## **Cargo.toml**

```toml
[package]
name = "multiply"
version = "0.1.0"
edition = "2021"

[dependencies]
```

## **src/lib.rs**

```rust
pub fn solution(a: i32, b: i32) -> i32 {
    a * b
}

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

    #[test]
    fn test_solution() {
        assert_eq!(solution(2, 3), 6);
        assert_eq!(solution(-2, 3), -6);
        assert_eq!(solution(0, 5), 0);
    }
}
```

## **Build**

```bash
cargo build
```

## **Test**

```bash
cargo test
```

This code defines a function `solution` that takes two integers (`a` and `b`) as parameters and returns their
product. The `tests` module contains three test cases to verify the functionality of the function:


*  `test_solution()`: This test case checks if multiplying 2 by 3 results in 6, -2 by 3 results in -6, and 0 by 5
results in 0.

To build and run the tests, execute the commands mentioned in the "Build" and "Test" sections respectively.