diff --git a/test/towerops/workers/discovery_worker_test.exs b/test/towerops/workers/discovery_worker_test.exs
new file mode 100644
index 00000000..5dcaf071
--- /dev/null
+++ b/test/towerops/workers/discovery_worker_test.exs
@@ -0,0 +1,130 @@
+defmodule Towerops.Workers.DiscoveryWorkerTest do
+  use Towerops.DataCase, async: true
+
+  import Mox
+  import Towerops.AccountsFixtures
+
+  alias Towerops.Snmp
+  alias Towerops.Snmp.SnmpMock
+  alias Towerops.Workers.DiscoveryWorker
+
+  setup :verify_on_exit!
+
+  describe "perform/1" do
+    setup do
+      user = user_fixture()
+      {:ok, organization} = Towerops.Organizations.create_organization(%{name: "Test Org"}, user.id)
+
+      {:ok, site} =
+        Towerops.Sites.create_site(%{
+          name: "Test Site",
+          organization_id: organization.id
+        })
+
+      {:ok, device} =
+        Towerops.Devices.create_device(%{
+          name: "Test Device",
+          ip_address: "192.168.1.1",
+          snmp_enabled: true,
+          snmp_version: "2c",
+          snmp_community: "public",
+          snmp_port: 161,
+          site_id: site.id
+        })
+
+      {:ok, device: device, org: organization}
+    end
+
+    test "successfully discovers a device", %{device: device} do
+      # Mock SNMP responses for discovery
+      expect(SnmpMock, :get, 6, fn _target, oid, _opts ->
+        case oid do
+          "1.3.6.1.2.1.1.1.0" -> {:ok, "Test Device"}
+          "1.3.6.1.2.1.1.2.0" -> {:ok, [1, 3, 6, 1, 4, 1, 9]}
+          "1.3.6.1.2.1.1.3.0" -> {:ok, 12_345}
+          "1.3.6.1.2.1.1.4.0" -> {:ok, "admin@test.com"}
+          "1.3.6.1.2.1.1.5.0" -> {:ok, "test-device"}
+          "1.3.6.1.2.1.1.6.0" -> {:ok, "Test Location"}
+        end
+      end)
+
+      # Mock interface discovery
+      expect(SnmpMock, :walk, fn _target, "1., _opts ->3.6.1.2.1.2.2.1.2" ->
+        {:ok, [%{oid: "1.3.6.1.2.1.2.2.1.2.1", value: "eth0"}]}
+      end)
+
+      # Mock neighbor discovery (LLDP) - empty
+      expect(SnmpMock, :walk, fn _target, "1., _opts ->0.8802.1.1.2.1.4.1.1.4" ->
+        {:ok, []}
+      end)
+
+      # Mock neighbor discovery (CDP) - empty
+      expect(SnmpMock, :walk, fn _target, "1., _opts ->3.6.1.4.1.9.9.23.1.2.1.1.4" ->
+        {:ok, []}
+      end)
+
+      assert :ok = DiscoveryWorker.perform(device.id)
+
+      # Verify SNMP device was created
+      snmp_device = Snmp.get_device(device.id)
+      assert snmp_device
+      assert snmp_device.sys_descr == "Test Device"
+      assert snmp_device.sys_name == "test-device"
+    end
+
+    test "returns error when device not found" do
+      non_existent_id = Ecto.UUID.generate()
+
+      assert {:error, :device_not_found} = DiscoveryWorker.perform(non_existent_id)
+    end
+
+    test "returns error when discovery fails", %{device: device} do
+      # Mock SNMP failure
+      expect(SnmpMock, :get, 6, fn _target, _oid, _opts ->
+        {:error, :timeout}
+      end)
+
+      assert {:error, _reason} = DiscoveryWorker.perform(device.id)
+    end
+
+    test "logs appropriate messages", %{device: device} do
+      import ExUnit.CaptureLog
+      # Mock SNMP responses
+      expect(SnmpMock, :get, 6, fn _target, oid, _opts ->
+        case oid do
+          "1.3.6.1.2.1.1.1.0" -> {:ok, "Test"}
+          "1.3.6.1.2.1.1.2.0" -> {:ok, [1, 3, 6, 1]}
+          "1.3.6.1.2.1.1.3.0" -> {:ok, 1}
+          "1.3.6.1.2.1.1.4.0" -> {:ok, ""}
+          "1.3.6.1.2.1.1.5.0" -> {:ok, "test"}
+          "1.3.6.1.2.1.1.6.0" -> {:ok, ""}
+        end
+      end)
+
+      expect(SnmpMock, :walk, 3, fn _target, _oid, _opts -> {:ok, []} end)
