message: test: introduce TestNode.debug_log_bytes
diff: @@ -392,14 +392,17 @@ class TestNode():
  def debug_log_path(self) -> Path:
  return self.chain_path / 'debug.log'
  + def debug_log_bytes(self) -> int:
  + with open(self.debug_log_path, encoding='utf-8') as dl:
  + dl.seek(0, 2)
  + return dl.tell()
  +
  @contextlib.contextmanager
  def assert_debug_log(self, expected_msgs, unexpected_msgs=None, timeout=2):
  if unexpected_msgs is None:
  unexpected_msgs = []
  time_end = time.time() + timeout * self.timeout_factor
  - with open(self.debug_log_path, encoding='utf-8') as dl:
  - dl.seek(0, 2)
  - prev_size = dl.tell()
  + prev_size = self.debug_log_bytes()
  yield
  