greet.mod.rs

mod test;

#[tauri::command]
pub fn greet(name: &str) -> String {
    format!("Hello, {}! You've been greeted from Rust!", name)
}

greet.test.mod.rs

use crate::greet;

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

    #[test]
    fn test_greet() {
        assert_eq!(greet("Johnny"), "Hello, Johnny! You've been greeted from Rust!");
    }

    #[test]
    fn test_greet_badly() {
        assert_eq!(greet("Johnny"), "Hello, Bonny! You've been greeted from Rust!");
    }
}

main.rs

#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]

mod greet;
use crate::greet::greet;

fn main() {
    tauri::Builder::default()
        .plugin(tauri_plugin_oauth::init())
        .invoke_handler(tauri::generate_handler![greet])
        .run(tauri::generate_context!())
        .expect("error while running tauri application");
}