+
+      log =
+        capture_log(fn ->
+          DiscoveryWorker.perform(device.id)
+        end)
+
+      assert log =~ "Starting SNMP discovery for device #{device.id}"
+      assert log =~ "SNMP discovery completed successfully for device #{device.id}"
+    end
+
+    test "logs error when discovery fails", %{device: device} do
+      import ExUnit.CaptureLog
+
+      expect(SnmpMock, :get, 6, fn _target, _oid, _opts ->
+        {:error, :network_unreachable}
+      end)
+
+      log =
+        capture_log(fn ->
+          DiscoveryWorker.perform(device.id)
+        end)
+
+      assert log =~ "SNMP discovery failed for device #{device.id}"
+    end
+  end
+end
diff --git a/test/towerops/workers/monitor_worker_test.exs b/test/towerops/workers/monitor_worker_test.exs
new file mode 100644
index 00000000..3eea6334
--- /dev/null
+++ b/test/towerops/workers/monitor_worker_test.exs
@@ -0,0 +1,141 @@
+defmodule Towerops.Workers.MonitorWorkerTest do
+  use Towerops.DataCase, async: true
+
+  import Towerops.AccountsFixtures
+
+  alias Towerops.Monitoring
+  alias Towerops.Workers.MonitorWorker
+
+  setup do
+    user = user_fixture()
+    {:ok, organization} = Towerops.Organizations.create_organization(%{name: "Test Org"}, user.id)
+
+    {:ok, site} =
+      Towerops.Sites.create_site(%{
+        name: "Test Site",
+        organization_id: organization.id
+      })
+
+    {:ok, device} =
+      Towerops.Devices.create_device(%{
+        name: "Test Device",
+        # Use localhost for reliable testing
+        ip_address: "127.0.0.1",
+        monitoring_enabled: true,
+        site_id: site.id
+      })
+
+    {:ok, device: device, org: organization}
+  end
+
+  describe "perform/1" do
+    test "creates a check when monitoring is enabled", %{device: device} do
+      # Call perform - it will ping localhost
+      result = MonitorWorker.perform(device.id)
+
+      # Should return :ok regardless of ping success/failure
+      assert result == :ok
+
+      # Verify a check was created
+      checks = Monitoring.list_checks_for_device(device.id)
+      assert length(checks) == 1
+
+      check = hd(checks)
+      assert check.device_id == device.id
+      assert check.status in [:success, :failure]
+      assert check.checked_at
+
+      # If ping succeeded, should have response time
+      if check.status == :success do
+        assert is_float(check.response_time_ms)
+        assert check.response_time_ms >= 0
+      else
+        assert check.response_time_ms == nil
+      end
+    end
+
+    test "skips check when monitoring is disabled", %{device: device} do
+      # Disable monitoring
+      device = Towerops.Devices.update_device!(device, %{monitoring_enabled: false})
+
+      assert :ok = MonitorWorker.perform(device.id)
+
+      # Verify no check was created
+      checks = Monitoring.list_checks_for_device(device.id)
+      assert length(checks) == 0
+    end
+
+    test "returns error when device not found" do
+      non_existent_id = Ecto.UUID.generate()
+
+      assert {:error, :device_not_found} = MonitorWorker.perform(non_existent_id)
+    end
+
+    test "broadcasts update after check", %{device: device} do
+      # Subscribe to device topic
+      Phoenix.PubSub.subscribe(Towerops.PubSub, "device:#{device.id}")
+
+      MonitorWorker.perform(device.id)
+
+      # Verify broadcast was sent
+      assert_receive {:monitoring_check_updated, device_id}, 1000
+      assert device_id == device.id
+    end
+
+    test "creates failed check for unreachable host" do
+      user = user_fixture()
