import yaml
import os
from mock import MagicMock
from contextlib import contextmanager


def spy(method_to_decorate):
    mock = MagicMock()

    def wrapper(self, *args, **kwargs):
        mock(*args, **kwargs)
        return method_to_decorate(self, *args, **kwargs)

    wrapper.mock = mock
    return wrapper


def load_stage_file(path):
    with open(path, "r") as fobj:
        return yaml.safe_load(fobj)


@contextmanager
def cd(newdir):
    prevdir = os.getcwd()
    os.chdir(os.path.expanduser(newdir))
    try:
        yield
    finally:
        os.chdir(prevdir)