}

  @Test
  public void hasEdgeConnecting_disconnectedNodes() {
    addNode(N1);
    addNode(N2);
    assertThat(network.hasEdgeConnecting(N1, N2)).isFalse();
  }

  @Test
  public void hasEdgesConnecting_nodesNotInGraph() {
    addNode(N1);
    addNode(N2);
    assertThat(network.hasEdgeConnecting(N1, NODE_NOT_IN_GRAPH)).isFalse();

  }

  @Test
  public void hasEdgeConnecting_disconnectedNodes() {
    addNode(N1);
    addNode(N2);
    assertThat(network.hasEdgeConnecting(N1, N2)).isFalse();
  }

  @Test
  public void hasEdgesConnecting_nodesNotInGraph() {
    addNode(N1);
    addNode(N2);
    assertThat(network.hasEdgeConnecting(N1, NODE_NOT_IN_GRAPH)).isFalse();

   * equivalent to {@code nodes().contains(nodeU) && successors(nodeU).contains(nodeV)}.
   *
   * <p>In an undirected graph, this is equal to {@code hasEdgeConnecting(nodeV, nodeU)}.
   *
   * @since 23.0
   */
  @Override
  boolean hasEdgeConnecting(N nodeU, N nodeV);

  /**
   * Returns true if there is an edge that directly connects {@code endpoints} (in the order, if

   * endpoints are unordered and the network is directed; it simply returns {@code false}. This is
   * for consistency with {@link Graph#hasEdgeConnecting(EndpointPair)} and {@link
   * ValueGraph#hasEdgeConnecting(EndpointPair)}.
   *
   * @since 27.1
   */
  boolean hasEdgeConnecting(EndpointPair<N> endpoints);

  //
  // Network identity
  //

  /**

   * equivalent to {@code nodes().contains(nodeU) && successors(nodeU).contains(nodeV)}.
   *
   * <p>In an undirected graph, this is equal to {@code hasEdgeConnecting(nodeV, nodeU)}.
   *
   * @since 23.0
   */
  @Override
  boolean hasEdgeConnecting(N nodeU, N nodeV);

  /**
   * Returns true if there is an edge that directly connects {@code endpoints} (in the order, if