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

    assertThat(network.edgesConnecting(N1, N2)).containsExactly(E12, E12_A);
    // Passed nodes should be in the correct edge direction, first is the
    // source node and the second is the target node
    assertThat(network.edgesConnecting(N2, N1)).isEmpty();
  }

  @Test
  public void edgesConnecting_parallelEdges_undirected() {

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

    assertThat(network.edgesConnecting(N1, N2)).containsExactly(E12, E12_A);
    // Passed nodes should be in the correct edge direction, first is the
    // source node and the second is the target node
    assertThat(network.edgesConnecting(N2, N1)).isEmpty();
  }

  @Test
  public void edgesConnecting_parallelEdges_undirected() {