try {
      entrySet.add((Entry<K, V>) entryToAdd);
      fail("Expected UnsupportedOperationException or NullPointerException.");
    } catch (UnsupportedOperationException | NullPointerException e) {
      // Expected.
    }
    assertInvariants(map);

    try {
      entrySet.addAll(singleton((Entry<K, V>) entryToAdd));
      fail("Expected UnsupportedOperationException or NullPointerException.");

    Subscriber subscriber = Subscriber.create(bus, this, method);

    InvocationTargetException expected =
        assertThrows(
            InvocationTargetException.class,
            () -> subscriber.invokeSubscriberMethod(FIXTURE_ARGUMENT));
    assertThat(expected).hasCauseThat().isInstanceOf(IntentionalException.class);
  }

  public void testInvokeSubscriberMethod_errorPassthrough() throws Throwable {

  @Test
  fun readIndexedHeaderFieldIndex0() {
    bytesIn.writeByte(0x80) // == Indexed - Add idx = 0
    assertFailsWith<IOException> {
      hpackReader!!.readHeaders()
    }.also { expected ->
      assertThat(expected.message).isEqualTo("index == 0")
    }
  }

  // Example taken from twitter/hpack DecoderTest.testIllegalIndex
  @Test
  fun readIndexedHeaderFieldTooLargeIndex() {

  @CollectionSize.Require(SEVERAL)
  @CollectionFeature.Require(value = KNOWN_ORDER, absent = NON_STANDARD_TOSTRING)
  public void testToString_sizeSeveral() {
    String expected = copyToList(getOrderedElements()).toString();
    assertEquals("collection.toString() incorrect", expected, collection.toString());
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  public void testToString_null() {

  @CollectionSize.Require(SEVERAL)
  @CollectionFeature.Require(value = KNOWN_ORDER, absent = NON_STANDARD_TOSTRING)
  public void testToString_sizeSeveral() {
    String expected = copyToList(getOrderedElements()).toString();
    assertEquals("collection.toString() incorrect", expected, collection.toString());
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  public void testToString_null() {

    private boolean expectCall = false;
    private final CountDownLatch calledCountDown = new CountDownLatch(1);

    @Override
    public void run() {
      assertTrue("Listener called before it was expected", expectCall);
      assertFalse("Listener called more than once", wasCalled());
      calledCountDown.countDown();
    }

    void expectCall() {
      assertFalse("expectCall is already true", expectCall);

    assertThat(actual.toString()).isEqualTo(expected.toString());
    assertThat(actual.getName()).isEqualTo(expected.getName());
    assertEquals(expected.getGenericDeclaration(), actual.getGenericDeclaration());
    if (!Types.NativeTypeVariableEquals.NATIVE_TYPE_VARIABLE_ONLY) {
      assertEquals(actual.toString(), expected.hashCode(), actual.hashCode());
    }

                  } catch (ExecutionException expected) {
                  }
                  try {
                    peeker.getDone(nonInput);
                    fail("Peeker should not be able to peek into non-input ClosingFuture.");
                  } catch (IllegalArgumentException expected) {
                  }
                  capturedPeeker.set(peeker);

    Subscriber subscriber = Subscriber.create(bus, this, method);

    InvocationTargetException expected =
        assertThrows(
            InvocationTargetException.class,
            () -> subscriber.invokeSubscriberMethod(FIXTURE_ARGUMENT));
    assertThat(expected).hasCauseThat().isInstanceOf(IntentionalException.class);
  }

  public void testInvokeSubscriberMethod_errorPassthrough() throws Throwable {

        chain.updateThrowsException = true;
        User user = createTestUser("testuser", "Test User");

        try {
            chain.update(user);
            fail("Expected exception to be thrown");
        } catch (RuntimeException e) {
            assertEquals("Update failed", e.getMessage());
        }

        assertEquals(1, chain.updateCalls.size());
    }