diff --git a/tests/test_client.py b/tests/test_client.py
index d6457fe7..145f911c 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -1,19 +1,21 @@
+import threading
 import time
 import unicodedata
 
 import paho.mqtt.client as client
 import pytest
+from paho.mqtt.enums import MQTTErrorCode, MQTTProtocolVersion
 from paho.mqtt.reasoncodes import ReasonCodes
 
 import tests.paho_test as paho_test
 
 # Import test fixture
-from tests.testsupport.broker import fake_broker  # noqa: F401
+from tests.testsupport.broker import FakeBroker, fake_broker  # noqa: F401
 
 
 @pytest.mark.parametrize("proto_ver", [
-    (client.MQTTv31),
-    (client.MQTTv311),
+    (MQTTProtocolVersion.MQTTv31),
+    (MQTTProtocolVersion.MQTTv311),
 ])
 class Test_connect:
     """
@@ -100,7 +102,7 @@ class Test_connect_v5:
 
     def test_01_broker_no_support(self, fake_broker):
         mqttc = client.Client(
-            "01-broker-no-support", protocol=client.MQTTv5)
+            "01-broker-no-support", protocol=MQTTProtocolVersion.MQTTv5)
 
         def on_connect(mqttc, obj, flags, reason, properties):
             assert reason == 132
@@ -137,6 +139,116 @@ def on_connect(mqttc, obj, flags, reason, properties):
             mqttc.loop_stop()
 
 
+class TestConnectionLost:
+    def test_with_loop_start(self, fake_broker: FakeBroker):
+        mqttc = client.Client(
+            "test_with_loop_start",
+            protocol=MQTTProtocolVersion.MQTTv311,
+            reconnect_on_failure=False,
+        )
+
+        on_connect_reached = threading.Event()
+        on_disconnect_reached = threading.Event()
+
+
+        def on_connect(mqttc, obj, flags, rc):
+            assert rc == 0
+            on_connect_reached.set()
+
+        def on_disconnect(*args):
+            on_disconnect_reached.set()
+
+        mqttc.on_connect = on_connect
+        mqttc.on_disconnect = on_disconnect
+
+        mqttc.connect_async("localhost", fake_broker.port)
+        mqttc.loop_start()
+
+        try:
+            fake_broker.start()
+
+            connect_packet = paho_test.gen_connect(
+                "test_with_loop_start", keepalive=60,
+                proto_ver=MQTTProtocolVersion.MQTTv311)
+            packet_in = fake_broker.receive_packet(1000)
+            assert packet_in  # Check connection was not closed
+            assert packet_in == connect_packet
+
+            connack_packet = paho_test.gen_connack(rc=0)
+            count = fake_broker.send_packet(connack_packet)
+            assert count  # Check connection was not closed
+            assert count == len(connack_packet)
+
+            assert on_connect_reached.wait(1)
+            assert mqttc.is_connected()
+
+            fake_broker.finish()
+
+            assert on_disconnect_reached.wait(1)
+            assert not mqttc.is_connected()
+
+        finally:
+            mqttc.loop_stop()
+
+    def test_with_loop(self, fake_broker: FakeBroker):
+        mqttc = client.Client(
+            "test_with_loop",
+            clean_session=True,
+        )
+
+        on_connect_reached = threading.Event()
+        on_disconnect_reached = threading.Event()
+
+
+        def on_connect(mqttc, obj, flags, rc):
+            assert rc == 0
+            on_connect_reached.set()
+
+        def on_disconnect(*args):
+            on_disconnect_reached.set()
+
+        mqttc.on_connect = on_connect
+        mqttc.on_disconnect = on_disconnect
+
+
+        try:
+            mqttc.connect("localhost", fake_broker.port)
+
+            fake_broker.start()
+
+            # not yet connected, packet are not yet processed by loop()
+            assert not mqttc.is_connected()
+
+            # connect packet is sent during connect() call
+            connect_packet = paho_test.gen_connect(
+                "test_with_loop", keepalive=60,
+                proto_ver=MQTTProtocolVersion.MQTTv311)
+            packet_in = fake_broker.receive_packet(1000)
+            assert packet_in  # Check connection was not closed
+            assert packet_in == connect_packet
+
+            connack_packet = paho_test.gen_connack(rc=0)
+            count = fake_broker.send_packet(connack_packet)
+            assert count  # Check connection was not closed
+            assert count == len(connack_packet)
+
+            # call loop() to process the connack packet
+            assert mqttc.loop(timeout=1) == MQTTErrorCode.MQTT_ERR_SUCCESS
+
+            assert on_connect_reached.wait(1)
+            assert mqttc.is_connected()
+
+            fake_broker.finish()
+
+            # call loop() to detect the connection lost
+            assert mqttc.loop(timeout=1) == MQTTErrorCode.MQTT_ERR_CONN_LOST
+
+            assert on_disconnect_reached.wait(1)
+            assert not mqttc.is_connected()
+
+        finally:
+            mqttc.loop_stop()
+
 class TestPublishBroker2Client:
 
     def test_invalid_utf8_topic(self, fake_broker):