* called more than once to add features in multiple groups.
   */
  @CanIgnoreReturnValue
  public B withFeatures(Feature<?>... features) {
    return withFeatures(asList(features));
  }

  @CanIgnoreReturnValue
  public B withFeatures(Iterable<? extends Feature<?>> features) {
    for (Feature<?> feature : features) {
      this.features.add(feature);
    }
    return self();

                  protected Set<String> create(String[] elements) {
                    return union(emptySet(), emptySet());
                  }
                })
            .named("empty U empty")
            .withFeatures(CollectionSize.ZERO, CollectionFeature.ALLOWS_NULL_VALUES)
            .createTestSuite());

    suite.addTest(
        SetTestSuiteBuilder.using(
                new TestStringSetGenerator() {

                    return table.rowKeySet();
                  }
                })
            .named("HashBasedTable.rowKeySet")
            .withFeatures(COLLECTION_FEATURES_REMOVE)
            .withFeatures(CollectionFeature.SUPPORTS_ITERATOR_REMOVE)
            .createTestSuite());

    suite.addTest(
        SortedSetTestSuiteBuilder.using(

              @Override
              public Set<String> create(String[] elements) {
                return emptySet();
              }
            })
        .named("emptySet")
        .withFeatures(CollectionFeature.SERIALIZABLE, CollectionSize.ZERO)
        .suppressing(suppressForEmptySet())
        .createTestSuite();
  }

  public Test testsForSingletonSet() {
    return SetTestSuiteBuilder.using(

                return Collections.checkedNavigableSet(innerSet, String.class);
              }
            })
        .named("checkedNavigableSet/TreeSet, natural")
        .withFeatures(
            SetFeature.GENERAL_PURPOSE,
            CollectionFeature.KNOWN_ORDER,
            CollectionFeature.SERIALIZABLE,
            CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,

                return Collections.checkedQueue(queue, String.class);
              }
            })
        .named("checkedQueue/LinkedList")
        .withFeatures(
            CollectionFeature.GENERAL_PURPOSE,
            CollectionFeature.ALLOWS_NULL_VALUES,
            CollectionFeature.KNOWN_ORDER,
            CollectionFeature.RESTRICTS_ELEMENTS,

                    putEntries(map, entries);
                    return Maps.unmodifiableNavigableMap(map);
                  }
                })
            .named("unmodifiableNavigableMap[SafeTreeMap]")
            .withFeatures(
                CollectionSize.ANY, MapFeature.ALLOWS_NULL_VALUES, CollectionFeature.SERIALIZABLE)
            .createTestSuite());
    suite.addTest(
        BiMapTestSuiteBuilder.using(

              @Override
              public List<String> create(String[] elements) {
                return emptyList();
              }
            })
        .named("emptyList")
        .withFeatures(CollectionFeature.SERIALIZABLE, CollectionSize.ZERO)
        .suppressing(suppressForEmptyList())
        .createTestSuite();
  }

  public Test testsForSingletonList() {
    return ListTestSuiteBuilder.using(

              @Override
              public List<String> create(String[] elements) {
                return emptyList();
              }
            })
        .named("emptyList")
        .withFeatures(CollectionFeature.SERIALIZABLE, CollectionSize.ZERO)
        .suppressing(suppressForEmptyList())
        .createTestSuite();
  }

  public Test testsForSingletonList() {
    return ListTestSuiteBuilder.using(

                    putEntries(map, entries);
                    return Maps.unmodifiableNavigableMap(map);
                  }
                })
            .named("unmodifiableNavigableMap[SafeTreeMap]")
            .withFeatures(
                CollectionSize.ANY, MapFeature.ALLOWS_NULL_VALUES, CollectionFeature.SERIALIZABLE)
            .createTestSuite());
    suite.addTest(
        BiMapTestSuiteBuilder.using(