blocker/desktop/platform-linux/src/enforce/tests.rs

//! Tests for the enforcement ladder.
//!
//! `expect`/`unwrap`/`panic` are allowed here, scoped to this module with the
//! reason stated: a failed assertion or a missing `sleep` binary is a broken
//! test, not a runtime condition to handle gracefully.

#![allow(
    clippy::unwrap_used,
    clippy::expect_used,
    clippy::panic,
    reason = "test fixtures: a failed assertion is a broken test, not a runtime condition"
)]

use super::*;

/// A child process can be frozen, reported frozen, and thawed again.
///
/// Deliberately *not* done to the test process itself. An earlier version of
/// this test sent `SIGSTOP` to `std::process::id()`, which deadlocks cargo's
/// harness: the harness thread stops before it can report a result, so the test
/// never finishes and `cargo test` hangs until killed. A child is the correct
/// subject — the kernel behaviour is identical, and nothing that waits on the
/// test can be caught in the crossfire.
#[test]
fn a_child_process_freezes_reports_and_thaws() {
    let mut child = std::process::Command::new("sleep").arg("30").spawn().expect("spawn sleep");
    let pid = child.id();

    assert!(!is_frozen(pid).expect("read child stat"), "child starts running");

    apply(Enforcement::Freeze, pid).expect("SIGSTOP the child");

    // The signal is delivered asynchronously, so poll briefly rather than
    // sleeping a fixed amount: a slow machine should not flake the test.
    let mut frozen = false;
    for _ in 0..50 {
        if is_frozen(pid).unwrap_or(false) {
            frozen = true;
            break;
        }
        std::thread::sleep(std::time::Duration::from_millis(20));
    }
    assert!(frozen, "the child should report stopped after SIGSTOP");

    thaw(pid).expect("SIGCONT the child");

    let mut running = false;
    for _ in 0..50 {
        if !is_frozen(pid).unwrap_or(false) {
            running = true;
            break;
        }
        std::thread::sleep(std::time::Duration::from_millis(20));
    }
    assert!(running, "the child should be running again after SIGCONT");

    let _ = child.kill();
    let _ = child.wait();
}

/// Signalling a pid we cannot signal is an error, never a panic.
///
/// CLAUDE.md section 0 rule 5: a fallible OS call must not abort the daemon.
/// A daemon that panics takes enforcement down with it.
#[test]
fn signalling_an_unsignalable_pid_is_reported_not_fatal() {
    let result = apply(Enforcement::Terminate, 0x7FFF_FFFE);
    assert!(result.is_err(), "an unsignalable pid must be an error");
}

/// Actions that need a window or a compositor are no-ops here, and succeed.
#[test]
fn compositor_actions_are_no_ops_at_this_layer() {
    assert!(apply(Enforcement::BlockScreen, 0).is_ok());
    assert!(apply(Enforcement::Minimise, 0).is_ok());
}

/// A missing process is distinguished from other signalling failures.
#[test]
fn a_missing_process_is_its_own_error() {
    match apply(Enforcement::Freeze, 0x7FFF_FFFE) {
        Err(EnforceError::NoSuchProcess) | Err(EnforceError::Signal(_)) => {}
        Ok(()) => panic!("signalling a nonexistent pid must not succeed"),
    }
}

/// Freezing is reversible and non-destructive — the reason it is preferred to
/// terminating.
#[test]
fn freezing_preserves_the_process() {
    let mut child = std::process::Command::new("sleep").arg("30").spawn().expect("spawn sleep");
    let pid = child.id();

    apply(Enforcement::Freeze, pid).expect("SIGSTOP");
    for _ in 0..50 {
        if is_frozen(pid).unwrap_or(false) {
            break;
        }
        std::thread::sleep(std::time::Duration::from_millis(20));
    }
    thaw(pid).expect("SIGCONT");

    // Still alive, and its exit status is still readable — nothing was destroyed.
    assert!(!is_frozen(pid).unwrap_or(true), "the child must be running again after SIGCONT");
    assert_eq!(
        child.try_wait().expect("try_wait").map(|s| s.to_string()),
        None,
        "the process must still be running after freeze and thaw, not reaped"
    );

    let _ = child.kill();
    let _ = child.wait();
}