Fix deserialization of empty messages

crates/teloxide-core/CHANGELOG.md

@@ -32,8 +32,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Deserialization of `ApiError::CantParseEntities` ([#839][pr839])
+- Deserialization of empty (content-less) messages that can sometimes appear as a part of callback query ([#850][pr850], issue [#873][issue873])
 
 [pr839]: https://github.com/teloxide/teloxide/pull/839
+[pr879]: https://github.com/teloxide/teloxide/pull/879
+[issue873]: https://github.com/teloxide/teloxide/issues/873
 
 ## 0.9.1 - 2023-02-15
 

crates/teloxide-core/src/types/message.rs

@@ -78,6 +78,9 @@ pub enum MessageKind {
     VideoChatEnded(MessageVideoChatEnded),
     VideoChatParticipantsInvited(MessageVideoChatParticipantsInvited),
     WebAppData(MessageWebAppData),
+    /// An empty, content-less message, that can appear in callback queries
+    /// attached to old messages.
+    Empty {},
 }
 
 #[serde_with_macros::skip_serializing_none]
@@ -1446,6 +1449,7 @@ impl Message {
 
 #[cfg(test)]
 mod tests {
+    use cool_asserts::assert_matches;
     use serde_json::from_str;
 
     use crate::types::*;
@@ -1920,4 +1924,13 @@ mod tests {
 
         let _: Message = serde_json::from_str(json).unwrap();
     }
+
+    /// Regression test for <https://github.com/teloxide/teloxide/issues/873>
+    #[test]
+    fn empty_message() {
+        let json = r#"{"chat": {"first_name": "FN", "id": 1234567890, "type": "private"}, "date": 0, "message_id": 875400}"#;
+
+        let msg: Message = serde_json::from_str(json).unwrap();
+        assert_matches!(msg.kind, MessageKind::Empty {})
+    }
 }