Python io.BytesIO binary stream as {out,err}_stream container

Start with invoke/runners.py, especially handle_stdout and write_our_output, and the run wrapper in invoke/util.py. Determine how out_stream and err_stream handle binary file-like objects in synchronous and asynchronous execution; done means BytesIO receives real-time output without the reported TypeError or requiring filesystem storage.

Hi,
I'm trying to capture and process in real time the output of a command started with run in asynchronous mode, with the out_stream option using an in-memory buffer. So I've used the built-in io library with BytesIO class: is this class supported in your Invoke implementation?

I post the following code example:

import io
import time
from invoke import run

out = io.BytesIO()

run('ls -la && sleep 2 && ls -la', warn=True, pty=True, out_stream=out, asynchronous=True)

time.sleep(1)

while True:
    myline=out.readline()
    print(myline)
    time.sleep(1)
    if not myline:
        out.close()
        break

If you run this code, as you can see, it won't print any binary data despite readline() method is supported by BytesIO class. It seems run method is not writing in the out binary (buffer) object. Furthermore if you put asynchronous to False the script exits with this error:

Traceback (most recent call last):

  File "/usr/local/lib/python3.9/dist-packages/invoke/util.py", line 237, in run
    super(ExceptionHandlingThread, self).run()

  File "/usr/lib/python3.9/threading.py", line 892, in run
    self._target(*self._args, **self._kwargs)

  File "/usr/local/lib/python3.9/dist-packages/invoke/runners.py", line 756, in handle_stdout
    self._handle_output(

  File "/usr/local/lib/python3.9/dist-packages/invoke/runners.py", line 730, in _handle_output
    self.write_our_output(stream=output, string=data)

  File "/usr/local/lib/python3.9/dist-packages/invoke/runners.py", line 718, in write_our_output
    stream.write(encode_output(string, self.encoding))

TypeError: a bytes-like object is required, not 'str'

AFAIK io.BytesIO() is not a 'str' object, it's a binary stream using an in-memory bytes buffer.

Is it possible to use a BytesIO type (for binary data) as a buffer container of {out,err}_stream? If not, is it possible to implement it in Invoke, in order to process the output stream in real time (not when the command, that is very long in my project, has finished) without using filesystem (file-like) objects?

Thank you in advance for your help!

Roberto