mock.py 文件源码

def mock_open(mock=None, read_data=''):
        """
        A helper function to create a mock to replace the use of `open`. It works
        for `open` called directly or used as a context manager.

        The `mock` argument is the mock object to configure. If `None` (the
        default) then a `MagicMock` will be created for you, with the API limited
        to methods or attributes available on standard file handles.

        `read_data` is a string for the `read` methoddline`, and `readlines` of the
        file handle to return.  This is an empty string by default.
        """
        def _readlines_side_effect(*args, **kwargs):
            if handle.readlines.return_value is not None:
                return handle.readlines.return_value
            return list(_data)

        def _read_side_effect(*args, **kwargs):
            if handle.read.return_value is not None:
                return handle.read.return_value
            return type(read_data)().join(_data)

        def _readline_side_effect():
            if handle.readline.return_value is not None:
                while True:
                    yield handle.readline.return_value
            for line in _data:
                yield line

        global file_spec
        if file_spec is None:
            import _io
            file_spec = list(set(dir(_io.TextIOWrapper)).union(set(dir(_io.BytesIO))))

        if mock is None:
            mock = MagicMock(name='open', spec=open)

        handle = MagicMock(spec=file_spec)
        handle.__enter__.return_value = handle

        _data = _iterate_read_data(read_data)

        handle.write.return_value = None
        handle.read.return_value = None
        handle.readline.return_value = None
        handle.readlines.return_value = None

        handle.read.side_effect = _read_side_effect
        handle.readline.side_effect = _readline_side_effect()
        handle.readlines.side_effect = _readlines_side_effect

        mock.return_value = handle
        return mock