private final CountDownLatch listenerLatch = new CountDownLatch(1);

  private volatile boolean throwException = false;

  private final ListenableFutureTask<Integer> task =
      ListenableFutureTask.create(
          () -> {
            runLatch.countDown();
            taskLatch.await();
            if (throwException) {
              throw new IllegalStateException("Fail");
            }
            return 25;

        }

        public void setPurgeCallCount(long count) {
            this.purgeCallCount = count;
        }

        public void setThrowException(boolean throwException) {
            this.throwException = throwException;
        }

        public void setExceptionMessage(String message) {
            this.exceptionMessage = message;
        }

        public long getPurgeExpiry() {

  private final CountDownLatch listenerLatch = new CountDownLatch(1);

  private volatile boolean throwException = false;

  private final ListenableFutureTask<Integer> task =
      ListenableFutureTask.create(
          () -> {
            runLatch.countDown();
            taskLatch.await();
            if (throwException) {
              throw new IllegalStateException("Fail");
            }
            return 25;

        queryRescorer = new QueryRescorer() {
            @Override
            public RescorerBuilder<?> evaluate(Map<String, Object> params) {
                if (params != null && params.containsKey("throwException")) {
                    throw new RuntimeException("Test exception");
                }
                return createMockRescorerBuilder();
            }
        };

        // Test normal case

          } else { // (c)
            readMoreChars();
          }
        } else if (result.isError()) {
          // Only reach here if a CharsetEncoder with non-REPLACE settings is used.
          result.throwException();
          return 0; // Not called.
        }
      }
    }
  }

  /** Returns a new CharBuffer identical to buf, except twice the capacity. */
  private static CharBuffer grow(CharBuffer buf) {