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// src/lib.rs — library with unit tests and doc tests

/// Adds two numbers together.
///
/// # Examples
///
/// ```
/// assert_eq!(my_lib::add(2, 3), 5);
/// ```
pub fn add(a: i32, b: i32) -> i32 {
    a + b
}

pub fn divide(a: f64, b: f64) -> Option<f64> {
    if b == 0.0 { None } else { Some(a / b) }
}

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

#[test]
    fn test_add_positive() {
        assert_eq!(add(2, 3), 5);
    }

#[test]
    fn test_add_negative() {
        assert_eq!(add(-1, -2), -3);
    }

#[test]
    fn test_divide_normal() {
        assert!((divide(10.0, 4.0).unwrap() - 2.5).abs() < 1e-10);
    }

#[test]
    fn test_divide_by_zero() {
        assert_eq!(divide(1.0, 0.0), None);
    }

#[test]
    #[should_panic(expected = "intentional")]
    fn test_panic() {
        panic!("intentional panic for demonstration");
    }
}

// tests/integration_test.rs  (separate file in tests/ directory)
// use my_lib;
// #[test]
// fn integration_add() {
//     assert_eq!(my_lib::add(10, 20), 30);
// }

// Run all tests:              cargo test
// Run a specific test:        cargo test test_add_positive
// Run doc tests only:         cargo test --doc
// Run integration tests only: cargo test --test integration_test