+      {:ok, organization} = Towerops.Organizations.create_organization(%{name: "Test Org"}, user.id)
+
+      {:ok, site} =
+        Towerops.Sites.create_site(%{
+          name: "Test Site",
+          organization_id: organization.id
+        })
+
+      # Use a non-routable IP (documentation range)
+      {:ok, device} =
+        Towerops.Devices.create_device(%{
+          name: "Unreachable Device",
+          ip_address: "192.0.2.1",
+          monitoring_enabled: true,
+          site_id: site.id
+        })
+
+      assert :ok = MonitorWorker.perform(device.id)
+
+      # Verify check was created as failure
+      checks = Monitoring.list_checks_for_device(device.id)
+      assert length(checks) == 1
+
+      check = hd(checks)
+      assert check.status == :failure
+      assert check.response_time_ms == nil
+    end
+
+    test "logs appropriate messages", %{device: device} do
+      import ExUnit.CaptureLog
+
+      log =
+        capture_log([level: :debug], fn ->
+          MonitorWorker.perform(device.id)
+        end)
+
+      assert log =~ "Starting monitoring check for device #{device.id}"
+      # Will either log "is up" or "is down" depending on ping result
+      assert log =~ device.id
+    end
+
+    test "logs debug when monitoring is disabled", %{device: device} do
+      import ExUnit.CaptureLog
+
+      device = Towerops.Devices.update_device!(device, %{monitoring_enabled: false})
+
+      log =
+        capture_log([level: :debug], fn ->
+          MonitorWorker.perform(device.id)
+        end)
+
+      assert log =~ "Device #{device.id} does not have monitoring enabled"
+    end
+  end
+end
diff --git a/test/towerops/workers/poll_worker_test.exs b/test/towerops/workers/poll_worker_test.exs
new file mode 100644
index 00000000..e94a1ee2
--- /dev/null
+++ b/test/towerops/workers/poll_worker_test.exs
@@ -0,0 +1,276 @@
+defmodule Towerops.Workers.PollWorkerTest do
+  use Towerops.DataCase, async: true
+
+  import Mox
+  import Towerops.AccountsFixtures
+
+  alias Towerops.Snmp
+  alias Towerops.Snmp.SnmpMock
+  alias Towerops.Workers.PollWorker
+
+  setup :verify_on_exit!
+
+  describe "perform/1" do
+    setup do
+      user = user_fixture()
+      {:ok, organization} = Towerops.Organizations.create_organization(%{name: "Test Org"}, user.id)
+
+      {:ok, site} =
+        Towerops.Sites.create_site(%{
+          name: "Test Site",
+          organization_id: organization.id
+        })
+
+      {:ok, device} =
+        Towerops.Devices.create_device(%{
+          name: "Test Device",
+          ip_address: "192.168.1.1",
+          snmp_enabled: true,
+          snmp_version: "2c",
+          snmp_community: "public",
+          snmp_port: 161,
+          site_id: site.id
+        })
+
+      snmp_device =
+        %Snmp.Device{}
+        |> Snmp.Device.changeset(%{
+          device_id: device.id,
+          sys_name: "test-device",
+          sys_descr: "Test Device"
+        })
+        |> Repo.insert!()
+
+      sensor =
+        %Snmp.Sensor{}
+        |> Snmp.Sensor.changeset(%{
+          snmp_device_id: snmp_device.id,
+          sensor_oid: "1.3.6.1.4.1.14988.1.1.3.10.0",
+          sensor_divisor: 10.0,
+          sensor_type: "temperature",
+          sensor_descr: "Temperature"
+        })
+        |> Repo.insert!()
+
+      interface =
+        %Snmp.Interface{}
+        |> Snmp.Interface.changeset(%{
+          snmp_device_id: snmp_device.id,
+          if_index: 1,
+          if_descr: "eth0"
+        })
+        |> Repo.insert!()
+
+      {:ok, device: device, snmp_device: snmp_device, sensor: sensor, interface: interface}
