key = new Object();
    cache.refresh(key);
    checkNothingLogged();
    stats = cache.stats();
    assertThat(stats.missCount()).isEqualTo(2);
    assertThat(stats.loadSuccessCount()).isEqualTo(3);
    assertThat(stats.loadExceptionCount()).isEqualTo(0);
    assertThat(stats.hitCount()).isEqualTo(0);

    assertThat(cache.get(key)).isSameInstanceAs(key);
    stats = cache.stats();

    key = new Object();
    cache.refresh(key);
    checkNothingLogged();
    stats = cache.stats();
    assertThat(stats.missCount()).isEqualTo(2);
    assertThat(stats.loadSuccessCount()).isEqualTo(3);
    assertThat(stats.loadExceptionCount()).isEqualTo(0);
    assertThat(stats.hitCount()).isEqualTo(0);

    assertThat(cache.get(key)).isSameInstanceAs(key);
    stats = cache.stats();

    assertThat(stats.min()).isEqualTo(MEGA_STREAM_MIN);
    assertThat(stats.max()).isEqualTo(MEGA_STREAM_MAX);
  }

  public void testOfPrimitiveLongStream() {
    Stats stats = Stats.of(megaPrimitiveDoubleStream().mapToLong(x -> (long) x));
    assertThat(stats.count()).isEqualTo(MEGA_STREAM_COUNT);
    assertThat(stats.mean()).isWithin(ALLOWED_ERROR * MEGA_STREAM_COUNT).of(MEGA_STREAM_MEAN);
    assertThat(stats.populationVariance())

  // Stats instances:

  static final Stats EMPTY_STATS_VARARGS = Stats.of();
  static final Stats EMPTY_STATS_ITERABLE = Stats.of(ImmutableList.<Double>of());
  static final Stats ONE_VALUE_STATS = Stats.of(ONE_VALUE);
  static final Stats OTHER_ONE_VALUE_STATS = Stats.of(OTHER_ONE_VALUE);
  static final Stats TWO_VALUES_STATS = Stats.of(TWO_VALUES);

    stats = cache.stats();
    assertThat(stats.requestCount()).isEqualTo(3);
    assertThat(stats.hitCount()).isEqualTo(1);
    assertThat(stats.hitRate()).isEqualTo(1.0 / 3);
    assertThat(stats.missCount()).isEqualTo(2);
    assertThat(stats.missRate()).isEqualTo(2.0 / 3);
    assertThat(stats.loadCount()).isEqualTo(2);
    assertThat(stats.totalLoadTime()).isAtLeast(totalLoadTime);
    totalLoadTime = stats.totalLoadTime();

    stats = cache.stats();
    assertThat(stats.requestCount()).isEqualTo(3);
    assertThat(stats.hitCount()).isEqualTo(1);
    assertThat(stats.hitRate()).isEqualTo(1.0 / 3);
    assertThat(stats.missCount()).isEqualTo(2);
    assertThat(stats.missRate()).isEqualTo(2.0 / 3);
    assertThat(stats.loadCount()).isEqualTo(2);
    assertThat(stats.totalLoadTime()).isAtLeast(totalLoadTime);
    totalLoadTime = stats.totalLoadTime();

  // Stats instances:

  static final Stats EMPTY_STATS_VARARGS = Stats.of();
  static final Stats EMPTY_STATS_ITERABLE = Stats.of(ImmutableList.<Double>of());
  static final Stats ONE_VALUE_STATS = Stats.of(ONE_VALUE);
  static final Stats OTHER_ONE_VALUE_STATS = Stats.of(OTHER_ONE_VALUE);
  static final Stats TWO_VALUES_STATS = Stats.of(TWO_VALUES);

/**
 * Tests for {@link StatsAccumulator}. This tests the stats methods for instances built with {@link
 * StatsAccumulator#add} and {@link StatsAccumulator#addAll}, and various error cases of the {@link
 * 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
 */

    assertThat(EMPTY_PAIRED_STATS.toString())
        .isEqualTo("PairedStats{xStats=Stats{count=0}, yStats=Stats{count=0}}");
    assertThat(MANY_VALUES_PAIRED_STATS.toString())
        .isEqualTo(
            "PairedStats{xStats="
                + MANY_VALUES_PAIRED_STATS.xStats()
                + ", yStats="
                + MANY_VALUES_PAIRED_STATS.yStats()
                + ", populationCovariance="

    assertThat(EMPTY_PAIRED_STATS.toString())
        .isEqualTo("PairedStats{xStats=Stats{count=0}, yStats=Stats{count=0}}");
    assertThat(MANY_VALUES_PAIRED_STATS.toString())
        .isEqualTo(
            "PairedStats{xStats="
                + MANY_VALUES_PAIRED_STATS.xStats()
                + ", yStats="
                + MANY_VALUES_PAIRED_STATS.yStats()
                + ", populationCovariance="