}

  public void testGetOnlyElement_withDefault_singleton() {
    Iterable<String> iterable = singletonList("foo");
    assertEquals("foo", getOnlyElement(iterable, "bar"));
  }

  public void testGetOnlyElement_withDefault_empty() {
    Iterable<String> iterable = emptyList();
    assertEquals("bar", getOnlyElement(iterable, "bar"));
  }

   * @throws IllegalArgumentException if the iterable contains multiple elements
   */
  @ParametricNullness
  public static <T extends @Nullable Object> T getOnlyElement(Iterable<T> iterable) {
    return Iterators.getOnlyElement(iterable.iterator());
  }

  /**
   * Returns the single element contained in {@code iterable}, or {@code defaultValue} if the
   * iterable is empty.
   *

    List<Future<String>> results;

    results = service.invokeAll(callables);
    assertThat(getOnlyElement(results)).isInstanceOf(TrustedListenableFutureTask.class);

    results = service.invokeAll(callables, 1, SECONDS);
    assertThat(getOnlyElement(results)).isInstanceOf(TrustedListenableFutureTask.class);

    /*
     * TODO(cpovirk): move ForwardingTestCase somewhere common, and use it to

 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.Iterables.getOnlyElement;
import static com.google.common.collect.Tables.immutableCell;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;

    List<Future<String>> results;

    results = service.invokeAll(callables);
    assertThat(getOnlyElement(results)).isInstanceOf(TrustedListenableFutureTask.class);

    results = service.invokeAll(callables, 1, SECONDS);
    assertThat(getOnlyElement(results)).isInstanceOf(TrustedListenableFutureTask.class);

    /*
     * TODO(cpovirk): move ForwardingTestCase somewhere common, and use it to

   * @throws IllegalArgumentException if the iterable contains multiple elements
   */
  @ParametricNullness
  public static <T extends @Nullable Object> T getOnlyElement(Iterable<T> iterable) {
    return Iterators.getOnlyElement(iterable.iterator());
  }

  /**
   * Returns the single element contained in {@code iterable}, or {@code defaultValue} if the
   * iterable is empty.
   *

      assertThat(future.isDone()).isTrue();
      // inspect state and ensure it is correct!
      // asserts that all get calling threads received the same value
      Object result = Iterables.getOnlyElement(finalResults);
      if (result == CancellationException.class) {
        assertTrue(future.isCancelled());
        if (future.wasInterrupted()) {

 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.Iterables.getOnlyElement;
import static com.google.common.collect.Tables.immutableCell;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;

    }
  }

  public void testWriteThroughEntry() {
    for (LoadingCache<Object, Object> cache : caches()) {
      cache.getUnchecked(1);
      Entry<Object, Object> entry = Iterables.getOnlyElement(cache.asMap().entrySet());

      cache.invalidate(1);
      assertThat(cache.size()).isEqualTo(0);

      entry.setValue(3);
      assertThat(cache.size()).isEqualTo(1);

      assertThat(future.isDone()).isTrue();
      // inspect state and ensure it is correct!
      // asserts that all get calling threads received the same value
      Object result = Iterables.getOnlyElement(finalResults);
      if (result == CancellationException.class) {
        assertTrue(future.isCancelled());
        if (future.wasInterrupted()) {