diff --git a/test/towerops/on_call/escalation_test.exs b/test/towerops/on_call/escalation_test.exs
index 0f2876f7..c085e06a 100644
--- a/test/towerops/on_call/escalation_test.exs
+++ b/test/towerops/on_call/escalation_test.exs
@@ -72,6 +72,31 @@ defmodule Towerops.OnCall.EscalationTest do
 
       assert {:error, :no_policy} = Escalation.start_escalation(alert, nil)
     end
+
+    test "returns :no_policy when policy_id is empty string", ctx do
+      {:ok, alert} =
+        Alerts.create_alert(%{
+          alert_type: "device_down",
+          device_id: ctx.device.id,
+          triggered_at: DateTime.utc_now(),
+          message: "Device is down"
+        })
+
+      assert {:error, :no_policy} = Escalation.start_escalation(alert, "")
+    end
+
+    test "returns :no_policy when policy id refers to a non-existent record", ctx do
+      {:ok, alert} =
+        Alerts.create_alert(%{
+          alert_type: "device_down",
+          device_id: ctx.device.id,
+          triggered_at: DateTime.utc_now(),
+          message: "Device is down"
+        })
+
+      assert {:error, :no_policy} =
+               Escalation.start_escalation(alert, Ecto.UUID.generate())
+    end
   end
 
   describe "acknowledge_incident/2" do
diff --git a/test/towerops/snmp/profiles/vendors/airfiber_test.exs b/test/towerops/snmp/profiles/vendors/airfiber_test.exs
index 85e972dd..a10862d3 100644
--- a/test/towerops/snmp/profiles/vendors/airfiber_test.exs
+++ b/test/towerops/snmp/profiles/vendors/airfiber_test.exs
@@ -170,4 +170,24 @@ defmodule Towerops.Snmp.Profiles.Vendors.AirfiberTest do
       assert sensors == []
     end
   end
+
+  describe "detect_version/1" do
+    test "returns the version string when SNMP responds" do
+      expect(SnmpMock, :get, fn _, "1.3.6.1.4.1.41112.1.3.2.1.40.1", _opts ->
+        {:ok, "v4.1.0"}
+      end)
+
+      assert "v4.1.0" == Airfiber.detect_version(@client_opts)
+    end
+
+    test "returns nil when SNMP returns an empty string" do
+      expect(SnmpMock, :get, fn _, _, _ -> {:ok, ""} end)
+      assert nil == Airfiber.detect_version(@client_opts)
+    end
+
+    test "returns nil on timeout" do
+      expect(SnmpMock, :get, fn _, _, _ -> {:error, :timeout} end)
+      assert nil == Airfiber.detect_version(@client_opts)
+    end
+  end
 end