autotest: add a test to ensure we get voltage from generator in battery_status message

Tools/autotest/arducopter.py

@@ -4822,6 +4822,7 @@ class AutoTestCopter(AutoTest):
         self.set_parameter("SIM_RICH_CTRL", 8)
         self.set_parameter("RC9_OPTION", 85)
         self.set_parameter("LOG_DISARMED", 1)
+        self.set_parameter("BATT2_MONITOR", 17)
         self.set_rc(9, 1000) # remember this is a switch position - stop
         self.customise_SITL_commandline(["--uartF=sim:richenpower"])
         self.mavproxy.expect("requested state is not RUN")
@@ -4854,6 +4855,19 @@ class AutoTestCopter(AutoTest):
 
         self.wait_generator_speed_and_state(8000, 30000, mavutil.mavlink.MAV_GENERATOR_STATUS_FLAG_GENERATING)
 
+        bs = self.mav.recv_match(
+            type="BATTERY_STATUS",
+            condition="BATTERY_STATUS.id==1",  # id is zero-indexed
+            timeout=1,
+            blocking=True
+        )
+        if bs is None:
+            raise NotAchievedException("Did not receive BATTERY_STATUS")
+        self.progress("Received battery status: %s" % str(bs))
+        want_bs_volt = 50000
+        if bs.voltages[0] != want_bs_volt:
+            raise NotAchievedException("Battery voltage not as expected (want=%f) got=(%f)" % (want_bs_volt, bs.voltages[0],))
+
         self.progress("Moving *back* to idle")
         self.set_rc(9, 1500) # remember this is a switch position - idle
         self.wait_generator_speed_and_state(3000, 10000, mavutil.mavlink.MAV_GENERATOR_STATUS_FLAG_IDLE)