optionchain_simulator 0.0.3

OptionChain-Simulator is a lightweight REST API service that simulates an evolving option chain with every request. It is designed for developers building or testing trading systems, backtesters, and visual tools that depend on option data streams but want to avoid relying on live data feeds.
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use crate::utils::ChainError;
use actix_web::HttpResponse;

pub(crate) fn map_error(error: ChainError) -> HttpResponse {
    match error {
        ChainError::NotFound(_) => {
            HttpResponse::NotFound().json(serde_json::json!({"error": error.to_string()}))
        }
        ChainError::InvalidState(_) => {
            HttpResponse::BadRequest().json(serde_json::json!({"error": error.to_string()}))
        }
        ChainError::SimulatorError(err) => {
            HttpResponse::Gone().json(serde_json::json!({"error": err}))
        }
        _ => HttpResponse::InternalServerError()
            .json(serde_json::json!({"error": "Internal server error".to_string()})),
    }
}

/// Tests for the `map_error` function.
#[cfg(test)]
mod tests {
    use super::*;
    use actix_web::body::to_bytes;
    use actix_web::http::StatusCode;
    use serde_json::Value;

    /// NotFound should map to 404 with the error message from `Display`.
    #[actix_web::test]
    async fn test_map_error_not_found() {
        let err = ChainError::NotFound("item_xyz".into());
        let resp: HttpResponse = map_error(err.clone());
        assert_eq!(resp.status(), StatusCode::NOT_FOUND);

        let body = to_bytes(resp.into_body()).await.unwrap();
        let json: Value = serde_json::from_slice(&body).unwrap();
        assert_eq!(json, serde_json::json!({"error": err.to_string()}));
    }

    /// InvalidState should map to 400 with the error message from `Display`.
    #[actix_web::test]
    async fn test_map_error_invalid_state() {
        let err = ChainError::InvalidState("bad_state".into());
        let resp: HttpResponse = map_error(err.clone());
        assert_eq!(resp.status(), StatusCode::BAD_REQUEST);

        let body = to_bytes(resp.into_body()).await.unwrap();
        let json: Value = serde_json::from_slice(&body).unwrap();
        assert_eq!(json, serde_json::json!({"error": err.to_string()}));
    }

    /// SimulatorError should map to 410 with the raw inner string.
    #[actix_web::test]
    async fn test_map_error_simulator_error() {
        let err = ChainError::SimulatorError("sim_fail".into());
        let resp: HttpResponse = map_error(err.clone());
        assert_eq!(resp.status(), StatusCode::GONE);

        let body = to_bytes(resp.into_body()).await.unwrap();
        let json: Value = serde_json::from_slice(&body).unwrap();
        assert_eq!(json, serde_json::json!({"error": "sim_fail"}));
    }

    /// Any other variant (e.g., SessionError) should map to 500 with a generic message.
    #[actix_web::test]
    async fn test_map_error_default() {
        let err = ChainError::SessionError("oops".into());
        let resp: HttpResponse = map_error(err);
        assert_eq!(resp.status(), StatusCode::INTERNAL_SERVER_ERROR);

        let body = to_bytes(resp.into_body()).await.unwrap();
        let json: Value = serde_json::from_slice(&body).unwrap();
        assert_eq!(json, serde_json::json!({"error": "Internal server error"}));
    }
}