private static final ImmutableNetwork<String, String> IMMUTABLE_NETWORK_B =
      NetworkBuilder.directed().<String, String>immutable().addNode("B").build();

  public PackageSanityTests() {
    MutableNetwork<String, String> mutableNetworkA = NetworkBuilder.directed().build();
    mutableNetworkA.addNode("a");
    MutableNetwork<String, String> mutableNetworkB = NetworkBuilder.directed().build();

   * that edge to {@code value} (overwriting the existing value, if any).
   *
   * <p>If the graph is directed, the resultant edge will be directed; otherwise, it will be
   * undirected.
   *
   * <p>If this graph is directed, {@code endpoints} must be ordered.
   *
   * <p>Values do not have to be unique. However, values must be non-null.
   *

  // Node order tests

  @Test
  public void nodeOrder_none() {
    MutableGraph<Integer> graph = GraphBuilder.directed().nodeOrder(unordered()).build();

    assertThat(graph.nodeOrder()).isEqualTo(unordered());
  }

  @Test
  public void nodeOrder_insertion() {
    MutableGraph<Integer> graph = GraphBuilder.directed().nodeOrder(insertion()).build();

    addNodes(graph);

    assertThat(graph.nodeOrder()).isEqualTo(insertion());

    successorIterator = graph.successors(node).iterator();
    return true;
  }

  /**
   * If the graph is directed, each ordered [source, target] pair will be visited once if there is
   * an edge connecting them.
   */
  private static final class Directed<N> extends EndpointPairIterator<N> {
    private Directed(BaseGraph<N> graph) {
      super(graph);
    }

    @Override
    @CheckForNull

      case DIRECTED:
        return GraphBuilder.directed().allowsSelfLoops(true).build();
      default:
        throw new IllegalStateException("Unexpected edge type: " + edgeType);
    }
  }

  private static EdgeType oppositeType(EdgeType edgeType) {
    switch (edgeType) {
      case UNDIRECTED:
        return EdgeType.DIRECTED;
      case DIRECTED:
        return EdgeType.UNDIRECTED;

    Graph<String> graph1 = ImmutableGraph.copyOf(GraphBuilder.directed().<String>build());
    Graph<String> graph2 = ImmutableGraph.copyOf(graph1);

    assertThat(graph2).isSameInstanceAs(graph1);
  }

  @Test
  public void immutableGraphBuilder_appliesGraphBuilderConfig() {
    ImmutableGraph<String> emptyGraph =
        GraphBuilder.directed()
            .allowsSelfLoops(true)

  /** Creates a new instance with the specified edge directionality. */
  private GraphBuilder(boolean directed) {
    super(directed);
  }

  /** Returns a {@link GraphBuilder} for building directed graphs. */
  public static GraphBuilder<Object> directed() {
    return new GraphBuilder<>(true);
  }

  /** Returns a {@link GraphBuilder} for building undirected graphs. */

  }

  @Test
  public void hasEdgeConnecting_directed_correct() {
    graph = ValueGraphBuilder.directed().build();
    graph.putEdgeValue(1, 2, "A");
    assertThat(graph.hasEdgeConnecting(EndpointPair.ordered(1, 2))).isTrue();
  }

  @Test
  public void hasEdgeConnecting_directed_backwards() {
    graph = ValueGraphBuilder.directed().build();
    graph.putEdgeValue(1, 2, "A");

  private static final ImmutableNetwork<String, String> IMMUTABLE_NETWORK_B =
      NetworkBuilder.directed().<String, String>immutable().addNode("B").build();

  public PackageSanityTests() {
    MutableNetwork<String, String> mutableNetworkA = NetworkBuilder.directed().build();
    mutableNetworkA.addNode("a");
    MutableNetwork<String, String> mutableNetworkB = NetworkBuilder.directed().build();

        ImmutableValueGraph.copyOf(ValueGraphBuilder.directed().<String, Integer>build());
    ValueGraph<String, Integer> graph2 = ImmutableValueGraph.copyOf(graph1);

    assertThat(graph2).isSameInstanceAs(graph1);
  }

  @Test
  public void incidentEdgeOrder_stable() {
    ImmutableValueGraph<String, Integer> immutableValueGraph =
        ImmutableValueGraph.copyOf(ValueGraphBuilder.directed().<String, Integer>build());