databendlabs/databend · warning

expect InvalidReply

Error message

expect InvalidReply

What it means

This is a test-only assertion inside test_valid_reply in the txn reply module. The test constructs a RaftReply whose data cannot be decoded and expects the reply converter to produce an InvalidReply error variant; if it returns any other variant the unreachable!() panics with 'expect InvalidReply'. End users only encounter this if running or modifying the test suite — it is a guard that the error-decoding contract holds.

Solutions

1. Fix the reply conversion so undecodable RaftReply.data maps to ErrorCode::InvalidReply whose message starts with 'InvalidReply: can not decode RaftReply.data'
2. Ensure new RaftFields/error variants are added to the From<RaftReply> conversion match arms
3. Run `cargo test -p databend-meta -- test_valid_reply` to confirm the conversion contract

Example fix

// before
_ => { /* returned Ok(reply) or wrong error */ }
// after
impl From<RaftReply> for TxnReply {
    fn from(r: RaftReply) -> Self {
        ... map decode failure of r.data to ErrorCode::InvalidReply("can not decode RaftReply.data") ...
    }
}

// test-only; validate reply conversion contract in tests
assert!(matches!(TxnReply::from(bad_reply).error, ErrorCode::InvalidReply(_)));

When it happens

Trigger: Modifying the reply conversion code (RaftReply -> TxnReply) so that undecodable .data no longer maps to ErrorCode::InvalidReply, then running the meta-api tests; or adding a new RaftFields variant not covered by the conversion match.

Common situations: Refactoring src/meta/api/src/txn/reply.rs error handling; introducing a new error representation in RaftReply; breaking serde round-trip of RaftReply.data.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

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AI-assisted analysis of databendlabs/databend@288d84d76e (2026-09-11). Data as JSON: /api/errors/1c227f4b3a9f6aa9. Report an issue: GitHub.

Appendix: source

Thrown at src/meta/api/src/txn/reply.rs:72

    #[test]
    fn test_valid_reply() -> anyhow::Result<()> {
        // Unable to decode `.data`

        let msg = RaftReply {
            data: "foo".to_string(),
            error: "".to_string(),
        };
        let res: Result<Foo, MetaAPIError> = reply_to_api_result(msg);
        match res {
            Err(MetaAPIError::NetworkError(MetaNetworkError::InvalidReply(inv_reply))) => {
                assert!(
                    inv_reply
                        .to_string()
                        .starts_with("InvalidReply: can not decode RaftReply.data")
                );
            }
            _ => {
                unreachable!("expect InvalidReply")
            }
        }

        // Unable to decode `.error`

        let msg = RaftReply {
            data: "".to_string(),
            error: "foo".to_string(),
        };
        let res: Result<Foo, MetaAPIError> = reply_to_api_result(msg);
        match res {
            Err(MetaAPIError::NetworkError(MetaNetworkError::InvalidReply(inv_reply))) => {
                assert!(
                    inv_reply
                        .to_string()
                        .starts_with("InvalidReply: can not decode RaftReply.error")
                );
            }

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