+    end
+
+    test "successfully polls a device with sensors and interfaces", %{
+      device: device,
+      sensor: sensor,
+      interface: interface
+    } do
+      # Mock sensor poll
+      expect(SnmpMock, :get, fn _target, oid, _opts ->
+        case oid do
+          "1.3.6.1.4.1.14988.1.1.3.10.0" -> {:ok, 350}
+          "1.3.6.1.2.1.2.2.1.10.1" -> {:ok, 1000}
+          "1.3.6.1.2.1.2.2.1.16.1" -> {:ok, 2000}
+          "1.3.6.1.2.1.2.2.1.14.1" -> {:ok, 0}
+          "1.3.6.1.2.1.2.2.1.20.1" -> {:ok, 0}
+          "1.3.6.1.2.1.2.2.1.13.1" -> {:ok, 0}
+          "1.3.6.1.2.1.2.2.1.19.1" -> {:ok, 0}
+          _ -> {:error, :no_such_object}
+        end
+      end)
+
+      # Mock neighbor discovery (LLDP) - empty
+      expect(SnmpMock, :walk, fn _target, "1., _opts ->0.8802.1.1.2.1.4.1.1.4" ->
+        {:ok, []}
+      end)
+
+      # Mock neighbor discovery (CDP) - empty
+      expect(SnmpMock, :walk, fn _target, "1., _opts ->3.6.1.4.1.9.9.23.1.2.1.1.4" ->
+        {:ok, []}
+      end)
+
+      assert :ok = PollWorker.perform(device.id)
+
+      # Verify sensor reading was created
+      sensor = Towerops.Repo.reload(sensor)
+      # 350 / 10.0 divisor
+      assert sensor.last_value == 35.0
+      assert sensor.last_checked_at
+
+      # Verify interface stat was created
+      stats = Snmp.list_interface_stats(interface.id)
+      assert length(stats) == 1
+      stat = hd(stats)
+      assert stat.if_in_octets == 1000
+      assert stat.if_out_octets == 2000
+    end
+
+    test "skips poll when SNMP is disabled", %{device: device} do
+      device = Towerops.Devices.update_device!(device, %{snmp_enabled: false})
+
+      assert :ok = PollWorker.perform(device.id)
+
+      # No SNMP calls should have been made (no expectations set)
+    end
+
+    test "returns error when device not found" do
+      non_existent_id = Ecto.UUID.generate()
+
+      assert {:error, :device_not_found} = PollWorker.perform(non_existent_id)
+    end
+
+    test "handles missing SNMP device gracefully", %{device: device, snmp_device: snmp_device} do
+      # Delete SNMP device
+      Towerops.Repo.delete!(snmp_device)
+
+      # Should not crash
+      assert :ok = PollWorker.perform(device.id)
+    end
+
+    test "creates sensor reading with error status on SNMP failure", %{
+      device: device,
+      sensor: sensor
+    } do
+      # Mock SNMP timeout
+      expect(SnmpMock, :get, fn _target, _oid, _opts ->
+        {:error, :timeout}
+      end)
+
+      # Mock neighbor discovery - empty
+      expect(SnmpMock, :walk, 2, fn _target, _oid, _opts -> {:ok, []} end)
+
+      PollWorker.perform(device.id)
+
+      # Verify error reading was created
+      readings = Snmp.list_sensor_readings(sensor.id)
+      assert length(readings) == 1
+      reading = hd(readings)
+      assert reading.status == "error"
+      assert reading.value == nil
+    end
+
+    test "updates sensor last_value and last_checked_at", %{device: device, sensor: sensor} do
+      expect(SnmpMock, :get, fn _target, _oid, _opts -> {:ok, 250} end)
+      expect(SnmpMock, :walk, 2, fn _target, _oid, _opts -> {:ok, []} end)
+
+      PollWorker.perform(device.id)
+
+      sensor = Towerops.Repo.reload(sensor)
+      # 250 / 10.0
+      assert sensor.last_value == 25.0
+      assert sensor.last_checked_at
+    end
+
+    test "creates interface stats for all interfaces", %{device: device, interface: interface} do
+      # Mock interface stats
+      expect(SnmpMock, :get, 6, fn _target, oid, _opts ->
+        case oid do
