// source node and the second is the target node
    assertThat(network.edgesConnecting(N2, N1)).isEmpty();
  }

  @Test
  public void edgesConnecting_parallelEdges_undirected() {
    assume().that(network.allowsParallelEdges()).isTrue();
    assume().that(network.isDirected()).isFalse();

    addEdge(N1, N2, E12);
    addEdge(N1, N2, E12_A);
    addEdge(N2, N1, E21);