def "normalizes to collection"() {
        expect:
        collectionize(null) == []
        collectionize(10) == [10]
        collectionize("a") == ["a"]

        List list = [2, 2, "three"] as List
        collectionize(list) == [2, 2, "three"]

        Object[] array = [1, 1, "three"]
        collectionize(array) == [1, 1, "three"]

        collectionize([list, array]) == [2, 2, "three", 1, 1, "three"]

    }

    @Override
    public Set<T> parseNotation(N notation) {
        Collection<N> notations = Cast.uncheckedNonnullCast(GUtil.collectionize(notation));
        if (notations.isEmpty()) {
            return Collections.emptySet();
        }
        if (notations.size() == 1) {

     *
     * @param input any object
     * @return collection of flattened input or single input wrapped in a collection.
     */
    @SuppressWarnings("MixedMutabilityReturnType")
    public static Collection<?> collectionize(Object input) {
        if (input == null) {
            return emptyList();
        } else if (input instanceof Collection) {
            Collection<?> out = new LinkedList<Object>();

     *
     * @param input any object
     * @return collection of flattened input or single input wrapped in a collection.
     */
    @SuppressWarnings("MixedMutabilityReturnType")
    public static Collection<?> collectionize(Object input) {
        if (input == null) {
            return emptyList();
        } else if (input instanceof Collection) {
            Collection<?> out = new LinkedList<Object>();

 * Note that this means a test should not require more than one CollectionSize, since a particular
 * collection instance can only be one size at once.
 *
 * @author George van den Driessche
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible
public enum CollectionSize implements Feature<Collection>, Comparable<CollectionSize> {
  /** Test an empty collection. */
  ZERO(0),

 * Note that this means a test should not require more than one CollectionSize, since a particular
 * collection instance can only be one size at once.
 *
 * @author George van den Driessche
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible
public enum CollectionSize implements Feature<Collection>, Comparable<CollectionSize> {
  /** Test an empty collection. */
  ZERO(0),

    // Split out all the specified sizes.
    Set<Feature<?>> sizesToTest = Helpers.<Feature<?>>copyToSet(CollectionSize.values());
    sizesToTest.retainAll(features);
    features.removeAll(sizesToTest);

    FeatureUtil.addImpliedFeatures(sizesToTest);
    sizesToTest.retainAll(
        Arrays.asList(CollectionSize.ZERO, CollectionSize.ONE, CollectionSize.SEVERAL));

    logger.fine("   Sizes: " + formatFeatureSet(sizesToTest));

    // Split out all the specified sizes.
    Set<Feature<?>> sizesToTest = Helpers.<Feature<?>>copyToSet(CollectionSize.values());
    sizesToTest.retainAll(features);
    features.removeAll(sizesToTest);

    FeatureUtil.addImpliedFeatures(sizesToTest);
    sizesToTest.retainAll(
        Arrays.asList(CollectionSize.ZERO, CollectionSize.ONE, CollectionSize.SEVERAL));

    logger.fine("   Sizes: " + formatFeatureSet(sizesToTest));

import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_REMOVE;
import static com.google.common.collect.testing.features.CollectionSize.ONE;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractCollectionTester;
import com.google.common.collect.testing.MinimalCollection;

import static com.google.common.collect.testing.features.CollectionSize.ONE;
import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.Helpers;
import com.google.common.collect.testing.features.CollectionSize;
import java.util.Collections;
import java.util.List;