examples/components/echo/rust/src/main.rs

// Copyright 2021 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// [START imports]
use tracing::info;
// [END imports]

// [START main]
#[fuchsia::main(logging = true)]
async fn main() -> Result<(), anyhow::Error> {
    // Read program arguments, and strip off binary name
    let mut args: Vec<String> = std::env::args().collect();
    args.remove(0);

    // Include environment variables
    let animal = std::env::var("FAVORITE_ANIMAL").unwrap();
    args.push(animal);

    // Print a greeting to syslog
    info!("Hello, {}!", greeting(&args));

    Ok(())
}
// [END main]

// [START greeting]
// Return a proper greeting for the list
fn greeting(names: &Vec<String>) -> String {
    // Join the list of names based on length
    match names.len() {
        0 => String::from("Nobody"),
        1 => names.join(""),
        2 => names.join(" and "),
        _ => names.join(", "),
    }
}
// [END greeting]

// [START test_mod]
#[cfg(test)]
mod tests {
    #[fuchsia::test]
    async fn test_greet_one() {
        let names = vec![String::from("Alice")];
        let expected = "Alice";
        assert_eq!(super::greeting(&names), expected);
    }

    #[fuchsia::test]
    async fn test_greet_two() {
        let names = vec![String::from("Alice"), String::from("Bob")];
        let expected = "Alice and Bob";
        assert_eq!(super::greeting(&names), expected);
    }

    #[fuchsia::test]
    async fn test_greet_three() {
        let names = vec![String::from("Alice"), String::from("Bob"), String::from("Spot")];
        let expected = "Alice, Bob, Spot";
        assert_eq!(super::greeting(&names), expected);
    }
}
// [END test_mod]