Fix water_level calculation for humidifiers (#1140)

* Fix water level calculation

* Run docformatter

* Run docformatter once again

* Run pre-commit

* Add water level tests

* Black

* make linters happy

* Generalize airhumidifer tests, parametrize water_level tests

* Cleanup set_dry test

* Fix set_dry tests on v1

* Simplify water_level logic

* Convert test_airhumidifer_miot away from TestCase

Co-authored-by: Teemu Rytilahti <tpr@iki.fi>

README.rst

@@ -189,7 +189,7 @@ Home Assistant (custom)
 Other related projects
 ----------------------
 
-This is a list of other projects around the xiaomi ecosystem that you can find interesting.
+This is a list of other projects around the Xiaomi ecosystem that you can find interesting.
 Feel free to submit more related projects.
 
 -  `dustcloud <https://github.com/dgiese/dustcloud>`__ (reverse engineering and rooting xiaomi devices)

miio/airhumidifier.py

@@ -198,12 +198,16 @@ def depth(self) -> Optional[int]:
     def water_level(self) -> Optional[int]:
         """Return current water level in percent.
 
-        If water tank is full, depth is 125.
+        If water tank is full, depth is 120. If water tank is overfilled, depth is 125.
         """
         depth = self.data.get("depth")
-        if depth is not None and depth <= 125:
-            return int(depth / 1.25)
-        return None
+        if depth is None or depth > 125:
+            return None
+
+        if depth < 0:
+            return 0
+
+        return int(min(depth / 1.2, 100))
 
     @property
     def water_tank_detached(self) -> Optional[bool]:

miio/airhumidifier_miot.py

@@ -129,11 +129,17 @@ def target_humidity(self) -> int:
     def water_level(self) -> Optional[int]:
         """Return current water level in percent.
 
-        If water tank is full, depth is 125.
+        If water tank is full, raw water_level value is 120. If water tank is
+        overfilled, raw water_level value is 125.
         """
-        if self.data["water_level"] <= 125:
-            return int(self.data["water_level"] / 1.25)
-        return None
+        water_level = self.data["water_level"]
+        if water_level > 125:
+            return None
+
+        if water_level < 0:
+            return 0
+
+        return int(min(water_level / 1.2, 100))
 
     @property
     def water_tank_detached(self) -> bool: