Stub Read method.

def read(self, length, dummy=None):
    """Stub Read method."""
    assert not self.closed
    data = self.expected_read_data.pop(0)
    if length < len(data):
      raise ValueError(
          'Overflow packet length. Read %d bytes, got %d bytes: %s',
          length, len(data), self._dotify(data))
    return data