[Android] Detect if device is not charging properly.

build/android/devil/android/battery_utils_test.py

Index: build/android/devil/android/battery_utils_test.py
diff --git a/build/android/devil/android/battery_utils_test.py b/build/android/devil/android/battery_utils_test.py
index 734b68d1b20f00ec4de17b1b45a7b07a747c6e28..832b8163e0a8ffaf3575d8ffd2e74fcaa37ce25d 100755
--- a/build/android/devil/android/battery_utils_test.py
+++ b/build/android/devil/android/battery_utils_test.py
@@ -244,13 +244,37 @@ class BatteryUtilsGetPowerData(BatteryUtilsTest):
 class BatteryUtilsChargeDevice(BatteryUtilsTest):
 
   @mock.patch('time.sleep', mock.Mock())
-  def testChargeDeviceToLevel(self):
+  def testChargeDeviceToLevel_pass(self):
     with self.assertCalls(
         (self.call.battery.SetCharging(True)),
         (self.call.battery.GetBatteryInfo(), {'level': '50'}),
         (self.call.battery.GetBatteryInfo(), {'level': '100'})):
       self.battery.ChargeDeviceToLevel(95)
 
+  @mock.patch('time.sleep', mock.Mock())
+  def testChargeDeviceToLevel_failureSame(self):
+    with self.assertCalls(
+        (self.call.battery.SetCharging(True)),
+        (self.call.battery.GetBatteryInfo(), {'level': '50'}),
+        (self.call.battery.GetBatteryInfo(), {'level': '50'})):
+      with self.assertRaises(device_errors.DeviceChargingError):
+        old_max = battery_utils._MAX_CHARGE_ERROR
+        battery_utils._MAX_CHARGE_ERROR = 2
+        self.battery.ChargeDeviceToLevel(95)
+        battery_utils._MAX_CHARGE_ERROR = old_max
+
+  @mock.patch('time.sleep', mock.Mock())
+  def testChargeDeviceToLevel_failureDischarge(self):
+    with self.assertCalls(
+        (self.call.battery.SetCharging(True)),
+        (self.call.battery.GetBatteryInfo(), {'level': '50'}),
+        (self.call.battery.GetBatteryInfo(), {'level': '49'})):
+      with self.assertRaises(device_errors.DeviceChargingError):
+        old_max = battery_utils._MAX_CHARGE_ERROR
+        battery_utils._MAX_CHARGE_ERROR = 2
+        self.battery.ChargeDeviceToLevel(95)
+        battery_utils._MAX_CHARGE_ERROR = old_max
+
 
 class BatteryUtilsDischargeDevice(BatteryUtilsTest):