autotest: Enabled/edited old test and added new test on home alt reset

Tools/autotest/arduplane.py

@@ -6185,14 +6185,18 @@ def GPSPreArms(self):
     def SetHomeAltChange(self):
         '''check modes retain altitude when home alt changed'''
         for mode in 'FBWB', 'CRUISE', 'LOITER':
+            self.set_rc(3, 1000)
             self.wait_ready_to_arm()
             home = self.home_position_as_mav_location()
-            self.takeoff(20)
-            higher_home = home
+            target_alt = 20
+            self.takeoff(target_alt, mode="TAKEOFF")
+            self.delay_sim_time(20)  # Give some time to altitude to stabilize.
+            self.set_rc(3, 1500)
+            self.change_mode(mode)
+            higher_home = copy.copy(home)
             higher_home.alt += 40
             self.set_home(higher_home)
-            self.change_mode(mode)
-            self.wait_altitude(15, 25, relative=True, minimum_duration=10)
+            self.wait_altitude(home.alt+target_alt-5, home.alt+target_alt+5, relative=False, minimum_duration=10, timeout=11)
             self.disarm_vehicle(force=True)
             self.reboot_sitl()
 
@@ -6228,6 +6232,23 @@ def SetHomeAltChange2(self):
         self.disarm_vehicle(force=True)
         self.reboot_sitl()
 
+    def SetHomeAltChange3(self):
+        '''same as SetHomeAltChange, but the home alt change occurs during TECS operation'''
+        self.wait_ready_to_arm()
+        home = self.home_position_as_mav_location()
+        target_alt = 20
+        self.takeoff(target_alt, mode="TAKEOFF")
+        self.change_mode("LOITER")
+        self.delay_sim_time(20) # Let the plane settle.
+
+        higher_home = copy.copy(home)
+        higher_home.alt += 40
+        self.set_home(higher_home)
+        self.wait_altitude(home.alt+target_alt-5, home.alt+target_alt+5, relative=False, minimum_duration=10, timeout=10.1)
+
+        self.disarm_vehicle(force=True)
+        self.reboot_sitl()
+
     def ForceArm(self):
         '''check force-arming functionality'''
         self.set_parameter("SIM_GPS1_ENABLE", 0)
@@ -6497,6 +6518,7 @@ def tests1b(self):
             self.GPSPreArms,
             self.SetHomeAltChange,
             self.SetHomeAltChange2,
+            self.SetHomeAltChange3,
             self.ForceArm,
             self.MAV_CMD_EXTERNAL_WIND_ESTIMATE,
             self.GliderPullup,
@@ -6508,7 +6530,6 @@ def disabled_tests(self):
             "LandingDrift": "Flapping test. See https://github.com/ArduPilot/ardupilot/issues/20054",
             "InteractTest": "requires user interaction",
             "ClimbThrottleSaturation": "requires https://github.com/ArduPilot/ardupilot/pull/27106 to pass",
-            "SetHomeAltChange": "https://github.com/ArduPilot/ardupilot/issues/5672",
         }