Class LsofFdLeakChecker

src/_pytest/pytester.py:122–192

class LsofFdLeakChecker:
    def get_open_files(self) -> list[tuple[str, str]]:
        if sys.version_info >= (3, 11):
            # New in Python 3.11, ignores utf-8 mode
            encoding = locale.getencoding()
        else:
            encoding = locale.getpreferredencoding(False)
        out = subprocess.run(
            ("lsof", "-Ffn0", "-p", str(os.getpid())),
            stdout=subprocess.PIPE,
            stderr=subprocess.DEVNULL,
            check=True,
            text=True,
            encoding=encoding,
        ).stdout

        def isopen(line: str) -> bool:
            return line.startswith("f") and (
                "deleted" not in line
                and "mem" not in line
                and "txt" not in line
                and "cwd" not in line
            )

        open_files = []

        for line in out.split("\n"):
            if isopen(line):
                fields = line.split("\0")
                fd = fields[0][1:]
                filename = fields[1][1:]
                if filename in IGNORE_PAM:
                    continue
                if filename.startswith("/"):
                    open_files.append((fd, filename))

        return open_files

    def matching_platform(self) -> bool:
        try:
            subprocess.run(("lsof", "-v"), check=True)
        except (OSError, subprocess.CalledProcessError):
            return False
        else:
            return True

    @hookimpl(wrapper=True, tryfirst=True)
    def pytest_runtest_protocol(self, item: Item) -> Generator[None, object, object]:
        lines1 = self.get_open_files()
        try:
            return (yield)
        finally:
            if hasattr(sys, "pypy_version_info"):
                gc.collect()
            lines2 = self.get_open_files()

            new_fds = {t[0] for t in lines2} - {t[0] for t in lines1}
            leaked_files = [t for t in lines2 if t[0] in new_fds]