如何检测在 Python 模块导入上执行的顶级 print() 和日志记录调用？

Question

我想检测对print()和logging （例如logging.info() ）的调用是顶级可访问的，即在模块加载时执行，如果找到则构建失败。

我维护其他团队经常提交的服务，因此我希望将其作为 CI 中的某种 lint-check。 我怎样才能做到这一点？

我不关心非顶级调用（例如函数内部的调用）。 如果他们真的愿意，我想继续允许其他团队这样做，因为当他们执行自己的代码时。

到目前为止，我已经尝试/遇到了几件事但没有成功，通常是我关心的所有 python 文件的动态import_module然后：

• pytest的capsys / capfd功能： https://github.com/pytest-dev/pytest/issues/5997#issuecomment-1028710193
  例如：

# foo.py
print("hello")

from importlib import import_module

def test_does_not_print(capfd):
    import_module('foo')
    out, err = capfd.readouterr()

    assert out == ""  # surprise: this will pass

• 走过去： ast ://stackoverflow.com/a/25249854/234593 （很难判断顶级是否可达）
• 模拟 Python 的内置打印 function

Answer 1

我已经能够通过运行时在一个可以在 CI 期间运行的独立脚本中对print和logging.info函数进行monkeypatching来实现这一点，例如：

import builtins
from contextlib import contextmanager
import functools as ft
from importlib import import_module
import logging
import os
import sys

orig_print = builtins.print
orig_info, orig_warning, orig_error, orig_critical = logging.info, logging.warning, logging.error, logging.critical
NO_ARG = object()
sys.path.insert(0, 'src')


def main():
    orig_print("Checking files for print() & logging on import...")
    for path in files_under_watch():
        orig_print("  " + path)
        output = detect_toplevel_output(path)
        if output:
            raise SyntaxWarning(f"Top-level output (print & logging) detected in {path}: {output}")


def files_under_watch():
    for root, _, files in os.walk('src'):
        for file in files:
            if should_watch_file(file):  # your impl here
                yield os.path.join(root, file)


def detect_toplevel_output(python_file_path):
    with capture_print() as printed, capture_logging() as logged:
        module_name = python_file_path[:-3].replace('/', '.')
        import_module(module_name)

    output = {'print': printed, 'logging': logged}
    return {k: v for k, v in output.items() if v}


@contextmanager
def capture_print():
    calls = []

    @ft.wraps(orig_print)
    def captured_print(*args, **kwargs):
        calls.append((args, kwargs))
        return orig_print(*args, **kwargs)

    builtins.print = captured_print
    yield calls
    builtins.print = orig_print


@contextmanager
def capture_logging():
    calls = []

    @ft.wraps(orig_info)
    def captured_info(*args, **kwargs):
        calls.append(('info', args, kwargs))
        return orig_info(*args, **kwargs)

    @ft.wraps(orig_warning)
    def captured_warning(*args, **kwargs):
        calls.append(('warning', args, kwargs))
        return orig_warning(*args, **kwargs)

    @ft.wraps(orig_error)
    def captured_error(*args, **kwargs):
        calls.append(('error', args, kwargs))
        return orig_error(*args, **kwargs)

    @ft.wraps(orig_critical)
    def captured_critical(*args, **kwargs):
        calls.append(('critical', args, kwargs))
        return orig_critical(*args, **kwargs)

    logging.info, logging.warning, logging.error, logging.critical = captured_info, captured_warning, captured_error, captured_critical
    yield calls
    logging.info, logging.warning, logging.error, logging.critical = orig_info, orig_warning, orig_error, orig_critical


if __name__ == '__main__':
    main()