assertEquals(0, ticker.read());
    assertSame(ticker, ticker.advance(10));
    assertEquals(10, ticker.read());
    ticker.advance(1, MILLISECONDS);
    assertEquals(1000010L, ticker.read());
    ticker.advance(Duration.ofMillis(1));
    assertEquals(2000010L, ticker.read());
  }

  public void testAutoIncrementStep_returnsSameInstance() {
    FakeTicker ticker = new FakeTicker();

            // Not using File#lastModified() to avoid a Linux JDK8 milliseconds precision bug: JDK-8177809.
            long artifactLastModified =
                    Files.getLastModifiedTime(packagedArtifactFile.toPath()).toMillis();

            if (session.getProjectBuildingRequest().getBuildStartTime() != null) {
                long buildStartTime =
                        session.getProjectBuildingRequest().getBuildStartTime().getTime();

#### A "professional" attack

Of course, the attackers would not try all this by hand, they would write a program to do it, possibly with thousands or millions of tests per second. And they would get just one extra correct letter at a time.

    assertTrue(Files.exists(temp));
    Files.setLastModifiedTime(temp, FileTime.fromMillis(0));
    assertEquals(0, Files.getLastModifiedTime(temp).toMillis());
    MoreFiles.touch(temp);
    assertThat(Files.getLastModifiedTime(temp).toMillis()).isNotEqualTo(0);
  }

  public void testCreateParentDirectories_root() throws IOException {

/**
 * A mutable object which accumulates double values and tracks some basic statistics over all the
 * values added so far. The values may be added singly or in groups. This class is not thread safe.
 *
 * @author Pete Gillin
 * @author Kevin Bourrillion
 * @since 20.0
 */
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault
public final class StatsAccumulator {

 * StatsAccumulator#add} and {@link StatsAccumulator#addAll} methods. For tests of the {@link
 * StatsAccumulator#snapshot} method which returns {@link Stats} instances, see {@link StatsTest}.
 *
 * @author Pete Gillin
 */
public class StatsAccumulatorTest extends TestCase {

  private StatsAccumulator emptyAccumulator;
  private StatsAccumulator emptyAccumulatorByAddAllEmptyIterable;

    // There are several well-known algorithms for rotating part of an array (or, equivalently,
    // exchanging two blocks of memory). This classic text by Gries and Mills mentions several:
    // https://ecommons.cornell.edu/bitstream/handle/1813/6292/81-452.pdf.
    // (1) "Reversal", the one we have here.

 * StatsAccumulator#add} and {@link StatsAccumulator#addAll} methods. For tests of the {@link
 * StatsAccumulator#snapshot} method which returns {@link Stats} instances, see {@link StatsTest}.
 *
 * @author Pete Gillin
 */
public class StatsAccumulatorTest extends TestCase {

  private StatsAccumulator emptyAccumulator;
  private StatsAccumulator emptyAccumulatorByAddAllEmptyIterable;

import java.util.DoubleSummaryStatistics;
import junit.framework.TestCase;

/**
 * Tests for {@link Stats}. This tests instances created by both {@link Stats#of} and {@link
 * StatsAccumulator#snapshot}.
 *
 * @author Pete Gillin
 */
public class StatsTest extends TestCase {

  public void testCount() {
    assertThat(EMPTY_STATS_VARARGS.count()).isEqualTo(0);
    assertThat(EMPTY_STATS_ITERABLE.count()).isEqualTo(0);

 * calculate <i>only</i> the mean.
 *
 * <p><b>Java 8+ users:</b> If you are not using any of the variance statistics, you may wish to use
 * built-in JDK libraries instead of this class.
 *
 * @author Pete Gillin
 * @author Kevin Bourrillion
 * @since 20.0
 */
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault
public final class Stats implements Serializable {

  private final long count;