autotest: add battery_charge_state ok & low tests

Tools/autotest/arducopter.py

@@ -934,15 +934,21 @@ class AutoTestCopter(AutoTest):
         # no action taken.
         self.start_subtest("Batt failsafe disabled test")
         self.takeoffAndMoveAway()
+        m = self.mav.recv_match(type='BATTERY_STATUS', blocking=True, timeout=1)
+        if m.charge_state != mavutil.mavlink.MAV_BATTERY_CHARGE_STATE_OK:
+            raise NotAchievedException("Expected state ok")
         self.set_parameter('SIM_BATT_VOLTAGE', 11.4)
         self.wait_statustext("Battery 1 is low", timeout=60)
+        m = self.mav.recv_match(type='BATTERY_STATUS', blocking=True, timeout=1)
+        if m.charge_state != mavutil.mavlink.MAV_BATTERY_CHARGE_STATE_LOW:
+            raise NotAchievedException("Expected state low")
         self.delay_sim_time(5)
         self.wait_mode("ALT_HOLD")
         self.set_parameter('SIM_BATT_VOLTAGE', 10.0)
         self.wait_statustext("Battery 1 is critical", timeout=60)
         m = self.mav.recv_match(type='BATTERY_STATUS', blocking=True, timeout=1)
         if m.charge_state != mavutil.mavlink.MAV_BATTERY_CHARGE_STATE_CRITICAL:
-            raise NotAchievedException("Execpted state critical")
+            raise NotAchievedException("Expected state critical")
         self.delay_sim_time(5)
         self.wait_mode("ALT_HOLD")
         self.change_mode("RTL")