Fix container resource sampling and surface collection failures

agent/tests/test_agent.py

@@ -124,6 +124,7 @@ class AgentTests(unittest.TestCase):
         self.assertEqual(samples[0]["cpuCores"], 1.5)
         self.assertEqual(samples[0]["memoryBytes"], int(384.5 * 1024 ** 2))
         self.assertGreater(samples[0]["uptimeSeconds"], 300)
+        self.assertEqual(call.call_args_list[0].args, ("container", "ls", "--filter", "label=io.electric-cherry.managed=true", "--no-trunc", "--format", "{{.ID}}"))
         self.assertEqual(call.call_args_list[-1].args, ("stats", "--no-stream", "--no-trunc", "--format", "{{json .}}", name))
 
     def test_instance_resources_ignores_stopped_foreign_and_mismatched_containers(self):
@@ -149,7 +150,13 @@ class AgentTests(unittest.TestCase):
         with patch.object(self.docker, "call", side_effect=["container-id\n", json.dumps([self.resource_container()]), json.dumps(good)]):
             self.assertEqual(self.agent.instance_resources()[0]["cpuCores"], 0)
         with patch.object(self.agent, "instance_resources", side_effect=AgentError("timed out")):
-            self.assertNotIn("instanceResources", self.agent.inventory())
+            inventory = self.agent.inventory()
+            self.assertNotIn("instanceResources", inventory)
+            self.assertIn("sampling failed", inventory["instanceResourcesError"])
+        with patch.object(self.agent, "instance_resources", return_value=[]):
+            inventory = self.agent.inventory()
+            self.assertEqual(inventory["instanceResources"], [])
+            self.assertNotIn("instanceResourcesError", inventory)
 
     def operation(self, kind, payload=None, op_id="operation-1", generation=1):
         return {"id": op_id, "kind": kind, "instanceId": INSTANCE, "generation": generation, "payload": payload or {}}