}

  private static MutableGraph<Integer> createGraph(EdgeType edgeType) {
    switch (edgeType) {
      case UNDIRECTED:
        return GraphBuilder.undirected().allowsSelfLoops(true).build();
      case DIRECTED:
        return GraphBuilder.directed().allowsSelfLoops(true).build();
    }
    throw new IllegalStateException("Unexpected edge type: " + edgeType);
  }

  private static EdgeType oppositeType(EdgeType edgeType) {

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

    MutableGraph<Integer> expectedClosure = GraphBuilder.directed().allowsSelfLoops(true).build();
    expectedClosure.putEdge(N1, N1);
    expectedClosure.putEdge(N1, N2);

  @Parameters(name = "allowsSelfLoops={0}")
  public static Collection<Object[]> parameters() {
    return Arrays.asList(new Object[][] {{false}, {true}});
  }

  private final boolean allowsSelfLoops;
  private ImmutableGraph.Builder<Integer> graphBuilder;

  public StandardImmutableDirectedGraphTest(boolean allowsSelfLoops) {
    this.allowsSelfLoops = allowsSelfLoops;
  }

  @Override

  @Parameters(name = "allowsSelfLoops={0}")
  public static Collection<Object[]> parameters() {
    return Arrays.asList(new Object[][] {{false}, {true}});
  }

  private final boolean allowsSelfLoops;
  private ImmutableGraph.Builder<Integer> graphBuilder;

  public StandardImmutableUndirectedGraphTest(boolean allowsSelfLoops) {
    this.allowsSelfLoops = allowsSelfLoops;
  }

  @Override

          {true, ElementOrder.stable()},
        });
  }

  private final boolean allowsSelfLoops;
  private final ElementOrder<Integer> incidentEdgeOrder;

  public StandardMutableDirectedGraphTest(
      boolean allowsSelfLoops, ElementOrder<Integer> incidentEdgeOrder) {
    this.allowsSelfLoops = allowsSelfLoops;
    this.incidentEdgeOrder = incidentEdgeOrder;
  }

  @Override

          {true, ElementOrder.stable()},
        });
  }

  private final boolean allowsSelfLoops;
  private final ElementOrder<Integer> incidentEdgeOrder;

  public StandardMutableDirectedGraphTest(
      boolean allowsSelfLoops, ElementOrder<Integer> incidentEdgeOrder) {
    this.allowsSelfLoops = allowsSelfLoops;
    this.incidentEdgeOrder = incidentEdgeOrder;
  }

  @Override

  }

  /** Returns a string representation of this graph. */
  @Override
  public String toString() {
    return "isDirected: "
        + isDirected()
        + ", allowsSelfLoops: "
        + allowsSelfLoops()
        + ", nodes: "
        + nodes()
        + ", edges: "
        + edges();
  }

    this.allowsSelfLoops = allowsSelfLoops;
    this.allowsParallelEdges = allowsParallelEdges;
    this.nodeOrder = nodeOrder;
    this.edgeOrder = edgeOrder;
  }

  @Override
  MutableNetwork<Integer, String> createGraph() {
    return NetworkBuilder.directed()
        .allowsSelfLoops(allowsSelfLoops)
        .allowsParallelEdges(allowsParallelEdges)
        .nodeOrder(nodeOrder)
        .edgeOrder(edgeOrder)
        .build();

    this.allowsSelfLoops = allowsSelfLoops;
    this.allowsParallelEdges = allowsParallelEdges;
    this.nodeOrder = nodeOrder;
    this.edgeOrder = edgeOrder;
  }

  @Override
  MutableNetwork<Integer, String> createGraph() {
    return NetworkBuilder.undirected()
        .allowsSelfLoops(allowsSelfLoops)
        .allowsParallelEdges(allowsParallelEdges)
        .nodeOrder(nodeOrder)
        .edgeOrder(edgeOrder)
        .build();

    this.allowsSelfLoops = allowsSelfLoops;
    this.allowsParallelEdges = allowsParallelEdges;
    this.nodeOrder = nodeOrder;
    this.edgeOrder = edgeOrder;
  }

  @Override
  MutableNetwork<Integer, String> createGraph() {
    return NetworkBuilder.directed()
        .allowsSelfLoops(allowsSelfLoops)
        .allowsParallelEdges(allowsParallelEdges)
        .nodeOrder(nodeOrder)
        .edgeOrder(edgeOrder)
        .build();