feat(api): handle main unit disconnections (#147)

src/elmo/api/client.py

@@ -15,6 +15,7 @@
     CodeError,
     CommandError,
     CredentialError,
+    DeviceDisconnectedError,
     InvalidToken,
     LockError,
     ParseError,
@@ -622,8 +623,14 @@ def query(self, query):
             # Bail-out if the query is not recognized
             raise QueryNotValid()
 
-        response = self._session.post(endpoint, data={"sessionId": self._session_id})
-        response.raise_for_status()
+        try:
+            response = self._session.post(endpoint, data={"sessionId": self._session_id})
+            response.raise_for_status()
+        except HTTPError as err:
+            # Handle the case when the device is disconnected
+            if err.response.status_code == 403 and "Centrale non connessa" in err.response.text:
+                raise DeviceDisconnectedError
+            raise err
 
         if query in [q.SECTORS, q.INPUTS, q.OUTPUTS]:
             # Retrieve description or use the cache

src/elmo/api/exceptions.py

@@ -74,3 +74,9 @@ class CommandError(APIException):
     """Exception raised when the API returns an error response after issuing a command."""
 
     default_message = "An error occurred while executing the command."
+
+
+class DeviceDisconnectedError(APIException):
+    """Exception raised when the device is disconnected."""
+
+    default_message = "Unable to execute commands. Device is disconnected."

tests/test_client.py

@@ -10,6 +10,7 @@
     CodeError,
     CommandError,
     CredentialError,
+    DeviceDisconnectedError,
     InvalidToken,
     LockError,
     LockNotAcquired,
@@ -2414,6 +2415,22 @@ def test_client_query_invalid_response(server, mocker):
         client.query(query.SECTORS)
 
 
+def test_client_query_unit_disconnected(server, mocker):
+    # Ensure that the client catches and raises an exception when the unit is disconnected
+    server.add(
+        responses.POST,
+        "https://example.com/api/areas",
+        body='"Centrale non connessa"',
+        status=403,
+    )
+    client = ElmoClient(base_url="https://example.com", domain="domain")
+    client._session_id = "test"
+    mocker.patch.object(client, "_get_descriptions")
+    # Test
+    with pytest.raises(DeviceDisconnectedError):
+        client.query(query.SECTORS)
+
+
 def test_client_get_alerts_status(server):
     """Should query a Elmo system to retrieve alerts status."""
     html = """