use std::fs::{self, DirEntry};
use std::io;
use std::path::Path;

#[test]
fn test_missing_tests() {
    explore_directory(Path::new("./tests")).unwrap();
}

/*
Test for missing files.

Since rs files are alphabetically before stderr/stdout, we can sort by the full name
and iter in that order. If we've seen the file stem for the first time and it's not
a rust file, it means the rust file has to be missing.
*/
fn explore_directory(dir: &Path) -> io::Result<()> {
    let mut current_file = String::new();
    let mut files: Vec<DirEntry> = fs::read_dir(dir)?.filter_map(Result::ok).collect();
    files.sort_by_key(|e| e.path());
    for entry in files.iter() {
        let path = entry.path();
        if path.is_dir() {
            explore_directory(&path)?;
        } else {
            let file_stem = path.file_stem().unwrap().to_str().unwrap().to_string();
            match path.extension() {
                Some(ext) => {
                    match ext.to_str().unwrap() {
                        "rs" => current_file = file_stem.clone(),
                        "stderr" | "stdout" => {
                            assert_eq!(
                                file_stem,
                                current_file,
                                "{}",
                                format!("Didn't see a test file for {:}", path.to_str().unwrap())
                            );
                        },
                        _ => continue,
                    };
                },
                None => {},
            }
        }
    }
    Ok(())
}