Mini Shell

class TestPath:
    _path_using_io = (
        'abspath', 'curdir', 'exists', 'expanduser', 'expandvars',
        'getatime', 'getctime', 'getmtime', 'getsize',
        'isfile', 'islink', 'ismount', 'realpath',
        'samefile', 'sameopenfile', 'samestat',
        'walk',

    )

    def __init__(self, os):
        for name in dir(os.path):
            if (not name.startswith('_') and
                    name not in self._path_using_io):
                setattr(self, name, getattr(os.path, name))


class TestIO:
    def __init__(self, mod):
        os = mod._root.os
        for name in mod.os_common:
            setattr(self, name, getattr(os, name))
        self.path = TestPath(os)
        self.files = {}
        self.tempno = 0

    def access(self, name, mode):
        if name in self.files:
            return True
        return False

    def listdir(self, name):
        li = []
        name = self.path.join(name, '')
        for k in self.files:
            if k.startswith(name):
                rest = k[len(name):]
                if rest:
                    li.append(rest)
        return li

    def mkdtemp(self):
        self.tempno += 1
        return '/tmp/xyz%d' % self.tempno

    def read_file(self, name):
        return self.files[name]

    def remove(self, name):
        try:
            del self.files[name]
        except KeyError:
            raise IOError('No such file: %r' % name)

    def rename(self, src, tgt):
        try:
            data = self.files[src]
        except KeyError:
            raise IOError('No such file: %r' % src)
        del self.files[src]
        self.files[tgt] = data

    def rmdir(self, name):
        pass

    def write_file(self, name, text):
        self.files[name] = text


class RealIO:
    def __init__(self, mod):
        os = mod._root.os
        for name in mod.os_common:
            setattr(self, name, getattr(os, name))
        self.path = os.path
        self.listdir = os.listdir
        self.makedirs = os.makedirs
        self.mkdtemp = mod._root.tempfile.mkdtemp
        self.rmdir = os.rmdir
        self.access = os.access
        self.chdir = os.chdir
        self.remove = os.remove
        self.rename = os.rename

    def read_file(self, name):
        with open(name) as f:
            return f.read()

    def write_file(self, name, data):
        with open(name, 'w') as f:
            f.write(data)


class _GLUECLAMP_:

    _setable_ = 'IO',

    os_common = ('R_OK', 'W_OK', 'X_OK')

    def _get_IO(self):
        return RealIO(self)

    def set_IO(self, IO):
        self.IO = IO

    def set_test_mode(self):
        self.set_IO(TestIO(self))