test(api-thermal): update thermal manager tests

tests/integration/study_data_blueprint/test_thermal.py

@@ -423,7 +423,7 @@ def test_lifecycle(
         )
         assert res.status_code == 200, res.json()
         fr_gas_conventional_id = res.json()["id"]
-        assert fr_gas_conventional_id == transform_name_to_id(fr_gas_conventional, lower=False)
+        assert fr_gas_conventional_id == transform_name_to_id(fr_gas_conventional, lower=True)
         # noinspection SpellCheckingInspection
         fr_gas_conventional_cfg = {
             **fr_gas_conventional_props,
@@ -443,6 +443,17 @@ def test_lifecycle(
         }
         assert res.json() == fr_gas_conventional_cfg
 
+        # Check for duplicate thermal cluster
+        res = client.post(
+            f"/v1/studies/{study_id}/areas/{area_id}/clusters/thermal",
+            headers={"Authorization": f"Bearer {user_access_token}"},
+            json=fr_gas_conventional_props,
+        )
+        assert res.json() == {
+            "description": f"Thermal cluster '{fr_gas_conventional_id}' already exists in the area '{area_id}'.",
+            "exception": "CommandApplicationError",
+        }
+
         # reading the properties of a thermal cluster
         res = client.get(
             f"/v1/studies/{study_id}/areas/{area_id}/clusters/thermal/{fr_gas_conventional_id}",