Added test for get_available_lags function.

test/services/test_netbox.py

 """
 Unit tests for testing the netbox client
 """
+import uuid
 from os import PathLike
+from unittest.mock import patch, Mock
+
 import responses
 
 from gso.services.netbox_client import NetBoxClient
@@ -60,3 +63,26 @@ def test_get_all_interfaces(data_config_filename: PathLike):
 
     assert result is not None
     assert len(result) == num_iface
+
+
+@patch("gso.services.netbox_client.Router.from_subscription")
+@patch("gso.services.netbox_client.pynetbox.api")
+def test_get_available_lags(mock_api, mock_from_subscription, data_config_filename: PathLike):
+    router_id = uuid.uuid4()
+    feasible_lags = [f"LAG-{i}" for i in range(1, 10)]
+
+    # Mock the pynetbox API instance
+    mock_netbox = mock_api.return_value
+    mock_filter = mock_netbox.dcim.interfaces.filter
+    mock_filter.return_value = [{"name": f"LAG-{i}", "type": "lag"} for i in range(1, 4)]
+
+    # Mock the Router.from_subscription method
+    mock_subscription = mock_from_subscription.return_value
+    mock_router = mock_subscription.router
+    mock_router.router_fqdn = "test_router"
+
+    netbox_client = NetBoxClient()
+    result = netbox_client.get_available_lags(router_id)
+
+    # Check the result of the function
+    assert result == [lag for lag in feasible_lags if lag not in [f"LAG-{i}" for i in range(1, 4)]]