@CollectionSize.Require(absent = ZERO)
  public void testAddAll_unsupportedSomePresent() {
    assertThrows(
        UnsupportedOperationException.class,
        () -> collection.addAll(MinimalCollection.of(e3(), e0())));
    expectUnchanged();
  }

  @CollectionFeature.Require({SUPPORTS_ADD, FAILS_FAST_ON_CONCURRENT_MODIFICATION})
  @CollectionSize.Require(absent = ZERO)
  public void testAddAllConcurrentWithIteration() {

      a = entries.get(0);
      if (entries.size() >= 3) {
        c = entries.get(2);
      }
    }
  }

  @CollectionSize.Require(ZERO)
  public void testEmptyMapFirst() {
    assertThrows(NoSuchElementException.class, () -> navigableMap.firstKey());
  }

  @CollectionSize.Require(ZERO)
  public void testEmptyMapLast() {
    assertThrows(NoSuchElementException.class, () -> assertNull(navigableMap.lastKey()));
  }

        }
    }

    @Test
    @DisplayName("Zero-length message is handled correctly")
    void zeroLengthMessageHandled() throws IOException {
        // Create a zero-length message followed by a normal message
        byte[] data = new byte[] { 10, 20 };
        byte[] fullData = concat(messageHeader(0), // Zero-length message
                messageHeader(2), data);

  @CollectionSize.Require(absent = ZERO)
  public void testClearPropagatesToGet() {
    for (K key : sampleKeys()) {
      resetContainer();
      Collection<V> collection = multimap().get(key);
      multimap().clear();
      assertEmpty(collection);
    }
  }

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

  @CollectionSize.Require(absent = ZERO)
  public void testClearPropagatesToGet() {
    for (K key : sampleKeys()) {
      resetContainer();
      Collection<V> collection = multimap().get(key);
      multimap().clear();
      assertEmpty(collection);
    }
  }

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

   * @return the count of the element before the operation; possibly zero
   * @throws IllegalArgumentException if {@code count} is negative
   * @throws NullPointerException if {@code element} is null and this implementation does not permit
   *     null elements. Note that if {@code count} is zero, the implementor may optionally return
   *     zero instead.
   */
  @CanIgnoreReturnValue

 */

package com.google.common.collect.testing.testers;

import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_KEYS;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_KEY_QUERIES;

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class CollectionIsEmptyTester<E> extends AbstractCollectionTester<E> {
  @CollectionSize.Require(ZERO)
  public void testIsEmpty_yes() {
    assertTrue("isEmpty() should return true", collection.isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)
  public void testIsEmpty_no() {
    assertFalse("isEmpty() should return false", collection.isEmpty());
  }

  }

  @MapFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContains_nonNullWhenNullContained() {
    initMapWithNullValue();
    assertFalse("containsValue(notPresent) should return false", getMap().containsValue(v3()));
  }

  @MapFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContains_nullContained() {
    initMapWithNullValue();

  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContains_nonNullWhenNullContained() {
    initCollectionWithNullElement();
    assertFalse("contains(notPresent) should return false", collection.contains(e3()));
  }

  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContains_nullContained() {
    initCollectionWithNullElement();