// this test is mainly checking that the contents of /dontdelete aren't deleted under
            // any circumstances
            assertEquals(3, MoreFiles.listFiles(symlinkTarget).size());

            Thread.yield();
          }
        } finally {
          executor.shutdownNow();
        }
      }
    }
  }

  public void testDeleteRecursively_nonDirectoryFile() throws IOException {

    assertThat(timer.elapsed(MILLISECONDS)).isAtLeast(10L);
    // wait for interrupted status and clear it
    while (!Thread.interrupted()) {
      Thread.yield();
    }
  }

  private static class Producer implements Callable<@Nullable Void> {
    final BlockingQueue<Object> q;
    final int elements;
    final CountDownLatch beganProducing = new CountDownLatch(1);

  private final Map<N, Object> adjacentNodeValues;

  /**
   * All node connections in this graph, in edge insertion order.
   *
   * <p>Note: This field and {@link #adjacentNodeValues} cannot be combined into a single
   * LinkedHashMap because one target node may be mapped to both a predecessor and a successor. A

 */
public abstract class AbstractGraphTest {

  Graph<Integer> graph;

  /**
   * The same reference as {@link #graph}, except as a mutable graph. This field is null in case
   * {@link #createGraph()} didn't return a mutable graph.
   */
  MutableGraph<Integer> graphAsMutableGraph;

  static final Integer N1 = 1;
  static final Integer N2 = 2;

   */
  public abstract static class NullsBefore implements Comparator<@Nullable String>, Serializable {
    /*
     * We don't serialize this class in GWT, so we don't care about whether GWT will serialize this
     * field.
     */
    @GwtTransient private final String justAfterNull;

    protected NullsBefore(String justAfterNull) {
      if (justAfterNull == null) {
        throw new NullPointerException();
      }

                }
              });
      expectedKeys.add(s);
    }

    computationLatch.countDown();
    // let some computations complete
    while (computedCount.get() < nThreads) {
      Thread.yield();
    }
    cache.invalidateAll();
    tasksFinished.await();

    // Check all of the removal notifications we received: they should have had correctly-associated

   * sake they are stored interleaved on alternate heap levels in the same array (MMPQ.queue).
   */
  @WeakOuter
  class Heap {
    final Ordering<E> ordering;

    @SuppressWarnings("nullness:initialization.field.uninitialized")
    @Weak
    Heap otherHeap; // always initialized immediately after construction

    Heap(Ordering<E> ordering) {
      this.ordering = ordering;
    }

 * that order.
 *
 * <p>By default, {@code Splitter}'s behavior is simplistic and unassuming. The following
 * expression:
 *
 * <pre>{@code
 * Splitter.on(',').split(" foo,,,  bar ,")
 * }</pre>
 *
 * ... yields the substrings {@code [" foo", "", "", " bar ", ""]}. If this is not the desired
 * behavior, use configuration methods to obtain a <i>new</i> splitter instance with modified
 * behavior:
 *
 * <pre>{@code

    equalsTester = new EqualsTester();
    equalObject1 = new ValidTestObject(1, 2);
    equalObject2 = new ValidTestObject(1, 2);
    notEqualObject1 = new ValidTestObject(0, 2);
  }

  /** Test null reference yields error */
  public void testAddNullReference() {
    try {
      equalsTester.addEqualityGroup((Object) null);
      fail("Should fail on null reference");
    } catch (NullPointerException e) {
    }
  }

   * identity equality of its Thread field so that the task field is only accessed by a single
   * thread.
   */
  private static final class ThreadConfinedTaskQueue {
    /**
     * This field is only used for identity comparisons with the current thread. Field assignments
     * are atomic, but do not provide happens-before ordering; however:
     *
     * <ul>