import com.google.common.collect.testing.SampleElements.Strings;
import java.util.List;
import java.util.Set;
import org.jspecify.annotations.NullMarked;

/**
 * Create string sets for collection tests.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@NullMarked
public abstract class TestStringSetGenerator implements TestSetGenerator<String> {
  @Override
  public SampleElements<String> samples() {
    return new Strings();
  }

import com.google.common.collect.testing.SampleElements.Strings;
import java.util.List;
import java.util.Set;
import org.jspecify.annotations.NullMarked;

/**
 * Create string sets for collection tests.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@NullMarked
public abstract class TestStringSetGenerator implements TestSetGenerator<String> {
  @Override
  public SampleElements<String> samples() {
    return new Strings();
  }

import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.jspecify.annotations.NullMarked;

/**
 * Unit test for {@link LinkedHashMultiset}.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@NullMarked
public class LinkedHashMultisetTest extends TestCase {

  @J2ktIncompatible
  @GwtIncompatible // suite
  @AndroidIncompatible // test-suite builders

 * java.util.function.Function}, making conversion code necessary only in one direction. At that
 * time, this interface will be officially discouraged.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@GwtCompatible
public interface Function<F extends @Nullable Object, T extends @Nullable Object> {
  /**

import java.lang.ref.WeakReference;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**
 * Unit test for {@link Interners}.
 *
 * @author Kevin Bourrillion
 */
@NullUnmarked
public class InternersTest extends TestCase {

  public void testStrong_simplistic() {
    String canonical = "a";
    String not = new String("a");

import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import org.jspecify.annotations.NullMarked;

/**
 * Implementation helper for {@link TestMapGenerator} for use with enum maps.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@NullMarked
public abstract class TestEnumMapGenerator implements TestMapGenerator<AnEnum, String> {

  @Override
  public SampleElements<Entry<AnEnum, String>> samples() {

import org.junit.Ignore;

/**
 * A generic JUnit test which tests addAll operations on a set. Can't be invoked directly; please
 * see {@link com.google.common.collect.testing.SetTestSuiteBuilder}.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.

import com.google.common.base.Preconditions;
import org.jspecify.annotations.Nullable;

/**
 * Implementation of {@link ImmutableSet} with exactly one element.
 *
 * @author Kevin Bourrillion
 * @author Nick Kralevich
 */
@GwtCompatible
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
final class SingletonImmutableSet<E> extends ImmutableSet<E> {

/**
 * A generic JUnit test which tests {@code listIterator} operations on a list. Can't be invoked
 * directly; please see {@link com.google.common.collect.testing.ListTestSuiteBuilder}.
 *
 * @author Chris Povirk
 * @author Kevin Bourrillion
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.

 * that conversion will be necessary in only one direction. At that time, this interface will be
 * officially discouraged.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@GwtCompatible
public interface Predicate<T extends @Nullable Object> {
  /**
   * Returns the result of applying this predicate to {@code input} (Java 8+ users, see notes in the