autotest: disable terrain during frsky passthrough test

If terrain isn't available then our expected statustext gets blatted with one which RCTelemetry library emits

Tools/autotest/arduplane.py

@@ -3897,9 +3897,13 @@ function'''
              "Test FrSky SPort mode",
              self.test_frsky_sport),
 
-            ("FRSkyPassThrough",
-             "Test FrSky PassThrough serial output",
-             self.test_frsky_passthrough),
+            ("FRSkyPassThroughStatustext",
+             "Test FrSky PassThrough serial output - statustext",
+             self.FRSkyPassThroughStatustext),
+
+            ("FRSkyPassThroughSensorIDs",
+             "Test FrSky PassThrough serial output - sensor ids",
+             self.FRSkyPassThroughSensorIDs),
 
             ("FRSkyMAVlite",
              "Test FrSky MAVlite serial output",

Tools/autotest/common.py

@@ -11027,9 +11027,16 @@ switch value'''
                     self.progress("  Fulfilled")
                     del wants[want]
 
-    def test_frsky_passthrough(self):
-        self.set_parameter("SERIAL5_PROTOCOL", 10) # serial5 is FRSky passthrough
-        self.set_parameter("RPM1_TYPE", 10) # enable RPM output
+    def FRSkyPassThroughStatustext(self):
+        '''test FRSKy protocol's telem-passthrough functionality'''
+        # we disable terrain here as RCTelemetry can queue a lot of
+        # statustexts if terrain tiles aren't available which can
+        # happen on the autotest server.
+        self.set_parameters({
+            "SERIAL5_PROTOCOL": 10, # serial5 is FRSky passthrough
+            "RPM1_TYPE": 10, # enable RPM output
+            "TERRAIN_ENABLE": 0,
+        })
         self.customise_SITL_commandline([
             "--uartF=tcp:6735" # serial5 spews to localhost:6735
         ])
@@ -11047,6 +11054,7 @@ switch value'''
         tstart = self.get_sim_time()
         old_data = None
         text = ""
+
         self.context_collect('STATUSTEXT')
         self.run_cmd(mavutil.mavlink.MAV_CMD_PREFLIGHT_CALIBRATION,
                      0, # p1
@@ -11112,12 +11120,22 @@ switch value'''
                                 raise NotAchievedException("Incorrect severity; want=%u got=%u" % (want_sev, severity))
                             self.progress("Got statustext (%s)" % received_text)
                             break
-        self.context_stop_collecting('STATUSTEXT')
+
+    def FRSkyPassThroughSensorIDs(self):
+        '''test FRSKy protocol's telem-passthrough functionality (sensor IDs)'''
+        self.set_parameters({
+            "SERIAL5_PROTOCOL": 10, # serial5 is FRSky passthrough
+            "RPM1_TYPE": 10, # enable RPM output
+        })
+        self.customise_SITL_commandline([
+            "--uartF=tcp:6735" # serial5 spews to localhost:6735
+        ])
+        frsky = FRSkyPassThrough(("127.0.0.1", 6735),
+                                 get_time=self.get_sim_time_cached)
 
         self.wait_ready_to_arm()
 
         # we need to start the engine to get some RPM readings, we do it for plane only
-        self.drain_mav()
         # anything with a lambda in here needs a proper test written.
         # This, at least makes sure we're getting some of each
         # message.  These are ordered according to the wfq scheduler