leptos-rs/leptos · info

should serialize string

Error message

should serialize string

What it means

This is a test assertion inside the oco crate: serde_json::to_string(&Oco::Borrowed("foo")) is expected to succeed, since Oco<'a, str> serializes as a plain string. The expect fires only if serialization returns an Err, which would indicate a broken Serialize impl for the Oco type rather than a user-facing condition.

Source

Thrown at oco/src/lib.rs:733

    #[test]
    fn cloned_inplace_borrowed_str_should_make_borrowed_str_and_remain_borrowed(
    ) {
        let mut s: Oco<str> = Oco::Borrowed("hello");
        assert!(s.clone_inplace().is_borrowed());
        assert!(s.is_borrowed());
    }

    #[test]
    fn cloned_inplace_counted_str_should_make_counted_str_and_remain_counted() {
        let mut s: Oco<str> = Oco::Counted(Arc::from("hello"));
        assert!(s.clone_inplace().is_counted());
        assert!(s.is_counted());
    }

    #[test]
    fn serialization_works() {
        let s = serde_json::to_string(&Oco::Borrowed("foo"))
            .expect("should serialize string");
        assert_eq!(s, "\"foo\"");
    }

    #[test]
    fn deserialization_works() {
        let s: Oco<str> = serde_json::from_str("\"bar\"")
            .expect("should deserialize from string");
        assert_eq!(s, Oco::from(String::from("bar")));
    }
}

View on GitHub (pinned to 32d20f6c9d)

Solutions

1. Re-enable the `serde` feature of the oco crate so Serialize/Deserialize impls are compiled.
2. Fix or restore the Serialize impl for Oco so all variants (Borrowed, Counted, Owned) emit plain strings.
3. Check for serde/serde_json version incompatibilities introduced by Cargo.lock updates.
4. Run cargo test -p oco to confirm the fix.

Example fix

// before: feature missing in Cargo.toml
oco = { path = "../oco", default-features = false }

// after
oco = { path = "../oco", features = ["serde"] }

fn is_oco_str_serializable(v: &Oco<'_, str>) -> bool {
    serde_json::to_string(v).is_ok()
}

match serde_json::to_string(&value) {
    Ok(s) => s,
    Err(e) => { log::error!("oco serialization failed: {e}"); String::new() }
}

When it happens

Trigger: Only in the crate's own test suite (serialization_works): a regression in Oco's Serialize implementation, an incompatible serde_json version, or a feature-flag combination (e.g. serde feature off) that breaks serialization.

Common situations: Contributors bumping serde/serde_json versions, disabling default features, or modifying Oco's enum variants so the Serialize derive/impl no longer handles Borrowed correctly.

Related errors

• should deserialize from string
• Unsupported server function HTTP method: {method:?}
• {}
• Reading from a LocalResource outside Suspense in `ssr` mode
• at {location}, the `sandboxed-arenas` feature is active, but

AI-assisted analysis of leptos-rs/leptos@32d20f6c9d (2026-09-01). Data as JSON: /api/errors/8b775cfe59d2e6dd. Report an issue: GitHub.