+          "1.3.6.1.2.1.2.2.1.10.1" -> {:ok, 1234}
+          "1.3.6.1.2.1.2.2.1.16.1" -> {:ok, 5678}
+          "1.3.6.1.2.1.2.2.1.14.1" -> {:ok, 10}
+          "1.3.6.1.2.1.2.2.1.20.1" -> {:ok, 20}
+          "1.3.6.1.2.1.2.2.1.13.1" -> {:ok, 5}
+          "1.3.6.1.2.1.2.2.1.19.1" -> {:ok, 3}
+          _ -> {:error, :no_such_object}
+        end
+      end)
+
+      expect(SnmpMock, :walk, 2, fn _target, _oid, _opts -> {:ok, []} end)
+
+      PollWorker.perform(device.id)
+
+      stats = Snmp.list_interface_stats(interface.id)
+      assert length(stats) == 1
+      stat = hd(stats)
+      assert stat.if_in_octets == 1234
+      assert stat.if_out_octets == 5678
+      assert stat.if_in_errors == 10
+      assert stat.if_out_errors == 20
+      assert stat.if_in_discards == 5
+      assert stat.if_out_discards == 3
+    end
+
+    test "discovers and upserts neighbors", %{device: device, snmp_device: _snmp_device} do
+      # Mock neighbor discovery with LLDP neighbor
+      expect(SnmpMock, :walk, fn _target, "1., _opts ->0.8802.1.1.2.1.4.1.1.4" ->
+        {:ok,
+         [
+           %{oid: "1.0.8802.1.1.2.1.4.1.1.4.0.1.1", value: <<1, 2, 3, 4, 5, 6>>},
+           # Chassis ID (MAC)
+           %{oid: "1.0.8802.1.1.2.1.4.1.1.5.0.1.1", value: 4}
+           # Chassis ID subtype (MAC)
+         ]}
+      end)
+
+      # Mock other LLDP OIDs
+      expect(SnmpMock, :walk, 4, fn _target, _oid, _opts -> {:ok, []} end)
+
+      # Mock CDP (empty)
+      expect(SnmpMock, :walk, fn _target, "1., _opts ->3.6.1.4.1.9.9.23.1.2.1.1.4" ->
+        {:ok, []}
+      end)
+
+      PollWorker.perform(device.id)
+
+      # Verify neighbor was created/updated
+      neighbors = Snmp.list_neighbors(device.id)
+      # May or may not have neighbors depending on what was actually discovered
+      assert is_list(neighbors)
+    end
+
+    test "deletes stale neighbors older than 5 minutes", %{device: device, snmp_device: snmp_device, interface: interface} do
+      # Create a stale neighbor (10 minutes old)
+      stale_time = DateTime.add(DateTime.utc_now(), -10, :minute)
+
+      stale_neighbor =
+        %Snmp.Neighbor{}
+        |> Snmp.Neighbor.changeset(%{
+          device_id: device.id,
+          interface_id: interface.id,
+          chassis_id: "old:neighbor",
+          remote_port_id: "port1",
+          last_seen_at: stale_time
+        })
+        |> Repo.insert!()
+
+      # Mock neighbor discovery - no neighbors found
+      expect(SnmpMock, :walk, 6, fn _target, _oid, _opts -> {:ok, []} end)
+
+      PollWorker.perform(device.id)
+
+      # Verify stale neighbor was deleted
+      assert Towerops.Repo.get(Towerops.Snmp.Neighbor, stale_neighbor.id) == nil
+    end
+
+    test "handles non-numeric sensor values", %{device: device} do
+      # Mock sensor returning string instead of number
+      expect(SnmpMock, :get, fn _target, _oid, _opts ->
+        {:ok, "not a number"}
+      end)
+
+      expect(SnmpMock, :walk, 2, fn _target, _oid, _opts -> {:ok, []} end)
+
+      # Should not crash
+      PollWorker.perform(device.id)
+    end
+
+    test "logs appropriate messages", %{device: device} do
+      import ExUnit.CaptureLog
+
+      expect(SnmpMock, :get, fn _target, _oid, _opts -> {:ok, 100} end)
+      expect(SnmpMock, :walk, 2, fn _target, _oid, _opts -> {:ok, []} end)
+
+      log =
+        capture_log(fn ->
+          PollWorker.perform(device.id)
+        end)
+
+      assert log =~ "Starting SNMP poll for device #{device.id}"
+      assert log =~ "SNMP poll completed for device #{device.id}"
+    end
+  end
+end