public void testSampleCovariance() {
    assertThrows(IllegalStateException.class, () -> emptyAccumulator.sampleCovariance());
    assertThrows(
        IllegalStateException.class,
        () -> emptyAccumulatorByAddAllEmptyPairedStats.sampleCovariance());
    assertThrows(IllegalStateException.class, () -> oneValueAccumulator.sampleCovariance());
    assertThrows(
        IllegalStateException.class,

    Iterator<String> iterator = iterable.iterator();
    assertFalse(iterator.hasNext());
    assertThrows(NoSuchElementException.class, () -> iterator.next());
    assertThrows(IllegalStateException.class, () -> iterable.iterator());
  }

  public void testOf_one() {
    Iterable<String> iterable = MinimalIterable.of("a");
    Iterator<String> iterator = iterable.iterator();
    assertTrue(iterator.hasNext());

  }

  public void testSampleVariance() {
    assertThrows(IllegalStateException.class, () -> EMPTY_STATS_VARARGS.sampleVariance());
    assertThrows(IllegalStateException.class, () -> EMPTY_STATS_ITERABLE.sampleVariance());
    assertThrows(IllegalStateException.class, () -> ONE_VALUE_STATS.sampleVariance());
    assertThat(TWO_VALUES_STATS.sampleVariance())
        .isWithin(ALLOWED_ERROR)

    assertThrows(IllegalStateException.class, () -> builder.maximumWeight(16));
    assertThrows(IllegalStateException.class, () -> builder.maximumSize(16));
  }

  @GwtIncompatible // maximumWeight
  public void testMaximumWeight_withoutWeigher() {
    CacheBuilder<Object, Object> builder = CacheBuilder.newBuilder().maximumWeight(1);
    assertThrows(IllegalStateException.class, () -> builder.build(identityLoader()));

  public void testSampleVariance() {
    assertThrows(IllegalStateException.class, () -> emptyAccumulator.sampleVariance());
    assertThrows(
        IllegalStateException.class, () -> emptyAccumulatorByAddAllEmptyIterable.sampleVariance());
    assertThrows(
        IllegalStateException.class, () -> emptyAccumulatorByAddAllEmptyStats.sampleVariance());
    assertThrows(IllegalStateException.class, () -> oneValueAccumulator.sampleVariance());

      }
    }
    return suite;
  }

  /** Throw {@link IllegalStateException} if {@link #createTestSuite()} can't be called yet. */
  protected void checkCanCreate() {
    if (subjectGenerator == null) {
      throw new IllegalStateException("Call using() before createTestSuite().");
    }
    if (name == null) {
      throw new IllegalStateException("Call named() before createTestSuite().");
    }

  public void testSampleCovariance() {
    assertThrows(IllegalStateException.class, () -> emptyAccumulator.sampleCovariance());
    assertThrows(
        IllegalStateException.class,
        () -> emptyAccumulatorByAddAllEmptyPairedStats.sampleCovariance());
    assertThrows(IllegalStateException.class, () -> oneValueAccumulator.sampleCovariance());
    assertThrows(
        IllegalStateException.class,

   * when hasNext() is false, so that next() throws a NoSuchElementException, then subsequent calls
   * to remove() will incorrectly throw an IllegalStateException, instead of removing the last
   * element returned.
   *
   * <p>See <a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6529795">Sun bug 6529795</a>
   */

  public void testSampleVariance() {
    assertThrows(IllegalStateException.class, () -> emptyAccumulator.sampleVariance());
    assertThrows(
        IllegalStateException.class, () -> emptyAccumulatorByAddAllEmptyIterable.sampleVariance());
    assertThrows(
        IllegalStateException.class, () -> emptyAccumulatorByAddAllEmptyStats.sampleVariance());
    assertThrows(IllegalStateException.class, () -> oneValueAccumulator.sampleVariance());

  }

  public void testPearsonsCorrelationCoefficient() {
    assertThrows(
        IllegalStateException.class, () -> EMPTY_PAIRED_STATS.pearsonsCorrelationCoefficient());
    assertThrows(
        IllegalStateException.class, () -> ONE_VALUE_PAIRED_STATS.pearsonsCorrelationCoefficient());
    assertThrows(
        IllegalStateException.class,
        () -> createSingleStats(Double.POSITIVE_INFINITY, 1.23).pearsonsCorrelationCoefficient());