assertThat(network.edgesConnecting("A", "B")).containsExactly("AB");
    assertThat(network.edgesConnecting("B", "A")).containsExactly("AB");
  }

  @Test
  public void immutableNetworkBuilder_appliesNetworkBuilderConfig() {
    ImmutableNetwork<String, Integer> emptyNetwork =
        NetworkBuilder.directed()
            .allowsSelfLoops(true)
            .nodeOrder(ElementOrder.<String>natural())