Can't use pickled function inside a pytest test

Question

So I have this scenario, I create a function that depends on pandas , which I then pickle and then reload and try to run and gives error that pd is not defined :

def pandize(arg):
    pd.DataFrame('a')

import dill
with open('pandize.pkl', 'wb') as f:
    dill.dump(pandize, f)

with open('pandize.pkl', 'rb') as f:
    p = dill.load(f)

p(1)
NameError: name 'pd' is not defined

After that I import pandas as pd and the code gets called.

But I can't replicate this behaviour inside a pytest test function. Even if I add the import pandas as pd I'm still getting the NameError pd is not defined . Any ideas why?

Answer 1

As pointed out by @MrBeanBremen in linked question in the comment, importing __main__ and then defining pandas in __main__ made the trick:

import pandas as pd
import __main__
__main__.pd = pd

with open('pandize.pkl', 'rb') as f:
    p = dill.load(f)

p(1)

This setup doesn't cause the test to fail with a NameError any more.