Create an ApplianceTemplate class

tests/controller/test_controller.py

@@ -24,10 +24,7 @@ import aiohttp
 from unittest.mock import MagicMock
 from tests.utils import AsyncioMagicMock, asyncio_patch
 
-from gns3server.controller import Controller
 from gns3server.controller.compute import Compute
-from gns3server.controller.project import Project
-from gns3server.config import Config
 from gns3server.version import __version__
 
 
@@ -467,5 +464,5 @@ def test_get_free_project_name(controller, async_run):
     assert controller.get_free_project_name("Hello") == "Hello"
 
 
-def test_appliances(controller):
-    assert len(controller.appliances) > 0
+def test_appliance_templates(controller):
+    assert len(controller.appliance_templates) > 0