README.md

I learn about python and ground those lessons in the pytest codebase here.

Entry Point	Object	Lessons
searched (itertools.)?chain\(	resolve_package_path	- itertools.chain takes a variable number of iterables. - was likely chosen because it does not create a list in memory - Path has methods that do system calls. - reaching the end of multiple if not conditions is the same as 'If all conditions are true' - path.parents is a sequence of Paths

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resolve_package_path

#src/_pytest/pathlib.py
def resolve_package_path(path: Path) -> Optional[Path]:
    """Return the Python package path by looking for the last
    directory upwards which still contains an __init__.py.

    Returns None if it can not be determined.
    """
    result = None
    for parent in itertools.chain((path,), path.parents):
        if parent.is_dir():
            if not parent.joinpath("__init__.py").is_file():
                break
            if not parent.name.isidentifier():
                break
            result = parent
    return result

Observe that itertools.chain requires a variable number of iterable arguments.

Warning

Unpacking is eager.