src/tools/miri/tests/pass/shims/env/var.rs

//@compile-flags: -Zmiri-deterministic-concurrency
use std::{env, thread};

fn main() {
    // Test that miri environment is isolated when communication is disabled.
    // (`MIRI_ENV_VAR_TEST` is set by the test harness.)
    assert_eq!(env::var("MIRI_ENV_VAR_TEST"), Err(env::VarError::NotPresent));

    // Test base state.
    println!("{:#?}", env::vars().collect::<Vec<_>>());
    assert_eq!(env::var("MIRI_TEST"), Err(env::VarError::NotPresent));

    // Set the variable.
    env::set_var("MIRI_TEST", "the answer");
    assert_eq!(env::var("MIRI_TEST"), Ok("the answer".to_owned()));
    println!("{:#?}", env::vars().collect::<Vec<_>>());

    // Change the variable.
    env::set_var("MIRI_TEST", "42");
    assert_eq!(env::var("MIRI_TEST"), Ok("42".to_owned()));
    println!("{:#?}", env::vars().collect::<Vec<_>>());

    // Remove the variable.
    env::remove_var("MIRI_TEST");
    assert_eq!(env::var("MIRI_TEST"), Err(env::VarError::NotPresent));
    println!("{:#?}", env::vars().collect::<Vec<_>>());

    // Do things concurrently, to make sure there's no data race.
    // We disable preemption to make sure the lock is not contended;
    // that means we don't hit e.g. the futex codepath on Android (which we don't support).
    let t = thread::spawn(|| {
        env::set_var("MIRI_TEST", "42");
    });
    env::set_var("MIRI_TEST", "42");
    t.join().unwrap();
}