Function generate_resources 

pub fn generate_resources<P: AsRef<Path>, G: AsRef<Path>>(
    project_dir: P,
    filter: Option<fn(p: &Path) -> bool>,
    generated_filename: G,
    fn_name: &str,
) -> Result<()>

Generate resources for project_dir using filter. Result saved in generated_filename and function named as fn_name.

in build.rs:

use std::{env, path::Path};
use static_files::resource::generate_resources;

fn main() {
    let out_dir = env::var("OUT_DIR").unwrap();
    let generated_filename = Path::new(&out_dir).join("generated.rs");
    generate_resources("./tests", None, generated_filename, "generate").unwrap();
}

in main.rs:

include!(concat!(env!("OUT_DIR"), "/generated.rs"));

fn main() {
    let generated_file = generate();

    assert_eq!(generated_file.len(), 4);
}