假如有这样一段代码要测试：

# hello.py
def welcome() -> str:
    name = input("What's your name? ").strip()
    if not name:
        return 'Welcome to Guangdong~'
    return f'Hi, {name}. You are welcome!'

测试代码可以这样写：

# test_hello.py
# pip install pytest pytest_mock
import pytest
from pytest_mock import MockerFixture
from hello import welcome

def test_welcome(
    # Use pytest-mock to mock user input
    # https://github.com/pytest-dev/pytest-mock
    mocker: MockerFixture,
):
    mocker.patch("builtins.input", return_value="")
    assert welcome() == 'Welcome to Guangdong~'
    mocker.patch("builtins.input", return_value=" ")
    assert welcome() == 'Welcome to Guangdong~'
    mocker.patch("builtins.input", return_value="Waket")
    assert welcome() == 'Hi, Waket. You are welcome!'
    mocker.patch("builtins.input", return_value="Joe")
    assert welcome() == 'Hi, Joe. You are welcome!'

运行：

pytest test_hello.py