public Set<E> outEdges(N node) {
    return delegate().outEdges(node);
  }

  @Override
  public EndpointPair<N> incidentNodes(E edge) {
    return delegate().incidentNodes(edge);
  }

  @Override
  public Set<E> adjacentEdges(E edge) {
    return delegate().adjacentEdges(edge);
  }

  @Override
  public int degree(N node) {
    return delegate().degree(node);
  }

  @Override

        SmbException ex = assertThrows(SmbException.class, () -> transport.hasCapability(42));
        assertTrue(ex.getMessage().contains("failed"));
        verify(transport).hasCapability(42);
    }

    // Edge: disconnected status toggles
    @ParameterizedTest
    @DisplayName("isDisconnected reflects current mocked state")
    @ValueSource(booleans = { true, false })
    void isDisconnected_states(boolean disconnected) {

  }

  @Override
  public int size() {
    return getConnectingEdge() == null ? 0 : 1;
  }

  @Override
  public boolean contains(@Nullable Object edge) {
    E connectingEdge = getConnectingEdge();
    return connectingEdge != null && connectingEdge.equals(edge);
  }

  private @Nullable E getConnectingEdge() {
    return nodeToOutEdge.get(targetNode);
  }

  ElementOrder<N> nodeOrder();

  //
  // Element-level accessors
  //

  /**
   * Returns a live view of the nodes which have an incident edge in common with {@code node} in
   * this graph.
   *
   * <p>This is equal to the union of {@link #predecessors(Object)} and {@link #successors(Object)}.
   *

    for (E edge : ImmutableList.copyOf(connections.incidentEdges())) {
      removeEdge(edge);
    }
    nodeConnections.remove(node);
    return true;
  }

  @Override
  @CanIgnoreReturnValue
  public boolean removeEdge(E edge) {
    checkNotNull(edge, "edge");

    N nodeU = edgeToReferenceNode.get(edge);
    if (nodeU == null) {
      return false;
    }

   *     #allowsParallelEdges()} or {@link #allowsSelfLoops()}
   */
  @CanIgnoreReturnValue
  boolean addEdge(N nodeU, N nodeV, E edge);

  /**
   * Adds {@code edge} connecting {@code endpoints}. In an undirected network, {@code edge} will
   * also connect {@code nodeV} to {@code nodeU}.
   *

  @Nullable N removeInEdge(E edge, boolean isSelfLoop);

  /** Remove {@code edge} from the set of outgoing edges. Returns the former successor node. */
  @CanIgnoreReturnValue
  N removeOutEdge(E edge);

  /**
   * Add {@code edge} to the set of incoming edges. Implicitly adds {@code node} as a predecessor.
   */
  void addInEdge(E edge, N node, boolean isSelfLoop);

  }

  @Override
  public N adjacentNode(E edge) {
    // Since the reference node is defined to be 'source' for directed graphs,
    // we can assume this edge lives in the set of outgoing edges.
    // (We're relying on callers to call this method only with an edge that's in the graph.)
    return requireNonNull(outEdgeMap.get(edge));
  }

  @Override
  public N removeInEdge(E edge, boolean isSelfLoop) {
    if (isSelfLoop) {

  }

  @Override
  public int size() {
    return getConnectingEdge() == null ? 0 : 1;
  }

  @Override
  public boolean contains(@Nullable Object edge) {
    E connectingEdge = getConnectingEdge();
    return connectingEdge != null && connectingEdge.equals(edge);
  }

  private @Nullable E getConnectingEdge() {
    return nodeToOutEdge.get(targetNode);
  }

  }

  // Node sets are the same, but edge sets differ.
  @Test
  public void equivalent_edgeSetsDiffer() {
    network.addEdge(N1, N2, E12);

    MutableNetwork<Integer, String> g2 = createNetwork(edgeType);
    g2.addEdge(N1, N2, E13);

    assertThat(network).isNotEqualTo(g2);
  }

  // Node/edge sets are the same, but node/edge connections differ due to edge type.
  @Test