add test case with long list of topics

Author: vladak

tests/test_unsubscribe.py

@@ -24,8 +24,10 @@ def handle_unsubscribe(client, user_data, topic, pid):
 
 
 # The MQTT packet contents below were captured using Mosquitto client+server.
-# These are verbatim, except message ID that was changed from 2 to 1 since in the real world
-# capture the UNSUBSCRIBE packet followed the SUBSCRIBE packet.
+# These are all verbatim, except:
+#   - message ID that was changed from 2 to 1 since in the real world
+#     the UNSUBSCRIBE packet followed the SUBSCRIBE packet.
+#   - the long list topics is sent as individual UNSUBSCRIBE packets by Mosquitto
 testdata = [
     # short topic with remaining length encoded as single byte
     (
@@ -67,11 +69,37 @@ def handle_unsubscribe(client, user_data, topic, pid):
             + [0x6F] * 257
         ),
     ),
+    # use list of topics for more coverage. If the range was (1, 10000), that would be
+    # long enough to use 3 bytes for remaining length, however that would make the test
+    # run for many minutes even on modern systems, so 1000 is used instead.
+    # This results in 2 bytes for the remaining length.
+    (
+        [f"foo/bar{x:04}" for x in range(1, 1000)],
+        bytearray([0xB0, 0x02, 0x00, 0x01]),
+        bytearray(
+            [
+                0xA2,  # fixed header
+                0xBD,  # remaining length
+                0x65,
+                0x00,  # message ID
+                0x01,
+            ]
+            + sum(
+                [
+                    [0x00, 0x0B] + list(f"foo/bar{x:04}".encode("ascii"))
+                    for x in range(1, 1000)
+                ],
+                [],
+            )
+        ),
+    ),
 ]
 
 
 @pytest.mark.parametrize(
-    "topic,to_send,exp_recv", testdata, ids=["short_topic", "long_topic"]
+    "topic,to_send,exp_recv",
+    testdata,
+    ids=["short_topic", "long_topic", "topic_list_long"],
 )
 def test_unsubscribe(topic, to_send, exp_recv) -> None:
     """
@@ -107,11 +135,19 @@ def test_unsubscribe(topic, to_send, exp_recv) -> None:
     mqtt_client.logger = logger
 
     # pylint: disable=protected-access
-    mqtt_client._subscribed_topics = [topic]
+    if isinstance(topic, str):
+        mqtt_client._subscribed_topics = [topic]
+    elif isinstance(topic, list):
+        mqtt_client._subscribed_topics = topic
 
     # pylint: disable=logging-fstring-interpolation
     logger.info(f"unsubscribing from {topic}")
     mqtt_client.unsubscribe(topic)
 
-    assert topic in unsubscribed_topics
+    if isinstance(topic, str):
+        assert topic in unsubscribed_topics
+    elif isinstance(topic, list):
+        for topic_name in topic:
+            assert topic_name in unsubscribed_topics
     assert mocket.sent == exp_recv
+    assert len(mocket._to_send) == 0