Set<Object> keys = cache.asMap().keySet();
      assertThrows(NullPointerException.class, () -> keys.toArray((Object[]) null));
      checkEmpty(cache);
    }
  }

  public void testKeySet_addNotSupported() {
    for (LoadingCache<Object, Object> cache : caches()) {
      assertThrows(UnsupportedOperationException.class, () -> cache.asMap().keySet().add(1));

      assertThrows(

    graph.putEdgeValue(1, 2, "A");
    IllegalArgumentException e =
        assertThrows(
            IllegalArgumentException.class,
            () -> graph.edgeValueOrDefault(EndpointPair.unordered(1, 2), "default"));
    assertThat(e).hasMessageThat().contains(ENDPOINTS_MISMATCH);
    e =
        assertThrows(
            IllegalArgumentException.class,

  }

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

  }

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

  public void testParse_weakValuesCannotHaveValue() {
    assertThrows(IllegalArgumentException.class, () -> parse("weakValues=true"));
  }

  public void testParse_repeatedValueStrength() {
    assertThrows(IllegalArgumentException.class, () -> parse("softValues, softValues"));

    assertThrows(IllegalArgumentException.class, () -> parse("softValues, weakValues"));

  }

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

    for (int index : new int[] {-1, SIZE}) {
      assertThrows(IndexOutOfBoundsException.class, () -> aa.get(index));
      assertThrows(IndexOutOfBoundsException.class, () -> aa.set(index, 1.0));
      assertThrows(IndexOutOfBoundsException.class, () -> aa.lazySet(index, 1.0));
      assertThrows(IndexOutOfBoundsException.class, () -> aa.compareAndSet(index, 1.0, 2.0));

    StopFailingService service = new StopFailingService();
    assertThrows(IllegalStateException.class, () -> service.failureCause());
    service.startAsync().awaitRunning();
    assertThrows(IllegalStateException.class, () -> service.failureCause());
    IllegalStateException e =
        assertThrows(IllegalStateException.class, () -> service.stopAsync().awaitTerminated());

    assume().that(graphIsMutable()).isTrue();

    addEdge(N1, N2, E12);
    IllegalArgumentException e =
        assertThrows(
            IllegalArgumentException.class, () -> networkAsMutableNetwork.addEdge(N4, N5, E12));
    assertThat(e).hasMessageThat().contains(ERROR_REUSE_EDGE);
    e = assertThrows(IllegalArgumentException.class, () -> addEdge(N2, N1, E12));
    assertThat(e).hasMessageThat().contains(ERROR_REUSE_EDGE);
  }

    ImmutableSortedMultiset.Builder<String> builder = ImmutableSortedMultiset.naturalOrder();
    assertThrows(NullPointerException.class, () -> builder.add((String) null));
  }

  public void testBuilderAddAllHandlesNullsCorrectly() {
    {
      ImmutableSortedMultiset.Builder<String> builder = ImmutableSortedMultiset.naturalOrder();
      assertThrows(NullPointerException.class, () -> builder.addAll((Collection<String>) null));
    }