## **Cargo.toml**
```toml
[package]
name = "multiply_function"
version = "0.1.0"
edition = "2021"

[dependencies]

```

## **src/lib.rs**
```rust
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(-1, 5), -5);
        assert_eq!(solution(0, 10), 0);
    }
}
```

## **Build**
```bash
cargo build
```

## **Test**
```bash
cargo test
```



**Explanation:**

* **Cargo.toml:** This file defines the project's metadata, including its name, version, and dependencies.
* **src/lib.rs:**
    * `solution` function: Takes two integers (`a` and `b`) as input and returns their product.
    * `tests` module: Contains a test suite using the `#[cfg(test)]` attribute to ensure it only runs during
testing.
    * `test_solution`: A single test case that verifies the `solution` function's output for three different
inputs.

* **Build:**  The `cargo build` command compiles the Rust code into an executable file.
* **Test:** The `cargo test` command runs all tests defined in the project and reports the results (success or
failure).