putEdge(N1, N2);
    assertThat(graph.hasEdgeConnecting(EndpointPair.ordered(N1, N2))).isTrue();
  }

  @Test
  public void hasEdgeConnecting_backwards() {
    putEdge(N1, N2);
    assertThat(graph.hasEdgeConnecting(EndpointPair.ordered(N2, N1))).isFalse();
  }

  @Test
  public void hasEdgeConnecting_mismatch() {
    putEdge(N1, N2);
    assertThat(graph.hasEdgeConnecting(EndpointPair.unordered(N1, N2))).isFalse();

    return isDirected() ? successors(node).size() : degree(node);
  }

  @Override
  public boolean hasEdgeConnecting(N nodeU, N nodeV) {
    checkNotNull(nodeU);
    checkNotNull(nodeV);
    return nodes().contains(nodeU) && successors(nodeU).contains(nodeV);
  }

  @Override
  public boolean hasEdgeConnecting(EndpointPair<N> endpoints) {
    checkNotNull(endpoints);
    if (!isOrderingCompatible(endpoints)) {