autotest: add a test for in-flight compass learning

Tools/autotest/arduplane.py

@@ -6445,6 +6445,28 @@ def ForceArm(self):
             )
             self.disarm_vehicle()
 
+    def CompassLearnInFlight(self):
+        '''check we can learn compass offsets in flight'''
+        self.context_push()
+        self.set_parameters({
+            "COMPASS_OFS_X": 1100,
+        })
+        self.assert_prearm_failure("Check mag field", other_prearm_failures_fatal=False)
+        self.context_pop()
+        self.wait_ready_to_arm()
+        self.takeoff(30, mode='TAKEOFF')
+        self.assert_parameter_value("COMPASS_OFS_X", 20, epsilon=30)
+        old_compass_ofs_x = self.get_parameter('COMPASS_OFS_X')
+        self.set_parameters({
+            "COMPASS_OFS_X": 1100,
+        })
+        self.set_parameter("COMPASS_LEARN", 3)  # 3 is in-flight learning
+        self.wait_parameter_value("COMPASS_LEARN", 0)
+        self.assert_parameter_value("COMPASS_OFS_X", old_compass_ofs_x, epsilon=30)
+        self.fly_home_land_and_disarm()
+        self.reboot_sitl()
+        self.assert_parameter_value("COMPASS_OFS_X", old_compass_ofs_x, epsilon=30)
+
     def _MAV_CMD_EXTERNAL_WIND_ESTIMATE(self, command):
         self.reboot_sitl()
 
@@ -6839,6 +6861,7 @@ def tests1b(self):
             self.MAV_CMD_DO_LAND_START,
             self.MAV_CMD_NAV_ALTITUDE_WAIT,
             self.InteractTest,
+            self.CompassLearnInFlight,
             self.MAV_CMD_MISSION_START,
             self.TerrainRally,
             self.MAV_CMD_NAV_LOITER_UNLIM,