mock.patchの検証

hoge.py

import threading
import time
from unittest import mock


class Hoge:
    b = 10


a = Hoge()


def foo():
    print(f'[Foo]before-patch: {a.b}')
    with mock.patch('__main__.a.b', 100):
        print(f'[Foo]in-patch1: {a.b}')
        time.sleep(1)
        print(f'[Foo]in-patch2: {a.b}')
    print(f'[Foo]after-patch: {a.b}')


def bar():
    for _ in range(10):
        print(f'[Bar] {a.b}')
        time.sleep(0.3)


t = threading.Thread(target=foo)
t.start()

bar()
t.join()

stdout

[Foo]before-patch: 10
[Bar] 10
[Foo]in-patch1: 100
[Bar] 100
[Bar] 100
[Bar] 100
[Foo]in-patch2: 100
[Foo]after-patch: 10
[Bar] 10
[Bar] 10
[Bar] 10
[Bar] 10
[Bar] 10
[Bar] 10