Map<? extends K, ? extends V> map, Comparator<? super K> comparator) {
    boolean sameComparator = false;
    if (map instanceof SortedMap) {
      SortedMap<?, ?> sortedMap = (SortedMap<?, ?>) map;
      Comparator<?> comparator2 = sortedMap.comparator();
      sameComparator =
          (comparator2 == null) ? comparator == NATURAL_ORDER : comparator.equals(comparator2);
    }

import com.google.common.annotations.GwtCompatible;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.SortedMap;

/**
 * Tests representing the contract of {@link SortedMap}. Concrete subclasses of this base class test
 * conformance of concrete {@link SortedMap} subclasses to that contract.
 *
 * @author Jared Levy
 */
// TODO: Use this class to test classes besides ImmutableSortedMap.

import com.google.common.base.Functions;
import java.util.SortedMap;

/**
 * Tests for {@link Maps#transformValues(SortedMap, Function)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class MapsSortedTransformValuesTest extends AbstractMapsTransformValuesTest {
  @Override
  protected SortedMap<String, String> makeEmptyMap() {

   * returns a {@link SortedMap}, instead of the {@link Map} specified in the {@link Table}
   * interface.
   *
   * @since 10.0 (<a href="https://github.com/google/guava/wiki/Compatibility" >mostly
   *     source-compatible</a> since 7.0)
   */
  @Override
  public SortedMap<C, V> row(R rowKey) {
    return new TreeRow(rowKey);
  }

  private class TreeRow extends Row implements SortedMap<C, V> {

    extends ForwardingMap<K, V> implements SortedMap<K, V> {
  // TODO(lowasser): identify places where thread safety is actually lost

  /** Constructor for use by subclasses. */
  protected ForwardingSortedMap() {}

  @Override
  protected abstract SortedMap<K, V> delegate();

  @Override
  @CheckForNull
  public Comparator<? super K> comparator() {

  @Override
  protected SortedMap<String, Integer> makeEmptyMap() {
    return new SimpleForwardingSortedMap<>(
        new TreeMap<String, Integer>(Ordering.<String>natural().nullsFirst()));
  }

  @Override
  protected SortedMap<String, Integer> makePopulatedMap() {
    final SortedMap<String, Integer> sortedMap = makeEmptyMap();
    sortedMap.put("one", 1);
    sortedMap.put("two", 2);
    sortedMap.put("three", 3);

  @Override
  public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
    return subMap(fromKey, true, toKey, false);
  }

  @Override
  public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
    return headMap(toKey, false);
  }

  @Override
  public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {

    }

    @Override
    public SortedMap<K, V> subMap(K fromKey, K toKey) {
      return delegate().subMap(fromKey, true, toKey, false);
    }

    @Override
    public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate().tailMap(fromKey, inclusive);
    }

    @Override
    public SortedMap<K, V> tailMap(K fromKey) {

    SortedMapDifferenceImpl(
        SortedMap<K, V> onlyOnLeft,
        SortedMap<K, V> onlyOnRight,
        SortedMap<K, V> onBoth,
        SortedMap<K, ValueDifference<V>> differences) {
      super(onlyOnLeft, onlyOnRight, onBoth, differences);
    }

    @Override
    public SortedMap<K, ValueDifference<V>> entriesDiffering() {
      return (SortedMap<K, ValueDifference<V>>) super.entriesDiffering();
    }

    SortedMapDifferenceImpl(
        SortedMap<K, V> onlyOnLeft,
        SortedMap<K, V> onlyOnRight,
        SortedMap<K, V> onBoth,
        SortedMap<K, ValueDifference<V>> differences) {
      super(onlyOnLeft, onlyOnRight, onBoth, differences);
    }

    @Override
    public SortedMap<K, ValueDifference<V>> entriesDiffering() {
      return (SortedMap<K, ValueDifference<V>>) super.entriesDiffering();
    }