import java.util.Map;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A bimap (or "bidirectional map") is a map that preserves the uniqueness of its values as well as
 * that of its keys. This constraint enables bimaps to support an "inverse view", which is another
 * bimap containing the same entries as this bimap but with reversed keys and values.
 *
 * <h3>Implementations</h3>
 *
 * <ul>

  public void testCreate() {
    EnumBiMap<Currency, Country> bimap = EnumBiMap.create(Currency.class, Country.class);
    assertTrue(bimap.isEmpty());
    assertEquals("{}", bimap.toString());
    assertEquals(HashBiMap.create(), bimap);
    bimap.put(Currency.DOLLAR, Country.CANADA);
    assertEquals(Country.CANADA, bimap.get(Currency.DOLLAR));
    assertEquals(Currency.DOLLAR, bimap.inverse().get(Country.CANADA));
  }

@NullMarked
public abstract class AbstractBiMapTester<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMapTester<K, V> {

  @Override
  protected BiMap<K, V> getMap() {
    return (BiMap<K, V>) super.getMap();
  }

  static <K extends @Nullable Object, V extends @Nullable Object> Entry<V, K> reverseEntry(
      Entry<K, V> entry) {
    return mapEntry(entry.getValue(), entry.getKey());
  }

    getMap().forcePut(null, v1());

    expectContents(mapEntry((K) null, v1()));

    assertFalse(getMap().containsValue(v0()));

    assertTrue(getMap().containsValue(v1()));
    assertTrue(getMap().inverse().containsKey(v1()));
    assertNull(getMap().inverse().get(v1()));
    assertEquals(v1(), getMap().get(null));
    assertEquals(1, getMap().size());
  }

  public void testClearClearsInverse() {
    BiMap<V, K> inv = getMap().inverse();
    getMap().clear();
    assertTrue(getMap().isEmpty());
    assertTrue(inv.isEmpty());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testKeySetClearClearsInverse() {
    BiMap<V, K> inv = getMap().inverse();
    getMap().keySet().clear();
    assertTrue(getMap().isEmpty());
    assertTrue(inv.isEmpty());
  }

  public void testClearClearsInverse() {
    BiMap<V, K> inv = getMap().inverse();
    getMap().clear();
    assertTrue(getMap().isEmpty());
    assertTrue(inv.isEmpty());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testKeySetClearClearsInverse() {
    BiMap<V, K> inv = getMap().inverse();
    getMap().keySet().clear();
    assertTrue(getMap().isEmpty());
    assertTrue(inv.isEmpty());
  }

  public void testKeySetIteratorRemove() {
    int initialSize = getNumElements();
    Iterator<K> iterator = getMap().keySet().iterator();
    iterator.next();
    iterator.remove();
    assertEquals(initialSize - 1, getMap().size());
    assertEquals(initialSize - 1, getMap().inverse().size());
  }

@NullMarked
public abstract class AbstractBiMapTester<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMapTester<K, V> {

  @Override
  protected BiMap<K, V> getMap() {
    return (BiMap<K, V>) super.getMap();
  }

  static <K extends @Nullable Object, V extends @Nullable Object> Entry<V, K> reverseEntry(
      Entry<K, V> entry) {
    return mapEntry(entry.getValue(), entry.getKey());
  }

      ImmutableBiMap<K, V> bimap = (ImmutableBiMap<K, V>) map;
      // TODO(lowasser): if we need to make a copy of a BiMap because the
      // forward map is a view, don't make a copy of the non-view delegate map
      if (!bimap.isPartialView()) {
        return bimap;
      }
    }
    return copyOf(map.entrySet());
  }

  /**

import java.util.Collections;
import java.util.List;
import org.junit.Ignore;

/**
 * Tests for the {@code inverse} view of a BiMap.
 *
 * <p>This assumes that {@code bimap.inverse().inverse() == bimap}, which is not technically
 * required but is fulfilled by all current implementations.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")