HashCode unused = sink.hash();
    sink.assertInvariants(4);
    sink.assertBytes(new byte[] {1, 2, 3, 4});
  }

  public void testDouble() {
    Sink sink = new Sink(8);
    sink.putDouble(Double.longBitsToDouble(0x0807060504030201L));
    HashCode unused = sink.hash();
    sink.assertInvariants(8);
    sink.assertBytes(new byte[] {1, 2, 3, 4, 5, 6, 7, 8});
  }

  public void testCorrectExceptions() {

        fractionalBuilder.add(d * scale).add(-d * scale);
      }
    }
    for (int i = Double.MIN_EXPONENT; i <= Double.MAX_EXPONENT; i++) {
      for (int direction : new int[] {1, -1}) {
        double d = Double.longBitsToDouble(Double.doubleToLongBits(Math.scalb(1.0, i)) + direction);
        // Math.nextUp/nextDown
        if (d != Math.rint(d)) {
          fractionalBuilder.add(d);
        }
      }
    }
    for (double d :