// Node order tests

  @Test
  public void nodeOrder_none() {
    MutableGraph<Integer> graph = GraphBuilder.directed().nodeOrder(unordered()).build();

    assertThat(graph.nodeOrder()).isEqualTo(unordered());
  }

  @Test
  public void nodeOrder_insertion() {
    MutableGraph<Integer> graph = GraphBuilder.directed().nodeOrder(insertion()).build();

    addNodes(graph);

    assertThat(graph.nodeOrder()).isEqualTo(insertion());

    ImmutableNetwork<String, Integer> emptyNetwork =
        NetworkBuilder.directed()
            .allowsSelfLoops(true)
            .nodeOrder(ElementOrder.<String>natural())
            .<String, Integer>immutable()
            .build();

    assertThat(emptyNetwork.isDirected()).isTrue();
    assertThat(emptyNetwork.allowsSelfLoops()).isTrue();

  private static final int NODE_POOL_SIZE = 1000; // must be >> NUM_NODES

  @Test
  public void directedNetwork() {
    testNetworkMutation(NetworkBuilder.directed());
  }

  @Test
  public void undirectedNetwork() {
    testNetworkMutation(NetworkBuilder.undirected());
  }

  private static void testNetworkMutation(NetworkBuilder<? super Integer, Object> networkBuilder) {

  private static final int NODE_POOL_SIZE = 1000; // must be >> NUM_NODES

  @Test
  public void directedGraph() {
    testGraphMutation(GraphBuilder.directed());
  }

  @Test
  public void undirectedGraph() {
    testGraphMutation(GraphBuilder.undirected());
  }

  private static void testGraphMutation(GraphBuilder<? super Integer> graphBuilder) {

  private static final int NODE_POOL_SIZE = 1000; // must be >> NUM_NODES

  @Test
  public void directedGraph() {
    testGraphMutation(GraphBuilder.directed());
  }

  @Test
  public void undirectedGraph() {
    testGraphMutation(GraphBuilder.undirected());
  }

  private static void testGraphMutation(GraphBuilder<? super Integer> graphBuilder) {

    ImmutableNetwork<String, Integer> emptyNetwork =
        NetworkBuilder.directed()
            .allowsSelfLoops(true)
            .nodeOrder(ElementOrder.<String>natural())
            .<String, Integer>immutable()
            .build();

    assertThat(emptyNetwork.isDirected()).isTrue();
    assertThat(emptyNetwork.allowsSelfLoops()).isTrue();

  private static final int NODE_POOL_SIZE = 1000; // must be >> NUM_NODES

  @Test
  public void directedNetwork() {
    testNetworkMutation(NetworkBuilder.directed());
  }

  @Test
  public void undirectedNetwork() {
    testNetworkMutation(NetworkBuilder.undirected());
  }

  private static void testNetworkMutation(NetworkBuilder<? super Integer, Object> networkBuilder) {

    ImmutableValueGraph<String, Integer> emptyGraph =
        ValueGraphBuilder.directed()
            .allowsSelfLoops(true)
            .nodeOrder(ElementOrder.<String>natural())
            .<String, Integer>immutable()
            .build();

    assertThat(emptyGraph.isDirected()).isTrue();
    assertThat(emptyGraph.allowsSelfLoops()).isTrue();

    this.edgeCount = checkNonNegative(edgeCount);
  }

  @Override
  public Set<N> nodes() {
    return nodeConnections.unmodifiableKeySet();
  }

  @Override
  public boolean isDirected() {
    return isDirected;
  }

  @Override
  public boolean allowsSelfLoops() {
    return allowsSelfLoops;
  }

  @Override
  public ElementOrder<N> nodeOrder() {
    return nodeOrder;
  }

    ImmutableValueGraph<String, Integer> emptyGraph =
        ValueGraphBuilder.directed()
            .allowsSelfLoops(true)
            .nodeOrder(ElementOrder.<String>natural())
            .<String, Integer>immutable()
            .build();

    assertThat(emptyGraph.isDirected()).isTrue();
    assertThat(emptyGraph.allowsSelfLoops()).isTrue();