}

  @Test
  public void addEdge_existingEdgeBetweenSameNodes() {
    assume().that(graphIsMutable()).isTrue();

    addEdge(N1, N2, E12);
    ImmutableSet<String> edges = ImmutableSet.copyOf(network.edges());
    assertThat(networkAsMutableNetwork.addEdge(N1, N2, E12)).isFalse();
    assertThat(network.edges()).containsExactlyElementsIn(edges);
  }

  @Test

    assertThrows(NullPointerException.class, () -> builder.put('a', 1, null));
  }

  private static <R, C, V> void validateTableCopies(Table<R, C, V> original) {
    Table<R, C, V> copy = ImmutableTable.copyOf(original);
    assertEquals(original, copy);
    validateViewOrdering(original, copy);

    Table<R, C, V> built = ImmutableTable.<R, C, V>builder().putAll(original).build();
    assertEquals(original, built);

              public Collection<String> create(String[] elements) {
                List<String> unfiltered = newArrayList();
                unfiltered.add("yyy");
                unfiltered.addAll(ImmutableList.copyOf(elements));
                unfiltered.add("zzz");
                return Collections2.filter(unfiltered, LENGTH_1);
              }
            })
        .named("Collections2.filter, no nulls")

  public void addEdge_existingEdgeBetweenSameNodes() {
    assume().that(graphIsMutable()).isTrue();

    assertThat(networkAsMutableNetwork.addEdge(N1, N2, E12)).isTrue();
    ImmutableSet<String> edges = ImmutableSet.copyOf(network.edges());
    assertThat(networkAsMutableNetwork.addEdge(N1, N2, E12)).isFalse();
    assertThat(network.edges()).containsExactlyElementsIn(edges);
    assertThat(networkAsMutableNetwork.addEdge(N2, N1, E12)).isFalse();

    for (int i = 0; i < 3; i++) {
      assertEquals(i + 1, list.get(i).intValue());
    }
    assertEquals(ImmutableList.of(1, 2, 3), ImmutableList.copyOf(list.iterator()));
    assertEquals(ImmutableList.of(1, 2, 3), ImmutableList.copyOf(list.toArray(new Integer[0])));
  }

  @J2ktIncompatible
  @GwtIncompatible // suite
  public static class BuiltTests extends TestCase {
    public static Test suite() {

  // TODO(cpovirk): should we reject null items, since the tests already check null automatically?
  @CanIgnoreReturnValue
  public RelationshipTester<T> addRelatedGroup(Iterable<? extends T> group) {
    groups.add(ImmutableList.copyOf(group));
    return this;
  }

  public void test() {
    for (int groupNumber = 0; groupNumber < groups.size(); groupNumber++) {
      ImmutableList<T> group = groups.get(groupNumber);

      return false;
    }

    // Since views are returned, we need to copy the edges that will be removed.
    // Thus we avoid modifying the underlying view while iterating over it.
    for (E edge : ImmutableList.copyOf(connections.incidentEdges())) {
      removeEdge(edge);
    }
    nodeConnections.remove(node);
    return true;
  }

  @Override
  @CanIgnoreReturnValue
  public boolean removeEdge(E edge) {

  MutableValueGraph<Integer, String> graph;

  @After
  public void validateGraphState() {
    assertStronglyEquivalent(graph, Graphs.copyOf(graph));
    assertStronglyEquivalent(graph, ImmutableValueGraph.copyOf(graph));

    Graph<Integer> asGraph = graph.asGraph();
    AbstractGraphTest.validateGraph(asGraph);
    assertThat(graph.nodes()).isEqualTo(asGraph.nodes());

                  @Override
                  protected Multiset<String> create(String[] elements) {
                    return new StandardImplForwardingMultiset<>(ImmutableMultiset.copyOf(elements));
                  }
                })
            .named("ForwardingMultiset[ImmutableMultiset] with standard " + "implementations")

      Optional<TestEnum> result = Enums.getIfPresent(shadowTestEnum, constant.name());
      assertThat(result).isPresent();
      shadowConstants.add(result.get());
    }
    assertEquals(ImmutableSet.<Object>copyOf(shadowTestEnum.getEnumConstants()), shadowConstants);
    Optional<TestEnum> result = Enums.getIfPresent(shadowTestEnum, "blibby");
    assertThat(result).isAbsent();
    return new WeakReference<>(shadowLoader);
  }