HashMultimap<String, Integer> multimap = HashMultimap.create();
    multimap.put("foo", 1);
    multimap.put("bar", 2);
    multimap.put("foo", 3);
    assertEquals(ImmutableSet.of(1, 3), multimap.get("foo"));
    assertEquals(2, multimap.expectedValuesPerKey);
  }

  public void testCreateFromMultimap() {
    HashMultimap<String, Integer> multimap = HashMultimap.create();
    multimap.put("foo", 1);
    multimap.put("bar", 2);

    assertContentsAnyOrder(multimap().get(k0()), v1(), v2());
    assertTrue(multimap().containsKey(k0()));
    assertFalse(multimap().containsEntry(k0(), v0()));
    assertTrue(multimap().containsEntry(k0(), v2()));
    assertEquals(oldSize + 1, multimap().size());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testReflectsMultimapRemove() {

    ImmutableMap<String, Integer> map = ImmutableMap.of("one", 1);
    ImmutableSetMultimap<String, Integer> multimap1 = map.asMultimap();
    ImmutableSetMultimap<String, Integer> multimap2 = map.asMultimap();
    assertEquals(1, multimap1.asMap().size());
    assertSame(multimap1, multimap2);
  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testNullPointers() {

      assertFalse(multimap().isEmpty());
    } else {
      assertNull(multimap().asMap().get(key));
    }

    assertEquals(values.size(), multimap().get(key).size());

    assertEquals(values.size() > 0, multimap().containsKey(key));
    assertEquals(values.size() > 0, multimap().keySet().contains(key));
    assertEquals(values.size() > 0, multimap().keys().contains(key));

    for (Collection<V> valueCollection : multimap().asMap().values()) {
      SortedSet<V> valueSet = (SortedSet<V>) valueCollection;
      assertEquals(multimap().valueComparator(), valueSet.comparator());
    }
  }

  public void testAsMapGetImplementsSortedSet() {
    for (K key : multimap().keySet()) {
      SortedSet<V> valueSet = (SortedSet<V>) multimap().asMap().get(key);

  public void testAsMapValuesImplementSet() {
    for (Collection<V> valueCollection : multimap().asMap().values()) {
      assertTrue(valueCollection instanceof Set);
    }
  }

  public void testAsMapGetImplementsSet() {
    for (K key : multimap().keySet()) {
      assertTrue(multimap().asMap().get(key) instanceof Set);
    }
  }

  @MapFeature.Require(SUPPORTS_REMOVE)

import com.google.common.collect.Multimap;

/**
 * Helper methods/assertions for use with {@code com.google.common.collect} types.
 *
 * @author Colin Decker
 */
@GwtCompatible
final class GoogleHelpers {

  private GoogleHelpers() {}

  static void assertEmpty(Multimap<?, ?> multimap) {
    if (!multimap.isEmpty()) {
      fail("Not true that " + multimap + " is empty");
    }
  }

    assertContentsAnyOrder(multimap().get(k0()), v1(), v2());
    assertTrue(multimap().containsKey(k0()));
    assertFalse(multimap().containsEntry(k0(), v0()));
    assertTrue(multimap().containsEntry(k0(), v2()));
    assertEquals(oldSize + 1, multimap().size());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testReflectsMultimapRemove() {

    assertEquals(HashMultiset.create(), multimap.keys());
    assertEquals(emptySet(), multimap.keySet());
    assertEquals(0, multimap.size());
    assertTrue(multimap.values().isEmpty());
    assertEquals("{}", multimap.toString());
  }

  public void testEmptyMultimapWrites() {
    Multimap<String, Integer> multimap = ImmutableListMultimap.of();

  }

  @MapFeature.Require({SUPPORTS_PUT, SUPPORTS_REMOVE})
  public void testReplaceValuesWithDuplicates() {
    int size = multimap().size();
    List<V> oldValues = new ArrayList<>(multimap().get(k0()));
    List<V> values = asList(v0(), v3(), v0());
    assertEquals(oldValues, new ArrayList<V>(multimap().replaceValues(k0(), values)));