assertThat(network.edgeOrder()).isEqualTo(unordered());
    assertThat(network.nodeOrder()).isEqualTo(insertion()); // default
  }

  @Test
  public void edgeOrder_insertion() {
    MutableNetwork<Integer, String> network =
        NetworkBuilder.directed().edgeOrder(insertion()).build();

    addEdges(network);

    assertThat(network.edgeOrder()).isEqualTo(ElementOrder.insertion());

  }

  public void testMinMaxNatural() {
    assertThat(Comparators.min(1, 2)).isEqualTo(1);
    assertThat(Comparators.min(2, 1)).isEqualTo(1);
    assertThat(Comparators.max(1, 2)).isEqualTo(2);
    assertThat(Comparators.max(2, 1)).isEqualTo(2);
  }

  public void testMinMaxNatural_equalInstances() {
    Foo a = new Foo(1);
    Foo b = new Foo(1);

    assertThat(ordered.source()).isEqualTo("source");
    assertThat(ordered.target()).isEqualTo("target");
    assertThat(ordered.nodeU()).isEqualTo("source");
    assertThat(ordered.nodeV()).isEqualTo("target");
    assertThat(ordered.adjacentNode("source")).isEqualTo("target");
    assertThat(ordered.adjacentNode("target")).isEqualTo("source");
    assertThat(ordered.toString()).isEqualTo("<source -> target>");
  }

  @Test

    assertThat(ordered.source()).isEqualTo("source");
    assertThat(ordered.target()).isEqualTo("target");
    assertThat(ordered.nodeU()).isEqualTo("source");
    assertThat(ordered.nodeV()).isEqualTo("target");
    assertThat(ordered.adjacentNode("source")).isEqualTo("target");
    assertThat(ordered.adjacentNode("target")).isEqualTo("source");
    assertThat(ordered.toString()).isEqualTo("<source -> target>");
  }

  @Test

    assertThat(immutableValueGraph.asGraph()).isInstanceOf(ImmutableGraph.class);
    assertThat(immutableValueGraph).isNotInstanceOf(MutableValueGraph.class);
    assertThat(immutableValueGraph).isEqualTo(mutableValueGraph);

    mutableValueGraph.addNode("B");
    assertThat(immutableValueGraph).isNotEqualTo(mutableValueGraph);
  }

  @Test
  public void copyOfImmutableValueGraph_optimized() {

    comparator = Comparators.emptiesLast(naturalOrder());
  }

  public void testMinMaxNatural() {
    assertThat(Comparators.min(1, 2)).isEqualTo(1);
    assertThat(Comparators.min(2, 1)).isEqualTo(1);
    assertThat(Comparators.max(1, 2)).isEqualTo(2);
    assertThat(Comparators.max(2, 1)).isEqualTo(2);
  }

  public void testMinMaxNatural_equalInstances() {
    Foo a = new Foo(1);
    Foo b = new Foo(1);

    assertThat(immutableValueGraph.asGraph()).isInstanceOf(ImmutableGraph.class);
    assertThat(immutableValueGraph).isNotInstanceOf(MutableValueGraph.class);
    assertThat(immutableValueGraph).isEqualTo(mutableValueGraph);

    mutableValueGraph.addNode("B");
    assertThat(immutableValueGraph).isNotEqualTo(mutableValueGraph);
  }

  @Test
  public void copyOfImmutableValueGraph_optimized() {

      assertThat(mapCache.get(key)).isEqualTo(key + "_value");
    }
  }

  @Test
  public void testPutNewValue() {
    assertThat(mapCache.put("key", "value")).isNull();
    assertThat(mapCache.get("key")).isEqualTo("value"); // ensure key/value is cached
    assertThat(mapCache.put("key", "new value")).isEqualTo("value");
    assertThat(mapCache.get("key")).isEqualTo("new value");
  }

  @Test

    assertThat(emptyGraph.allowsSelfLoops()).isTrue();
    assertThat(emptyGraph.nodeOrder()).isEqualTo(ElementOrder.<String>natural());
  }

  @Test
  public void copyOf_incidentEdgeOrder() {
    ImmutableGraph<Object> graph = ImmutableGraph.copyOf(GraphBuilder.undirected().build());

    assertThat(graph.incidentEdgeOrder()).isEqualTo(ElementOrder.stable());
  }

  @Test

    ListenableFuture<String> f =
        new SimpleForwardingListenableFuture<String>(immediateFuture("a")) {};
    verify(!(f instanceof FluentFuture));
    assertThat(FluentFuture.from(f).get()).isEqualTo("a");
    // TODO(cpovirk): Test forwarding more extensively.
  }

  public void testAddCallback() {
    FluentFuture<String> f = FluentFuture.from(immediateFuture("a"));
    final boolean[] called = new boolean[1];