rust/library/std/tests/env.rs

use std::env::*;
use std::ffi::{OsStr, OsString};

use rand::distributions::Alphanumeric;
use rand::{thread_rng, Rng};

fn make_rand_name() -> OsString {
    let rng = thread_rng();
    let n = format!("TEST{}", rng.sample_iter(&Alphanumeric).take(10).collect::<String>());
    let n = OsString::from(n);
    assert!(var_os(&n).is_none());
    n
}

fn eq(a: Option<OsString>, b: Option<&str>) {
    assert_eq!(a.as_ref().map(|s| &**s), b.map(OsStr::new).map(|s| &*s));
}

#[test]
fn test_set_var() {
    let n = make_rand_name();
    set_var(&n, "VALUE");
    eq(var_os(&n), Some("VALUE"));
}

#[test]
fn test_remove_var() {
    let n = make_rand_name();
    set_var(&n, "VALUE");
    remove_var(&n);
    eq(var_os(&n), None);
}

#[test]
fn test_set_var_overwrite() {
    let n = make_rand_name();
    set_var(&n, "1");
    set_var(&n, "2");
    eq(var_os(&n), Some("2"));
    set_var(&n, "");
    eq(var_os(&n), Some(""));
}

#[test]
#[cfg_attr(target_os = "emscripten", ignore)]
fn test_var_big() {
    let mut s = "".to_string();
    let mut i = 0;
    while i < 100 {
        s.push_str("aaaaaaaaaa");
        i += 1;
    }
    let n = make_rand_name();
    set_var(&n, &s);
    eq(var_os(&n), Some(&s));
}

#[test]
#[cfg_attr(target_os = "emscripten", ignore)]
fn test_env_set_get_huge() {
    let n = make_rand_name();
    let s = "x".repeat(10000);
    set_var(&n, &s);
    eq(var_os(&n), Some(&s));
    remove_var(&n);
    eq(var_os(&n), None);
}

#[test]
fn test_env_set_var() {
    let n = make_rand_name();

    let mut e = vars_os();
    set_var(&n, "VALUE");
    assert!(!e.any(|(k, v)| { &*k == &*n && &*v == "VALUE" }));

    assert!(vars_os().any(|(k, v)| { &*k == &*n && &*v == "VALUE" }));
}