// nothing really to assert?
    assertSame(CharStreams.nullWriter(), CharStreams.nullWriter());
  }

  /**
   * Returns a reader wrapping the given reader that only reads half of the maximum number of
   * characters that it could read in read(char[], int, int).
   */
  private static Reader newNonBufferFillingReader(Reader reader) {
    return new FilterReader(reader) {
      @Override

        @DisplayName("Should handle various capacity and free space values")
        @CsvSource({ "0, 0", "1024, 512", "1048576, 524288", "1073741824, 536870912", "9223372036854775807, 4611686018427387903", // Long.MAX_VALUE and half
                "-1, -1", // Negative values (edge case)
                "100, 200" // Free space greater than capacity (edge case)
        })
        void shouldHandleVariousValues(long capacity, long free) {

FE20..FE23    ; valid                                  # 1.1  COMBINING LIGATURE LEFT HALF..COMBINING DOUBLE TILDE RIGHT HALF
FE24..FE26    ; valid                                  # 5.1  COMBINING MACRON LEFT HALF..COMBINING CONJOINING MACRON
FE27..FE2D    ; valid                                  # 7.0  COMBINING LIGATURE LEFT HALF BELOW..COMBINING CONJOINING MACRON BELOW

        int logFloor = (Long.SIZE - 1) - leadingZeros;
        return logFloor + lessThanBranchFree(cmp, x);
    }
    throw new AssertionError("impossible");
  }

  /** The biggest half power of two that fits into an unsigned long */
  @VisibleForTesting static final long MAX_POWER_OF_SQRT2_UNSIGNED = 0xB504F333F9DE6484L;

  /**

    Builder<Integer, String> builder = ImmutableMap.builder();
    Map<Integer, String> expected = new LinkedHashMap<>();
    for (int i = 0; i < 1000; i++) {
      // Truncate to even key, so we have put(0, "0") then put(0, "1"). Half the entries are
      // duplicates.
      Integer key = i & ~1;
      String value = String.valueOf(i);
      builder.put(key, value);
      expected.put(key, value);
    }

  }

  /*
   * Whenever an implementation uses `instanceof` on a parameter instance, the test has to know that
   * (so much for "black box") and try instances that both do and don't pass the check. The "don't"
   * half of that is more awkward to arrange...
   */
  private static <T> Iterable<T> iterable(Collection<T> collection) {
    // return collection::iterator;
    return new Iterable<T>() {
      @Override

                            if (proc != processor) {
                                errorCount.incrementAndGet();
                            }

                            // Occasionally update (half the threads)
                            if (threadId % 2 == 0 && j % 10 == 0) {
                                testRule.setRuleId("concurrentRule");
                                testRule.setResponseProcessor(processor);

      for (Thread hook : hooks) {
        hook.start();
      }
      for (Thread hook : hooks) {
        hook.join();
      }
    }
  }

  /* Half of a 1-second timeout in nanoseconds */
  private static final long HALF_SECOND_NANOS = NANOSECONDS.convert(1L, SECONDS) / 2;

  public void testShutdownAndAwaitTermination_immediateShutdown() throws Exception {

        // Set a reasonable TTL
        auth.setAuthenticationTTL(1000); // 1 second

        // Should not be expired immediately
        assertFalse(auth.isExpired());

        // Wait half the TTL
        Thread.sleep(500);
        assertFalse(auth.isExpired());

        // Reset timestamp
        long beforeReset = System.currentTimeMillis();
        auth.resetAuthenticationTimestamp();

  }

  /*
   * Whenever an implementation uses `instanceof` on a parameter instance, the test has to know that
   * (so much for "black box") and try instances that both do and don't pass the check. The "don't"
   * half of that is more awkward to arrange...
   */
  private static <T> Iterable<T> iterable(Collection<T> collection) {
    // return collection::iterator;
    return new Iterable<T>() {
      @Override