Unit tests of the Xiaomi Power Strip extended. (#136)

* Property "current" re-introduced for completeness.

miio/powerstrip.py

@@ -37,6 +37,13 @@ def temperature(self) -> float:
         """Current temperature."""
         return self.data["temperature"]
 
+    @property
+    def current(self) -> Optional[float]:
+        """Current, if available. Meaning and voltage reference unknown."""
+        if self.data["current"] is not None:
+            return self.data["current"]
+        return None
+
     @property
     def load_power(self) -> Optional[float]:
         """Current power load, if available."""

miio/tests/test_powerstrip.py

@@ -1,5 +1,6 @@
 from unittest import TestCase
 from miio import PowerStrip
+from miio.powerstrip import PowerMode
 from .dummies import DummyDevice
 import pytest
 
@@ -10,12 +11,13 @@ def __init__(self, *args, **kwargs):
             'power': 'on',
             'mode': 'normal',
             'temperature': 32.5,
-            'current': 123,
+            'current': 25.5,
             'power_consume_rate': 12.5,
         }
         self.return_values = {
             'get_prop': self._get_state,
             'set_power': lambda x: self._set_state("power", x),
+            'set_power_mode': lambda x: self._set_state("mode", x),
         }
         super().__init__(args, kwargs)
 
@@ -54,10 +56,34 @@ def test_status(self):
         self.device._reset_state()
 
         assert self.is_on() is True
+        assert self.state().mode == PowerMode(self.device.start_state["mode"])
         assert self.state().temperature == self.device.start_state["temperature"]
+        assert self.state().current == self.device.start_state["current"]
         assert self.state().load_power == self.device.start_state["power_consume_rate"]
 
     def test_status_without_power_consume_rate(self):
-        del self.device.state["power_consume_rate"]
+        self.device._reset_state()
 
+        self.device.state["power_consume_rate"] = None
         assert self.state().load_power is None
+
+    def test_status_without_current(self):
+        self.device._reset_state()
+
+        self.device.state["current"] = None
+        assert self.state().current is None
+
+    def test_status_without_mode(self):
+        self.device._reset_state()
+
+        self.device.state["mode"] = None
+        assert self.state().mode is None
+
+    def test_set_power_mode(self):
+        def mode():
+            return self.device.status().mode
+
+        self.device.set_power_mode(PowerMode.Eco)
+        assert mode() == PowerMode.Eco
+        self.device.set_power_mode(PowerMode.Normal)
+        assert mode() == PowerMode.Normal