Despite setting PYTHON_VERSION: "3.8.0", appveyor used Python 2.7.
https://ci.appveyor.com/project/duyue/hiredis-py/builds/28350884/job/xbid8ymbjdt08r3y#L8

It looks like they don't support Python 3.8 yet: appveyor/ci#3142

LGTM

I see there's a workaround from the link you provided above appveyor/ci#3142 (comment), would mind adding it？

I've added the workaround and now Python 3.8 is available:

python --version
Python 3.8.0

But now the tests are failing:

Executing: python test.py
Traceback (most recent call last):
  File "test.py", line 4, in <module>
    import test
  File "C:\projects\hiredis-py\test\__init__.py", line 11, in <module>
    from . import reader
  File "C:\projects\hiredis-py\test\reader.py", line 3, in <module>
    import hiredis
ImportError: DLL load failed while importing hiredis: The parameter is incorrect.
Command exited with code 1

This is probably related to https://bugs.python.org/issue36085 (new in Python 3.8) (see esp. python/cpython#12302). I'm not familiar with Windows and have no idea how to properly fix this. :(

I am not familiar with Windows, too. I tried but without success.
However, when I apply these changes in this PR to another project, it works fine.
Don't know why..

🚀 Python 3.8 is now available on AppVeyor:

• Python 3.8.0 appveyor/ci#3142 (comment)

Workaround no longer needed.
ImportError still exists, need to investigate...

I've found the cause, it's in test/__init__.py:

# Add path to hiredis.so load path
path = glob.glob("build/lib*-%s/hiredis" % majorminor)[0]
sys.path.insert(0, path)

This somehow makes Python 3.8 on AppVeyor windows raise ImportError.