import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.features.CollectionFeature;
import com.google.common.collect.testing.features.CollectionSize;
import java.util.NoSuchElementException;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code remove()} operations on a queue. Can't be invoked
 * directly; please see {@link com.google.common.collect.testing.CollectionTestSuiteBuilder}.

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)

    assertEquals(
        "next() should still return last element after peeking", "C", peekingIterator.next());

    assertThrows(NoSuchElementException.class, () -> peekingIterator.peek());
    assertThrows(NoSuchElementException.class, () -> peekingIterator.peek());
    assertThrows(NoSuchElementException.class, () -> peekingIterator.next());
  }

  public void testCantRemoveAfterPeek() {

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)

package com.google.common.collect;

import static com.google.common.collect.ReflectionFreeAssertThrows.assertThrows;

import com.google.common.annotations.GwtCompatible;
import java.util.Iterator;
import java.util.NoSuchElementException;
import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;

/**
 * Tests for {@link UnmodifiableIterator}.
 *
 * @author Jared Levy
 */
@GwtCompatible
@NullMarked

          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)
          .put(NullPointerException.class, e -> e instanceof NullPointerException)
          .put(NumberFormatException.class, e -> e instanceof NumberFormatException)

    Entry<K, V> entry = firstEntry();
    if (entry == null) {
      throw new NoSuchElementException();
    } else {
      return entry.getKey();
    }
  }

  @Override
  @ParametricNullness
  public K lastKey() {
    Entry<K, V> entry = lastEntry();
    if (entry == null) {
      throw new NoSuchElementException();
    } else {
      return entry.getKey();
    }
  }

  @Override