yuzu-core 0.5.1

Pure, I/O-free backtest engine core for US equity strategies.
Documentation 
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//! [`EngineError`]: shape violations from panel construction and evaluation failures.

use std::fmt;

#[derive(Debug)]
pub enum EngineError {
    ShapeMismatch {
        rows: usize,
        cols: usize,
        data_len: usize,
    },
    Eval(String),
}

impl fmt::Display for EngineError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            EngineError::ShapeMismatch {
                rows,
                cols,
                data_len,
            } => {
                write!(f, "shape mismatch: {rows}x{cols} != data len {data_len}")
            }
            EngineError::Eval(m) => write!(f, "eval error: {m}"),
        }
    }
}

impl std::error::Error for EngineError {}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn display_messages() {
        let e = EngineError::ShapeMismatch {
            rows: 1,
            cols: 2,
            data_len: 3,
        };
        assert!(e.to_string().contains("shape mismatch"));
        assert!(EngineError::Eval("boom".into())
            .to_string()
            .contains("boom"));
    }
}