}

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

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

  }

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

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

  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 final EdgeType edgeType;
  private final MutableGraph<Integer> graph;

  // add parameters: directed/undirected
  @Parameters
  public static Collection<Object[]> parameters() {
    return Arrays.asList(new Object[][] {{EdgeType.UNDIRECTED}, {EdgeType.DIRECTED}});
  }

  public GraphEquivalenceTest(EdgeType edgeType) {
    this.edgeType = edgeType;
    this.graph = createGraph(edgeType);
  }

    MutableGraph<Integer> undirectedGraph =
        GraphBuilder.undirected().allowsSelfLoops(false).build();
    undirectedGraph.putEdge(N1, N2);
    undirectedGraph.putEdge(N1, N3);
    undirectedGraph.putEdge(N2, N3);
    undirectedGraph.addNode(N4);

    MutableGraph<Integer> expectedClosure = GraphBuilder.undirected().allowsSelfLoops(true).build();
    expectedClosure.putEdge(N1, N1);

  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. */
  public static GraphBuilder<Object> undirected() {
    return new GraphBuilder<>(false);
  }

  /**

  private final EdgeType edgeType;
  private final MutableNetwork<Integer, String> network;

  // add parameters: directed/undirected
  @Parameters
  public static Collection<Object[]> parameters() {
    return Arrays.asList(new Object[][] {{EdgeType.UNDIRECTED}, {EdgeType.DIRECTED}});
  }

  public NetworkEquivalenceTest(EdgeType edgeType) {
    this.edgeType = edgeType;
    this.network = createNetwork(edgeType);

  /**
   * Adds {@code edge} connecting {@code endpoints}. In an undirected network, {@code edge} will
   * also connect {@code nodeV} to {@code nodeU}.
   *
   * <p>If this graph is directed, {@code edge} will be directed in this graph; if it is undirected,
   * {@code edge} will be undirected in this graph.
   *
   * <p>If this graph is directed, {@code endpoints} must be ordered.
   *

    if (graph.isDirected()) {
      // Note: works for both directed and undirected graphs, but we only use in the directed case.
      for (N node : graph.nodes()) {
        for (N reachableNode : reachableNodes(graph, node)) {
          transitiveClosure.putEdge(node, reachableNode);
        }
      }
    } else {
      // An optimization for the undirected case: for every node B reachable from node A,

  Network<Integer, String> undirectedNetwork;

  @Before
  public void init() {
    MutableGraph<Integer> mutableDirectedGraph =
        GraphBuilder.directed().allowsSelfLoops(true).build();
    MutableGraph<Integer> mutableUndirectedGraph =
        GraphBuilder.undirected().allowsSelfLoops(true).build();
    graphsToTest = ImmutableList.of(mutableDirectedGraph, mutableUndirectedGraph);
    directedGraph = mutableDirectedGraph;