Add a test for disconnecting a client in sensor_update

See NGC-1440.

src/aiokatcp/sensor.py

@@ -1,4 +1,4 @@
-# Copyright 2017, 2019, 2022 National Research Foundation (SARAO)
+# Copyright 2017, 2019, 2022, 2024 National Research Foundation (SARAO)
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are met:
@@ -226,9 +226,10 @@ def notify(self, reading: Reading[_T], old_reading: Reading[_T]) -> None:
         Users should not usually call this directly. It is called automatically
         by :meth:`set_value`.
         """
-        for classic_observer in self._classic_observers:
+        # list() is to avoid errors if the set is modified during iteration.
+        for classic_observer in list(self._classic_observers):
             classic_observer(self, reading)
-        for delta_observer in self._delta_observers:
+        for delta_observer in list(self._delta_observers):
             delta_observer(self, reading, old_reading=old_reading)
 
     def set_value(

tests/test_server.py

@@ -75,6 +75,8 @@ def __init__(self):
         self.sensors.add(sensor)
         sensor = Sensor(float, "float-sensor", "generic float sensor")
         self.sensors.add(sensor)
+        sensor = Sensor(bytes, "str-sensor", "generic string sensor")
+        self.sensors.add(sensor)
         sensor = Sensor(
             int,
             "auto-override",
@@ -333,7 +335,8 @@ async def test_sensor_list_no_filter(
             rb"#sensor-list[4] counter-queries number\_of\_?counter\_queries \@ integer" + b"\n",
             rb"#sensor-list[4] float-sensor generic\_float\_sensor \@ float" + b"\n",
             rb"#sensor-list[4] foo nonsense \@ discrete first-value second-value" + b"\n",
-            b"!sensor-list[4] ok 4\n",
+            rb"#sensor-list[4] str-sensor generic\_string\_sensor \@ string" + b"\n",
+            b"!sensor-list[4] ok 5\n",
         ],
     )
 
@@ -368,7 +371,8 @@ async def test_sensor_list_regex_filter(
             rb"#sensor-list[6] counter-queries number\_of\_?counter\_queries \@ integer" + b"\n",
             rb"#sensor-list[6] float-sensor generic\_float\_sensor \@ float" + b"\n",
             rb"#sensor-list[6] foo nonsense \@ discrete first-value second-value" + b"\n",
-            b"!sensor-list[6] ok 3\n",
+            rb"#sensor-list[6] str-sensor generic\_string\_sensor \@ string" + b"\n",
+            b"!sensor-list[6] ok 4\n",
         ],
     )
 
@@ -398,7 +402,8 @@ async def test_sensor_value(
             b"#sensor-value[9] 123456789.0 1 counter-queries nominal 0\n",
             b"#sensor-value[9] 123456789.0 1 float-sensor unknown 0.0\n",
             b"#sensor-value[9] 123456789.0 1 foo unknown first-value\n",
-            b"!sensor-value[9] ok 4\n",
+            b"#sensor-value[9] 123456789.0 1 str-sensor unknown \\@\n",
+            b"!sensor-value[9] ok 5\n",
         ],
     )
 
@@ -637,6 +642,24 @@ async def test_slow_client(server: DummyServer, reader: asyncio.StreamReader) ->
     assert len(server._connections) == 0
 
 
+async def test_slow_client_sensor(
+    server: DummyServer, reader: asyncio.StreamReader, writer: asyncio.StreamWriter
+) -> None:
+    server.max_backlog = 32768
+    big_str = b"x" * 200000
+    writer.write(b"?sensor-sampling str-sensor auto\n")
+    await check_reply(
+        reader,
+        [
+            re.compile(rb"^#sensor-status [0-9.]+ 1 str-sensor unknown \\@"),
+            b"!sensor-sampling ok str-sensor auto\n",
+        ],
+    )
+    assert len(server._connections) == 1
+    server.sensors["str-sensor"].value = big_str
+    assert len(server._connections) == 0
+
+
 async def test_sensor_sampling_invalid(
     reader: asyncio.StreamReader, writer: asyncio.StreamWriter
 ) -> None: