使用pytest进行单元测试时，遇到了需要测试日志输出的情况，查看了文档

https://docs.pytest.org/en/latest/how-to/capture-stdout-stderr.html

https://docs.pytest.org/en/latest/how-to/logging.html

然后试了一下，捕捉logger.info可以用caplog，获取print输出可用capsys，Demo如下：

- a.py

import logging

logger = logging.getLogger(__name__)
LOG_INFO = "I'm a teapot"
PRINT_MSG = "No thing to do."


def function_with_logger(msg=None):
    if msg is None:
        msg = LOG_INFO
    logger.info(msg)


def function_include_print():
    print(PRINT_MSG)

- test_a.py

import logging

from a import LOG_INFO, PRINT_MSG, function_include_print, function_with_logger


def test_logger(caplog):
    caplog.set_level(logging.INFO)
    function_with_logger()
    log_messages = [record.message for record in caplog.records]
    assert LOG_INFO in log_messages
    caplog.clear()
    function_with_logger("foo")
    assert "foo" in caplog.text


def test_print(capsys):
    function_include_print()
    captured = capsys.readouterr()
    assert PRINT_MSG in captured.out

- 验证：

pytest test_a.py