Tools: test use Location::AltFrame for guided_state.target_alt_frame

Tools/autotest/arduplane.py

@@ -5533,6 +5533,7 @@ def RunMissionScript(self):
 
     def MAV_CMD_GUIDED_CHANGE_ALTITUDE(self):
         '''test handling of MAV_CMD_GUIDED_CHANGE_ALTITUDE'''
+        self.start_subtest("set home relative altitude")
         self.takeoff(30, relative=True)
         self.change_mode('GUIDED')
         for alt in 50, 70:
@@ -5544,6 +5545,7 @@ def MAV_CMD_GUIDED_CHANGE_ALTITUDE(self):
             self.wait_altitude(alt-1, alt+1, timeout=30, relative=True)
 
         # test for #24535
+        self.start_subtest("switch to loiter and resume guided maintains home relative altitude")
         self.change_mode('LOITER')
         self.delay_sim_time(5)
         self.change_mode('GUIDED')
@@ -5554,6 +5556,55 @@ def MAV_CMD_GUIDED_CHANGE_ALTITUDE(self):
             timeout=30,
             relative=True,
         )
+        # test that this works if switching between RELATIVE (HOME) and GLOBAL(AMSL)
+        self.start_subtest("set global/AMSL altitude, switch to loiter and resume guided")
+        alt = 625
+        self.run_cmd_int(
+            mavutil.mavlink.MAV_CMD_GUIDED_CHANGE_ALTITUDE,
+            p7=alt,
+            frame=mavutil.mavlink.MAV_FRAME_GLOBAL,
+        )
+        self.wait_altitude(alt-3, alt+3, timeout=30, relative=False)
+        self.change_mode('LOITER')
+        self.delay_sim_time(5)
+        self.change_mode('GUIDED')
+        self.wait_altitude(
+            alt-5,  # NOTE: reuse of alt from above CHANGE_ALTITUDE
+            alt+5,
+            minimum_duration=10,
+            timeout=30,
+            relative=False,
+        )
+        # test that this works if switching between RELATIVE (HOME) and terrain
+        self.start_subtest("set terrain altitude, switch to loiter and resume guided")
+        self.change_mode('GUIDED')
+        alt = 100
+        self.run_cmd_int(
+            mavutil.mavlink.MAV_CMD_GUIDED_CHANGE_ALTITUDE,
+            p7=alt,
+            frame=mavutil.mavlink.MAV_FRAME_GLOBAL_TERRAIN_ALT,
+        )
+        self.wait_altitude(
+            alt-5,  # NOTE: reuse of alt from abovE
+            alt+5,  # use a 5m buffer as the plane needs to go up and down a bit to maintain terrain distance
+            minimum_duration=10,
+            timeout=30,
+            relative=False,
+            altitude_source="TERRAIN_REPORT.current_height"
+        )
+        self.change_mode('LOITER')
+        self.delay_sim_time(5)
+        self.change_mode('GUIDED')
+        self.wait_altitude(
+            alt-5,  # NOTE: reuse of alt from abovE
+            alt+5,  # use a 5m buffer as the plane needs to go up and down a bit to maintain terrain distance
+            minimum_duration=10,
+            timeout=30,
+            relative=False,
+            altitude_source="TERRAIN_REPORT.current_height"
+        )
+
+        self.delay_sim_time(5)
         self.fly_home_land_and_disarm()
 
     def _MAV_CMD_PREFLIGHT_CALIBRATION(self, command):

Tools/autotest/vehicle_test_suite.py

@@ -7176,6 +7176,10 @@ def get_altitude(self, relative=False, timeout=30, altitude_source=None):
                 altitude_source = "GLOBAL_POSITION_INT.relative_alt"
             else:
                 altitude_source = "GLOBAL_POSITION_INT.alt"
+        if altitude_source == "TERRAIN_REPORT.current_height":
+            terrain = self.assert_receive_message('TERRAIN_REPORT')
+            return terrain.current_height
+
         (msg, field) = altitude_source.split('.')
         msg = self.poll_message(msg, quiet=True)
         divisor = 1000.0  # mm is pretty common in mavlink