fail();
    } catch (NullPointerException expected) {
    }
  }

  public void testOnCharOverride() {
    Joiner onChar = Joiner.on('-');
    checkNoOutput(onChar, ITERABLE_);
    checkResult(onChar, ITERABLE_1, "1");
    checkResult(onChar, ITERABLE_12, "1-2");
    checkResult(onChar, ITERABLE_123, "1-2-3");
  }

  public void testSkipNulls() {
    Joiner skipNulls = J.skipNulls();

import java.lang.reflect.Modifier;
import java.util.List;
import junit.framework.TestCase;

/**
 * @param <S> the source or sink type
 * @param <T> the data type (byte[] or String)
 * @param <F> the factory type
 * @author Colin Decker
 */
@AndroidIncompatible // TODO(b/230620681): Make this available (even though we won't run it).
public class SourceSinkTester<S, T, F extends SourceSinkFactory<S, T>> extends TestCase {

import java.util.List;
import java.util.Map.Entry;
import java.util.SortedMap;

/**
 * Generators of sorted maps and derived collections.
 *
 * @author Kevin Bourrillion
 * @author Jesse Wilson
 * @author Jared Levy
 * @author Hayward Chan
 * @author Chris Povirk
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class SortedMapGenerators {

import java.util.List;
import java.util.Map.Entry;

/**
 * Implementation helper for {@link TestBiMapGenerator} for use with bimaps of strings.
 *
 * @author Chris Povirk
 * @author Jared Levy
 * @author George van den Driessche
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class TestStringBiMapGenerator implements TestBiMapGenerator<String, String> {

 * limitations under the License.
 */

package com.google.common.collect;

import java.util.HashMap;

/**
 * GWT emulation of {@link RegularImmutableBiMap}.
 *
 * @author Jared Levy
 * @author Hayward Chan
 */
@ElementTypesAreNonnullByDefault
@SuppressWarnings("serial")
class RegularImmutableBiMap<K, V> extends ImmutableBiMap<K, V> {
  static final RegularImmutableBiMap<Object, Object> EMPTY =

import java.util.Arrays;
import java.util.Map;
import java.util.Map.Entry;

/**
 * Generators of various {@link com.google.common.collect.BiMap}s and derived collections.
 *
 * @author Jared Levy
 * @author Hayward Chan
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class BiMapGenerators {
  public static class ImmutableBiMapGenerator extends TestStringBiMapGenerator {
    @Override

import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Implementation of {@link ImmutableSet} with exactly one element.
 *
 * @author Kevin Bourrillion
 * @author Nick Kralevich
 */
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
@ElementTypesAreNonnullByDefault

 *
 * <p>Time complexities for mutation methods are all O(1) except for {@code removeNode(N node)},
 * which is in O(d_node) where d_node is the degree of {@code node}.
 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 * @author Omar Darwish
 * @param <N> Node parameter type
 * @param <V> Value parameter type
 */
@ElementTypesAreNonnullByDefault

import java.util.Collection;
import java.util.Map;

/**
 * Test {@link Multimap#asMap()} for an arbitrary multimap with {@link MapInterfaceTest}.
 *
 * @author George van den Driessche
 * @author Jared Levy
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class AbstractMultimapAsMapImplementsMapTest
    extends MapInterfaceTest<String, Collection<Integer>> {

import java.io.Serializable;
import java.util.Map.Entry;
import javax.annotation.CheckForNull;

/**
 * {@code values()} implementation for {@link ImmutableMap}.
 *
 * @author Jesse Wilson
 * @author Kevin Bourrillion
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
final class ImmutableMapValues<K, V> extends ImmutableCollection<V> {
  private final ImmutableMap<K, V> map;