extends AbstractContainerTester<Collection<E>, E> {

  // TODO: replace this with an accessor.
  protected Collection<E> collection;

  @Override
  protected Collection<E> actualContents() {
    return collection;
  }

  // TODO: dispose of this once collection is encapsulated.
  @Override
  @CanIgnoreReturnValue
  protected Collection<E> resetContainer(Collection<E> newContents) {

      return standardRemove(object);
    }

    @Override
    public boolean removeAll(Collection<?> collection) {
      return standardRemoveAll(collection);
    }

    @Override
    public boolean retainAll(Collection<?> collection) {
      return standardRetainAll(collection);
    }

    @Override
    public Object[] toArray() {
      return standardToArray();
    }

                  }

                  @Override
                  public SampleElements<Entry<String, Collection<String>>> samples() {
                    return new SampleElements<>(
                        Helpers.mapEntry("a", (Collection<String>) ImmutableSortedSet.of("alex")),
                        Helpers.mapEntry(

        "containsAll(sameElements) should return true",
        collection.containsAll(MinimalCollection.of(createSamplesArray())));
  }

  @SuppressWarnings("ModifyingCollectionWithItself")
  public void testContainsAll_self() {
    assertTrue("containsAll(this) should return true", collection.containsAll(collection));
  }

  public void testContainsAll_partialOverlap() {
    assertFalse(

            projectKeys.add(key);
        }
        return projectKeys;
    }

    private Collection<String> negate(Collection<String> scopes) {
        Collection<String> result = new HashSet<>();
        Collections.addAll(result, "system", "compile", "provided", "runtime", "test");

        for (String scope : scopes) {
            if ("compile".equals(scope)) {
                result.remove("compile");

      resetContainer();
      Collection<V> collection = multimap().get(key);
      multimap().clear();
      assertEmpty(collection);
    }
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testClearPropagatesToAsMapGet() {
    for (K key : sampleKeys()) {
      resetContainer();
      Collection<V> collection = multimap().asMap().get(key);

      resetContainer();
      Collection<V> collection = multimap().get(key);
      multimap().clear();
      assertEmpty(collection);
    }
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testClearPropagatesToAsMapGet() {
    for (K key : sampleKeys()) {
      resetContainer();
      Collection<V> collection = multimap().asMap().get(key);

        if (entry.getKey().equals(key)) {
          expectedValues.add(entry.getValue());
        }
      }

      Collection<V> collection = multimap().asMap().get(key);
      if (expectedValues.isEmpty()) {
        assertNull(collection);
      } else {
        assertEqualIgnoringOrder(expectedValues, collection);
      }
    }
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(ALLOWS_NULL_KEYS)

  private static final Collection<Integer> EMPTY_COLLECTION = Arrays.<Integer>asList();

  private static final Collection<Integer> SOME_COLLECTION = Arrays.asList(0, 1, 1);

  private static final Iterable<Integer> SOME_ITERABLE =
      new Iterable<Integer>() {
        @Override
        public Iterator<Integer> iterator() {
          return SOME_COLLECTION.iterator();
        }
      };

  private static final Feature<?>[] COLLECTION_FEATURES = {
    CollectionSize.ANY, CollectionFeature.ALLOWS_NULL_QUERIES
  };

  private static final Feature<?>[] COLLECTION_FEATURES_ORDER = {
    CollectionSize.ANY, CollectionFeature.KNOWN_ORDER, CollectionFeature.ALLOWS_NULL_QUERIES
  };

  private static final Feature<?>[] COLLECTION_FEATURES_REMOVE = {