class DummyDevice:
    """DummyDevice base class, you should inherit from this and call
    `super().__init__(args, kwargs)` to save the original state.

    This class provides helpers to test simple devices, for more complex
    ones you will want to extend the `return_values` accordingly.
    The basic idea is that the overloaded send() will read a wanted response
    based on the call from `return_values`.

    For changing values :func:`_set_state` will use :func:`pop()` to extract
     the first parameter and set the state accordingly.

    For a very simple device the following is enough, see :class:`TestPlug`
     for complete code.

    .. code-block::
        self.return_values = {
            "get_prop": self._get_state,
            "power": lambda x: self._set_state("power", x)
        }

    """
    def __init__(self, *args, **kwargs):
        self.start_state = self.state.copy()

    def send(self, command: str, parameters=None, retry_count=3):
        """Overridden send() to return values from `self.return_values`."""
        return self.return_values[command](parameters)

    def _reset_state(self):
        """Revert back to the original state."""
        self.state = self.start_state.copy()

    def _set_state(self, var, value):
        """Set a state of a variable,
        the value is expected to be an array with length of 1."""
        # print("setting %s = %s" % (var, value))
        self.state[var] = value.pop(0)

    def _get_state(self, props):
        """Return wanted properties"""
        return [self.state[x] for x in props if x in self.state]