pypy_list_pop.py

# $ python --version
#Python 3.5.3 (a39af0be3a22, Jun 05 2017, 20:18:00)
#[PyPy 5.8.0-beta0 with GCC 6.2.0 20160901]
#
# The problem has been discovered here:
# https://travis-ci.org/aio-libs/aioredis/jobs/245293341
#
# TL;DR:
# pop() call from a list object created in C-extension
# returns None for the first call,
# subscequent calls return expected values

import hiredis  # version v0.2.0;

r = hiredis.Reader()


def get_list():
    # bulk array response with two items;
    r.feed(b'*2\r\n+Item 1\r\n+Item 2\r\n')
    return r.gets()


l = get_list()

assert isinstance(l, list)
assert l == [b'Item 1', b'Item 2']
item = l.pop()
# This line fails!
assert item is not None and item == b'Item 2', (item, type(item))
item = l.pop()
assert item is not None and item == b'Item 1', (item, type(item))


# Another try, pop from left

l = get_list()

assert isinstance(l, list)
assert l == [b'Item 1', b'Item 2']
item = l.pop(0)
# This line fails!
assert item is not None and item == b'Item 2', (item, type(item))
item = l.pop(0)
assert item is not None and item == b'Item 1', (item, type(item))


# Another try, pop by index

l = get_list()

assert isinstance(l, list)
assert l == [b'Item 1', b'Item 2']
item = l.pop(1)
# This line fails!
assert item is not None and item == b'Item 2', (item, type(item))
item = l.pop(0)
assert item is not None and item == b'Item 1', (item, type(item))

setup.sh

#!/bin/bash

# wget -c https://bitbucket.org/pypy/pypy/downloads/pypy3-v5.7.1-linux64.tar.bz2
wget -c https://bitbucket.org/pypy/pypy/downloads/pypy3-v5.8.0-linux64.tar.bz2

# tar -xjf pypy3-v5.7.1-linux64.tar.bz2
 tar -xjf pypy3-v5.8.0-linux64.tar.bz2

# ./pypy3-v5.7.1-linux64/bin/pypy3 -m venv ./tmp
./pypy3-v5.8.0-linux64/bin/pypy3 -m venv ./tmp
source ./tmp/bin/activate

pip install -v --force-reinstall --no-binary=:all: hiredis

python pypy_list_pop.py