thirdshift 0.11.1

//! Shared unit-test helpers: run signal-sensitive tests in isolated
//! processes so interruption and fixture environment changes cannot leak into
//! another test, and write executables other tests can't hold open.

use std::process::Command;

use crate::interrupt;

/// Exercise the fully qualified test once per recorded signal, installing
/// the handler only in the subprocess selected for that test.
pub(crate) fn with_recorded_signal(test_name: &str, exercise: impl FnOnce(libc::c_int)) {
    const TEST: &str = "THIRDSHIFT_TEST_SIGNAL_NAME";
    const SIGNAL: &str = "THIRDSHIFT_TEST_SIGNAL";
    if std::env::var(TEST).as_deref() == Ok(test_name) {
        interrupt::install().unwrap();
        exercise(std::env::var(SIGNAL).unwrap().parse().unwrap());
        return;
    }
    for signal in [libc::SIGINT, libc::SIGTERM, libc::SIGHUP] {
        let result = Command::new(std::env::current_exe().unwrap())
            .args(["--exact", test_name, "--nocapture"])
            .env(TEST, test_name)
            .env(SIGNAL, signal.to_string())
            .output()
            .unwrap();
        assert!(
            result.status.success(),
            "{test_name}, signal {signal}: {result:?}"
        );
    }
}

/// Write `contents` to `path` as an executable. A child process writes it,
/// not this one: a file this process held open for writing would be
/// inherited by whatever another test spawns meanwhile, and couldn't be run
/// until that let go of it ("Text file busy").
pub(crate) fn write_executable(path: &std::path::Path, contents: &str) {
    use std::io::Write;
    use std::process::Stdio;

    let mut child = Command::new("sh")
        .args(["-c", "cat > \"$1\" && chmod 755 \"$1\"", "sh"])
        .arg(path)
        .stdin(Stdio::piped())
        .spawn()
        .unwrap();
    child
        .stdin
        .take()
        .unwrap()
        .write_all(contents.as_bytes())
        .unwrap();
    let status = child.wait().unwrap();
    assert!(status.success(), "could not write {}", path.display());
}

/// Run a single test with a Git shim in an isolated child. The parent receives
/// its captured output; the selected child exercises the real interface.
pub(crate) fn git_fault(name: &str, script: &str) -> Option<std::process::Output> {
    if std::env::var("THIRDSHIFT_GIT_FAULT_TEST").as_deref() == Ok(name) {
        return None;
    }
    let temp = tempfile::TempDir::new().unwrap();
    let real_git = Command::new("sh")
        .args(["-c", "command -v git"])
        .output()
        .unwrap();
    assert!(real_git.status.success());
    let shim = temp.path().join("git");
    write_executable(
        &shim,
        &format!("#!/bin/sh\nset -e\n{script}\nexec \"$THIRDSHIFT_REAL_GIT\" \"$@\"\n"),
    );
    let search = std::env::var_os("PATH").unwrap();
    let path = std::env::join_paths(
        std::iter::once(temp.path().to_path_buf()).chain(std::env::split_paths(&search)),
    )
    .unwrap();
    let output = Command::new(std::env::current_exe().unwrap())
        .args(["--exact", name, "--nocapture"])
        .env("PATH", path)
        .env("THIRDSHIFT_GIT_FAULT_TEST", name)
        .env(
            "THIRDSHIFT_REAL_GIT",
            String::from_utf8(real_git.stdout).unwrap().trim(),
        )
        .env("THIRDSHIFT_FAULT_MARKER", temp.path().join("fault"))
        .output()
        .unwrap();
    assert!(output.status.success(), "{output:?}");
    Some(output)
}