diff --git a/aircox_streamer/controllers/monitor.py b/aircox_streamer/controllers/monitor.py
index 0e8f46a..cc24c33 100644
--- a/aircox_streamer/controllers/monitor.py
+++ b/aircox_streamer/controllers/monitor.py
@@ -223,9 +223,8 @@ class Monitor:
             or dealer.remaining < self.delay.total_seconds()
         ):
             self.start_diff(dealer, diff)
-
         # cancel
-        if diff.start < now - self.cancel_timeout:
+        elif diff.start < now - self.cancel_timeout:
             self.cancel_diff(dealer, diff)
 
     def log(self, source, **kwargs):
diff --git a/aircox_streamer/tests/conftest.py b/aircox_streamer/tests/conftest.py
index b38e766..2778272 100644
--- a/aircox_streamer/tests/conftest.py
+++ b/aircox_streamer/tests/conftest.py
@@ -318,7 +318,8 @@ def streamer(station, station_ports):
     streamer.sources = [
         FakePlaylist(i, uri=f"source-{i}") for i in range(0, 3)
     ]
-    streamer.sources.append(FakeQueueSource(len(streamer.sources)))
+    streamer.dealer = FakeQueueSource(len(streamer.sources))
+    streamer.sources.append(streamer.dealer)
     return streamer
 
 
diff --git a/aircox_streamer/tests/test_controllers_monitor.py b/aircox_streamer/tests/test_controllers_monitor.py
index 6390265..7202b8f 100644
--- a/aircox_streamer/tests/test_controllers_monitor.py
+++ b/aircox_streamer/tests/test_controllers_monitor.py
@@ -20,13 +20,13 @@ def monitor(streamer):
 
 
 @pytest.fixture
-def diffusion(program, episode):
+def diffusion(program, episode, sound):
     return baker.make(
         models.Diffusion,
         program=program,
         episode=episode,
-        start=tz.now() - tz.timedelta(minutes=10),
-        end=tz.now() + tz.timedelta(minutes=30),
+        start=tz.now() - tz.timedelta(minutes=2),
+        end=tz.now() + tz.timedelta(minutes=4),
         schedule=None,
         type=models.Diffusion.TYPE_ON_AIR,
     )
@@ -64,8 +64,10 @@ def log(station, source, sound):
 
 class TestMonitor:
     @pytest.mark.django_db(transaction=True)
-    def test_last_diff_start(self, monitor):
-        pass
+    def test_last_diff_start(self, monitor, diffusion, log):
+        log.diffusion = diffusion
+        log.save()
+        assert monitor.last_diff_start == log
 
     @pytest.mark.django_db(transaction=True)
     def test___init__(self, monitor):
@@ -188,8 +190,92 @@ class TestMonitor:
         monitor.trace_tracks(log)
 
     @pytest.mark.django_db(transaction=True)
-    def test_handle_diffusions(self, monitor):
-        pass
+    def test_handle_diffusions(self, monitor, streamer, diffusion, sound):
+        interface(
+            monitor,
+            {
+                "start_diff": None,
+                "cancel_diff": None,
+            },
+        )
+        streamer.dealer.queue = [1]
+        streamer.dealer.rid = None
+        streamer.dealer.remaining = monitor.delay.total_seconds() - 10
+
+        monitor.handle_diffusions()
+        assert monitor.calls["start_diff"] == (
+            (streamer.dealer, diffusion),
+            {},
+        )
+        assert not monitor.calls["cancel_diff"]
+
+    @pytest.mark.django_db(transaction=True)
+    def test_handle_diffusions_returns_on_diff(
+        self, monitor, streamer, diffusion, log
+    ):
+        interface(
+            monitor,
+            {
+                "start_diff": None,
+                "cancel_diff": None,
+            },
+        )
+        streamer.dealer.queue = [1]
+        streamer.dealer.rid = None
+        streamer.dealer.remaining = monitor.delay.total_seconds() - 10
+        diffusion.start = tz.now() - tz.timedelta(minutes=30)
+        diffusion.end = tz.now() - tz.timedelta(minutes=20)
+        diffusion.save()
+
+        monitor.handle_diffusions()
+        assert not monitor.calls["start_diff"]
+        assert not monitor.calls["cancel_diff"]
+
+    @pytest.mark.django_db(transaction=True)
+    def test_handle_diffusions_returns_on_diff_log_exists(
+        self, monitor, streamer, diffusion, log
+    ):
+        interface(
+            monitor,
+            {
+                "start_diff": None,
+                "cancel_diff": None,
+            },
+        )
+        streamer.dealer.queue = [1]
+        streamer.dealer.rid = None
+        streamer.dealer.remaining = monitor.delay.total_seconds() - 10
+        log.diffusion = diffusion
+        log.save()
+
+        monitor.handle_diffusions()
+        assert not monitor.calls["start_diff"]
+        assert not monitor.calls["cancel_diff"]
+
+    @pytest.mark.django_db(transaction=True)
+    def test_handle_diffusions_cancel_diff(self, monitor, streamer, diffusion):
+        interface(
+            monitor,
+            {
+                "start_diff": None,
+                "cancel_diff": None,
+            },
+        )
+        streamer.dealer.queue = None
+        streamer.dealer.rid = "13"
+        streamer.dealer.remaining = monitor.delay.total_seconds() + 10
+        diffusion.start = (
+            tz.now() - monitor.cancel_timeout - tz.timedelta(seconds=30)
+        )
+        diffusion.end = tz.now() + tz.timedelta(minutes=30)
+        diffusion.save()
+
+        monitor.handle_diffusions()
+        assert not monitor.calls["start_diff"]
+        assert monitor.calls["cancel_diff"] == (
+            (streamer.dealer, diffusion),
+            {},
+        )
 
     @pytest.mark.django_db(transaction=True)
     def test_log(self, monitor, source):