}

  @Test
  public void edges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.edges()).containsExactly(E11);
  }

  @Test
  public void incidentEdges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.incidentEdges(N1)).containsExactly(E11);

  }

  @Test
  public void edges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.edges()).containsExactly(E11);
  }

  @Test
  public void incidentEdges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.incidentEdges(N1)).containsExactly(E11);

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

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

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

  @Override

      ElementOrder<String> edgeOrder) {
    this.allowsSelfLoops = allowsSelfLoops;
    this.allowsParallelEdges = allowsParallelEdges;
    this.nodeOrder = nodeOrder;
    this.edgeOrder = edgeOrder;
  }

  @Override
  Network<Integer, String> createGraph() {
    networkBuilder =
        NetworkBuilder.directed()
            .allowsSelfLoops(allowsSelfLoops)
            .allowsParallelEdges(allowsParallelEdges)

    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);

  }

  @Test
  public void adjacentNodes_selfLoop() {
    assume().that(graph.allowsSelfLoops()).isTrue();

    putEdge(N1, N1);
    putEdge(N1, N2);
    assertThat(graph.adjacentNodes(N1)).containsExactly(N1, N2);
  }

  @Test
  public void predecessors_selfLoop() {
    assume().that(graph.allowsSelfLoops()).isTrue();

    putEdge(N1, N1);
    assertThat(graph.predecessors(N1)).containsExactly(N1);

   * UnsupportedOperationException}.
   *
   * <p>The default value is {@code false}.
   */
  @CanIgnoreReturnValue
  public ValueGraphBuilder<N, V> allowsSelfLoops(boolean allowsSelfLoops) {
    this.allowsSelfLoops = allowsSelfLoops;
    return this;
  }

  /**
   * Specifies the expected number of nodes in the graph.
   *

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

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

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

  @Override

  }

  @Test
  public void edges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.edges()).containsExactly(E11);
  }

  @Test
  public void incidentEdges_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.incidentEdges(N1)).containsExactly(E11);

   * UnsupportedOperationException}.
   *
   * <p>The default value is {@code false}.
   */
  @CanIgnoreReturnValue
  public GraphBuilder<N> allowsSelfLoops(boolean allowsSelfLoops) {
    this.allowsSelfLoops = allowsSelfLoops;
    return this;
  }

  /**
   * Specifies the expected number of nodes in the graph.
   *