Inconsistant behavior of .readable() and .writable() on io.IOBase

Bug report

The methods .readble() and .writable() on io.IOBase should return a boolean representing if the file can be read from/written to. However, calling .readable() on a closed IO file object causes a ValueError, whereas calling .writable() on a closed file returns False if the file was opened with just read permissions, but raises ValueError if it was opened with read and write permissions.

Make a folder with a text file in, then run:

f = open("hello.txt")
print(f.writable())
print(f.readable())
f.close()
print(f.writable())
print(f.readable())

This will output:

False
True
False
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: I/O operation on closed file

Then doing a similar thing, but with w+ permissions

f = open("hello.txt", "w+")
print(f.writable())
print(f.readable())
f.close()
print(f.writable())
print(f.readable())

Will output

True
True
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: I/O operation on closed file

Your environment

• CPython versions tested on: 3.10.4
• Operating system and architecture: Windows 64bit

Commencez par reproduire les deux exemples de fichiers fermés présents dans l’issue, puis examinez les points d’entrée io.IOBase.readable() et writable() ainsi que les tests associés. La tâche est terminée lorsque les deux méthodes ont un comportement cohérent et documenté pour les fichiers fermés, tout en préservant les résultats attendus pour les fichiers ouverts.