public void testIdentityKeySetIteratorRemove() {
    BiMap<Integer, String> bimap =
        new AbstractBiMap<Integer, String>(
            new IdentityHashMap<Integer, String>(), new IdentityHashMap<String, Integer>()) {};
    bimap.put(1, "one");
    bimap.put(2, "two");
    bimap.put(3, "three");
    Iterator<Integer> iterator = bimap.keySet().iterator();
    iterator.next();
    iterator.next();

  public void testIdentityKeySetIteratorRemove() {
    BiMap<Integer, String> bimap =
        new AbstractBiMap<Integer, String>(
            new IdentityHashMap<Integer, String>(), new IdentityHashMap<String, Integer>()) {};
    bimap.put(1, "one");
    bimap.put(2, "two");
    bimap.put(3, "three");
    Iterator<Integer> iterator = bimap.keySet().iterator();
    iterator.next();
    iterator.next();

/**
 * A {@code BiMap} backed by an {@code EnumMap} instance for keys-to-values, and a {@code HashMap}
 * instance for values-to-keys. Null keys are not permitted, but null values are. An {@code
 * EnumHashBiMap} and its inverse are both serializable.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap">{@code BiMap}</a>.
 *
 * @author Mike Bostock

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.BiMap;
import com.google.common.collect.ImmutableBiMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import org.jspecify.annotations.NullMarked;

/**
 * Generators of various {@link com.google.common.collect.BiMap}s and derived collections.
 *
 * @author Jared Levy
 * @author Hayward Chan
 */

import com.google.common.collect.BiMap;
import com.google.common.collect.testing.AbstractMapTester;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map.Entry;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;
import org.junit.Ignore;

/** Skeleton for a tester of a {@code BiMap}. */
@GwtCompatible

  @J2ktIncompatible // Synchronized
  public void testSynchronizedBiMap() {
    BiMap<String, Integer> bimap = HashBiMap.create();
    bimap.put("one", 1);
    BiMap<String, Integer> sync = Maps.synchronizedBiMap(bimap);
    bimap.put("two", 2);
    sync.put("three", 3);
    assertEquals(ImmutableSet.of(1, 2, 3), bimap.inverse().keySet());
    assertEquals(ImmutableSet.of(1, 2, 3), sync.inverse().keySet());
  }

/**
 * Creates, based on your criteria, a JUnit test suite that exhaustively tests a {@code BiMap}
 * implementation.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible
public class BiMapTestSuiteBuilder<K, V>
    extends PerCollectionSizeTestSuiteBuilder<
        BiMapTestSuiteBuilder<K, V>, TestBiMapGenerator<K, V>, BiMap<K, V>, Entry<K, V>> {

                  @Override
                  protected BiMap<String, String> create(Entry<String, String>[] entries) {
                    BiMap<String, String> bimap = HashBiMap.create(entries.length);
                    for (Entry<String, String> entry : entries) {
                      checkArgument(!bimap.containsKey(entry.getKey()));
                      bimap.put(entry.getKey(), entry.getValue());
                    }

  @Override
  protected final void assertMoreInvariants(Map<K, V> map) {
    BiMap<K, V> bimap = (BiMap<K, V>) map;

    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
      assertEquals(entry.getKey(), bimap.inverse().get(entry.getValue()));
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());

   */
  public static <A, B> Converter<A, B> asConverter(BiMap<A, B> bimap) {
    return new BiMapConverter<>(bimap);
  }

  private static final class BiMapConverter<A, B> extends Converter<A, B> implements Serializable {
    private final BiMap<A, B> bimap;

    BiMapConverter(BiMap<A, B> bimap) {
      this.bimap = checkNotNull(bimap);
    }

    @Override
    protected B doForward(A a) {