autotest: add new blending test

Tools/autotest/arducopter.py

@@ -8752,7 +8752,7 @@ def test_replay_optical_flow_bit(self):
         print("log difference: %s" % str(log_difference))
         return log_difference[0]
 
-    def GPSBlending(self):
+    def GPSBlendingLog(self):
         '''Test GPS Blending'''
         '''ensure we get dataflash log messages for blended instance'''
 
@@ -8827,6 +8827,67 @@ def GPSBlending(self):
         if ex is not None:
             raise ex
 
+    def GPSBlending(self):
+        '''Test GPS Blending'''
+        '''ensure we get dataflash log messages for blended instance'''
+
+        self.context_push()
+
+        # configure:
+        self.set_parameters({
+            "WP_YAW_BEHAVIOR": 0,  # do not yaw
+            "GPS2_TYPE": 1,
+            "SIM_GPS2_TYPE": 1,
+            "SIM_GPS2_DISABLE": 0,
+            "SIM_GPS_POS_X": 1.0,
+            "SIM_GPS_POS_Y": -1.0,
+            "SIM_GPS2_POS_X": -1.0,
+            "SIM_GPS2_POS_Y": 1.0,
+            "GPS_AUTO_SWITCH": 2,
+        })
+        self.reboot_sitl()
+
+        alt = 10
+        self.takeoff(alt, mode='GUIDED')
+        self.fly_guided_move_local(30, 0, alt)
+        self.fly_guided_move_local(30, 30, alt)
+        self.fly_guided_move_local(0, 30, alt)
+        self.fly_guided_move_local(0, 0, alt)
+        self.change_mode('LAND')
+
+        current_log_file = self.dfreader_for_current_onboard_log()
+
+        self.wait_disarmed()
+
+        # ensure that the blended solution is always about half-way
+        # between the two GPSs:
+        current_ts = None
+        while True:
+            m = current_log_file.recv_match(type='GPS')
+            if m is None:
+                break
+            if current_ts is None:
+                if m.I != 0:  # noqa
+                    continue
+                current_ts = m.TimeUS
+                measurements = {}
+            if m.TimeUS != current_ts:
+                current_ts = None
+                continue
+            measurements[m.I] = (m.Lat, m.Lng)
+            if len(measurements) == 3:
+                # check lat:
+                for n in 0, 1:
+                    expected_blended = (measurements[0][n] + measurements[1][n])/2
+                    epsilon = 0.0000002
+                    error = abs(measurements[2][n] - expected_blended)
+                    if error > epsilon:
+                        raise NotAchievedException("Blended diverged")
+                current_ts = None
+
+        self.context_pop()
+        self.reboot_sitl()
+
     def Callisto(self):
         '''Test Callisto'''
         self.customise_SITL_commandline(
@@ -10936,6 +10997,7 @@ def tests2b(self):  # this block currently around 9.5mins here
             self.RTL_TO_RALLY,
             self.FlyEachFrame,
             self.GPSBlending,
+            self.GPSBlendingLog,
             self.DataFlash,
             Test(self.DataFlashErase, attempts=8),
             self.Callisto,