public void testToString() {
    stopwatch.start();
    assertEquals("0.000 ns", stopwatch.toString());
    ticker.advance(1);
    assertEquals("1.000 ns", stopwatch.toString());
    ticker.advance(998);
    assertEquals("999.0 ns", stopwatch.toString());
    ticker.advance(1);
    assertEquals("1.000 \u03bcs", stopwatch.toString());
    ticker.advance(1);

   * the head of the list.
   */

  /** Returns the time that this entry was last accessed, in ns. */
  @SuppressWarnings("GoodTime")
  long getAccessTime();

  /** Sets the entry access time in ns. */
  @SuppressWarnings("GoodTime") // b/122668874
  void setAccessTime(long time);

  /** Returns the next entry in the access queue. */

   * the head of the list.
   */

  /** Returns the time that this entry was last accessed, in ns. */
  @SuppressWarnings("GoodTime")
  long getAccessTime();

  /** Sets the entry access time in ns. */
  @SuppressWarnings("GoodTime") // b/122668874
  void setAccessTime(long time);

  /** Returns the next entry in the access queue. */

  public void testToString() {
    stopwatch.start();
    assertEquals("0.000 ns", stopwatch.toString());
    ticker.advance(1);
    assertEquals("1.000 ns", stopwatch.toString());
    ticker.advance(998);
    assertEquals("999.0 ns", stopwatch.toString());
    ticker.advance(1);
    assertEquals("1.000 \u03bcs", stopwatch.toString());
    ticker.advance(1);

      return MICROSECONDS;
    }
    return NANOSECONDS;
  }

  private static String abbreviate(TimeUnit unit) {
    switch (unit) {
      case NANOSECONDS:
        return "ns";
      case MICROSECONDS:
        return "\u03bcs"; // μs
      case MILLISECONDS:
        return "ms";
      case SECONDS:
        return "s";
      case MINUTES:
        return "min";

      return MICROSECONDS;
    }
    return NANOSECONDS;
  }

  private static String abbreviate(TimeUnit unit) {
    switch (unit) {
      case NANOSECONDS:
        return "ns";
      case MICROSECONDS:
        return "\u03bcs"; // μs
      case MILLISECONDS:
        return "ms";
      case SECONDS:
        return "s";
      case MINUTES:
        return "min";