  // The keys of this map are all the active sessions using this graph. Each

  // In this case the graphs are considered equivalent; the property differences are irrelevant.
  @Test
  public void equivalent_propertiesDiffer() {
    graph.putEdge(N1, N2);

    MutableGraph<Integer> g2 =
        GraphBuilder.from(graph).allowsSelfLoops(!graph.allowsSelfLoops()).build();
    g2.putEdge(N1, N2);

    assertThat(graph).isEqualTo(g2);
  }