Fix problem with objects with invalid repr

[tamarinvs19]

Description

Fix problem with serialization of "unserializable" objects (for example, logging.Logger or socket.socket). We cannot serialize it so cannot generate tests but in previous version we generated tests with string representation of these objects (<Logger x (NOSET)> or <socket.socket ... >).

In future we can use mocks at these situations.

Fixes #1822

How to test

Manual tests

See #1822 (comment)
Expected: no one test have been generated

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[tochilinak]

I looked this version of utbot_executor and I don't like the way you check whether an object has correct repr:

if not isinstance(py_object, str) and r.startswith('<') and r.endswith('>')

One can override __repr__ method of their (unserializable) object so that it will pass this check.

From CPython sources we see that there is a finite number of types that are not serialized with __reduce__ method: https://github.com/python/cpython/blob/main/Lib/pickle.py#L734

Maybe we should just list them?

[tamarinvs19]

I didn't find socket.socket and logging.Logger in this file... For example, logging.Logger has method __reduce__ but it sometimes raises error pickle.PicklingError

[tamarinvs19]

Maybe we can call eval and check that we got the same type (but not the same value because object can be serializable and incomparable)

[tochilinak]

But socket.socket and logging.Logger can never be serialized by pickle.

[tochilinak]

eval check may be tricky because of modules that are needed to be imported

[tamarinvs19]

But socket.socket and logging.Logger can never be serialized by pickle.

I can pickle logging.Logger:

import logging
import pickle

pickle.dumps(logging.getLogger())

[tamarinvs19]

eval check may be tricky because of modules that are needed to be imported

I agree, it can be a problem

[tochilinak]

That is interesting...

[tamarinvs19]

I added list of repr-able objects from pickle source code (tamarinvs19/utbot_executor@e6dc858)

[tochilinak]

I think there is a problem with None.

Had a closer look

[tamarinvs19]

I think there is a problem with None.

Fixed tamarinvs19/utbot_executor@62e618b