doTestToArrayImpl2(Lists.<@Nullable Integer>newArrayList(1, null, 3), new Integer[2], false);
    doTestToArrayImpl2(Lists.<@Nullable Integer>newArrayList(1, null, 3), new Integer[3], true);
  }

  private void doTestToArrayImpl2(List<Integer> list, Integer[] array1, boolean expectModify) {
    Integer[] starting = Arrays.copyOf(array1, array1.length);

    Collection<List<Integer>> permutationSet =
        Collections2.permutations(Collections.<Integer>emptyList());

    assertEquals(1, permutationSet.size());
    assertTrue(permutationSet.contains(Collections.<Integer>emptyList()));

    Iterator<List<Integer>> permutations = permutationSet.iterator();
    assertNextPermutation(Collections.<Integer>emptyList(), permutations);

    Collection<List<Integer>> permutationSet =
        Collections2.permutations(Collections.<Integer>emptyList());

    assertEquals(1, permutationSet.size());
    assertTrue(permutationSet.contains(Collections.<Integer>emptyList()));

    Iterator<List<Integer>> permutations = permutationSet.iterator();
    assertNextPermutation(Collections.<Integer>emptyList(), permutations);

    MutableGraph<Integer> graph = GraphBuilder.directed().build();

    addNodes(graph);

    assertThat(graph.nodeOrder()).isEqualTo(insertion());
    assertThat(graph.nodes()).containsExactly(3, 1, 4).inOrder();
  }

  @Test
  public void nodeOrder_natural() {
    MutableGraph<Integer> graph =
        GraphBuilder.directed().nodeOrder(ElementOrder.<Integer>natural()).build();

    addNodes(graph);

    Function<Integer, Integer> adder =
        new Function<Integer, Integer>() {
          @Override
          public Integer apply(Integer from) {
            return from + holder.value;
          }
        };

    // Since holder.value is 2, applying 4 should yield 6.
    assertEquals(6, adder.apply(4).intValue());

    ListenableFuture<Integer> immediateFuture = immediateFuture(4);

/** Tests for {@link EndpointPair} and {@link Graph#edges()}. */
@RunWith(JUnit4.class)
public final class EndpointPairTest {
  private static final Integer N0 = 0;
  private static final Integer N1 = 1;
  private static final Integer N2 = 2;
  private static final Integer N3 = 3;
  private static final Integer N4 = 4;
  private static final String E12 = "1-2";
  private static final String E12_A = "1-2a";
  private static final String E21 = "2-1";

/** Tests for {@link EndpointPair} and {@link Graph#edges()}. */
@RunWith(JUnit4.class)
public final class EndpointPairTest {
  private static final Integer N0 = 0;
  private static final Integer N1 = 1;
  private static final Integer N2 = 2;
  private static final Integer N3 = 3;
  private static final Integer N4 = 4;
  private static final String E12 = "1-2";
  private static final String E12_A = "1-2a";
  private static final String E21 = "2-1";

  private static final Integer N1 = 1;
  private static final Integer N2 = 2;
  private static final Integer N3 = 3;

  private static final String E11 = "1-1";
  private static final String E12 = "1-2";
  private static final String E12_A = "1-2a";
  private static final String E13 = "1-3";

  private final EdgeType edgeType;
  private final MutableNetwork<Integer, String> network;

@RunWith(Parameterized.class)
public final class GraphEquivalenceTest {
  private static final Integer N1 = 1;
  private static final Integer N2 = 2;
  private static final Integer N3 = 3;

  private final EdgeType edgeType;
  private final MutableGraph<Integer> graph;

  // add parameters: directed/undirected
  @Parameters
  public static Collection<Object[]> parameters() {

  public void testTransformEquals() {
    Map<String, Integer> underlying = ImmutableMap.of("a", 0, "b", 1, "c", 2);
    Map<String, Integer> expected = Maps.transformValues(underlying, Functions.<Integer>identity());

    assertMapsEqual(expected, expected);

    Map<String, Integer> equalToUnderlying = Maps.newTreeMap();
    equalToUnderlying.putAll(underlying);
    Map<String, Integer> map =