KanbanGit/native/src-tauri/src/updates.rs

use semver::Version;
use serde::{Deserialize, Serialize};
use std::{
    fs,
    io::Read,
    path::Path,
    sync::Mutex,
    time::{Duration, Instant},
};
use tauri::{
    webview::{NewWindowResponse, PageLoadEvent},
    AppHandle, Manager, Url, WebviewUrl, WebviewWindowBuilder,
};
use tauri_plugin_updater::{Update, UpdaterExt};

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
struct Source {
    base_url: String,
    public_key: String,
}
fn source() -> &'static Source {
    static SOURCE: std::sync::LazyLock<Source> = std::sync::LazyLock::new(|| {
        serde_json::from_str(include_str!("../../update-source.json"))
            .expect("Bundled update source must be valid")
    });
    &SOURCE
}

#[derive(Clone, Debug, Deserialize, Serialize)]
#[serde(rename_all = "camelCase")]
struct Preferences {
    automatic: bool,
    interval_hours: u64,
}
impl Default for Preferences {
    fn default() -> Self {
        Self {
            automatic: true,
            interval_hours: 6,
        }
    }
}
impl Preferences {
    fn valid(&self) -> bool {
        [1, 6, 24].contains(&self.interval_hours)
    }
}

#[derive(Clone, Serialize)]
#[serde(rename_all = "camelCase")]
struct View {
    phase: &'static str,
    current_version: String,
    build: String,
    version: Option<String>,
    notes: Option<String>,
    downloaded: u64,
    total: Option<u64>,
    error: Option<&'static str>,
    preferences: Preferences,
}
struct State {
    view: View,
    update: Option<Update>,
    last_check: Option<Instant>,
}
impl State {
    fn busy(&self) -> bool {
        matches!(
            self.view.phase,
            "checking" | "downloading" | "verifying" | "installing" | "restarting"
        )
    }
    fn begin_check(&mut self, manual: bool, now: Instant) -> bool {
        if self.busy()
            || (!manual
                && (!self.view.preferences.automatic
                    || self.last_check.is_some_and(|last| {
                        now.duration_since(last)
                            < Duration::from_secs(self.view.preferences.interval_hours * 3600)
                    })))
        {
            return false;
        }
        self.last_check = Some(now);
        self.view.phase = "checking";
        self.view.error = None;
        self.update = None;
        self.view.version = None;
        self.view.notes = None;
        true
    }
}
fn target() -> String {
    format!("{}-apple-darwin", std::env::consts::ARCH)
}
fn feed_url() -> Url {
    Url::parse(&format!("{}/{}/latest.json", source().base_url, target())).unwrap()
}
fn newer_stable(current: &str, candidate: &str) -> bool {
    match (Version::parse(current), Version::parse(candidate)) {
        (Ok(current), Ok(candidate)) => {
            candidate.pre.is_empty() && candidate.build.is_empty() && candidate > current
        }
        _ => false,
    }
}
fn valid_download(current: &str, version: &str, url: &Url) -> bool {
    newer_stable(current, version)
        && url.as_str()
            == format!(
                "{}/{}/{version}/KanbanGit-{version}-{}.app.tar.gz",
                source().base_url,
                target(),
                target()
            )
}
fn trusted_navigation(url: &Url) -> bool {
    url.scheme() == "tauri"
        && url.host_str() == Some("localhost")
        && url.port().is_none()
        && url.username().is_empty()
        && url.password().is_none()
}
pub fn refresh_menu(app: &AppHandle, available: bool, busy: bool) {
    if let Some(menu) = app
        .menu()
        .and_then(|menu| menu.get("app-menu"))
        .and_then(|item| {
            item.as_submenu()
                .and_then(|menu| menu.get("install-update"))
        })
    {
        if let Some(item) = menu.as_menuitem() {
            let _ = item.set_enabled(available && !busy);
        }
    }
}
pub fn refresh(app: &AppHandle) {
    let (view, available, busy) = {
        let state = app.state::<Mutex<State>>();
        let state = state.lock().unwrap();
        (state.view.clone(), state.update.is_some(), state.busy())
    };
    refresh_menu(app, available, busy);
    if let Some(window) = app.get_webview_window("updates") {
        if let Ok(json) = serde_json::to_string(&view) {
            let _ = window.eval(format!("window.updateStatus?.({json})"));
        }
    }
    if let Some(window) = app.get_webview_window("launcher") {
        let _ = window.eval(format!("window.updateAvailable?.({available})"));
    }
}
pub fn show(app: &AppHandle) {
    if let Some(window) = app.get_webview_window("updates") {
        let _ = window.show();
        let _ = window.set_focus();
    }
    refresh(app);
}
fn fail(app: &AppHandle, message: &'static str) {
    {
        let state = app.state::<Mutex<State>>();
        let mut state = state.lock().unwrap();
        state.view.phase = "error";
        state.view.error = Some(message);
    }
    refresh(app);
}
fn update_error(error: &tauri_plugin_updater::Error) -> &'static str {
    use tauri_plugin_updater::Error;
    match error {
        Error::Minisign(_)
        | Error::Base64(_)
        | Error::SignatureUtf8(_)
        | Error::SignedVersionMismatch { .. }
        | Error::MissingSignedVersion => "signatureError",
        Error::Serialization(_)
        | Error::Semver(_)
        | Error::TargetsNotFound(_)
        | Error::TargetNotFound(_) => "metadataError",
        _ => "networkError",
    }
}
pub fn check(app: &AppHandle, manual: bool) {
    if manual {
        show(app);
    }
    let begin = app
        .state::<Mutex<State>>()
        .lock()
        .unwrap()
        .begin_check(manual, Instant::now());
    if !begin {
        return;
    }
    refresh(app);
    let app = app.clone();
    tauri::async_runtime::spawn(async move {
        let result = async {
            app.updater_builder()
                .pubkey(&source().public_key)
                .endpoints(vec![feed_url()])?
                .timeout(Duration::from_secs(60))
                .configure_client(|client| client.https_only(true))
                .version_comparator(|current, release| {
                    newer_stable(&current.to_string(), &release.version.to_string())
                })
                .build()?
                .check()
                .await
        }
        .await;
        match result {
            Ok(Some(mut update)) => {
                if !valid_download(
                    &update.current_version,
                    &update.version,
                    &update.download_url,
                ) || update.signature.trim().is_empty()
                {
                    fail(&app, "metadataError");
                    return;
                }
                update.timeout = Some(Duration::from_secs(600));
                let state = app.state::<Mutex<State>>();
                let mut state = state.lock().unwrap();
                state.view.phase = "available";
                state.view.version = Some(update.version.clone());
                state.view.notes = update.body.clone();
                state.update = Some(update);
            }
            Ok(None) => app.state::<Mutex<State>>().lock().unwrap().view.phase = "current",
            Err(error) => {
                fail(&app, update_error(&error));
                return;
            }
        }
        refresh(&app);
    });
}
fn command(program: &str, args: &[&str]) -> Result<String, &'static str> {
    let output = std::process::Command::new(program)
        .args(args)
        .output()
        .map_err(|_| "verificationError")?;
    if !output.status.success() {
        return Err("verificationError");
    }
    Ok(String::from_utf8_lossy(&output.stdout).trim().to_owned())
}
fn matches_architecture(header: &[u8]) -> bool {
    let expected_cpu: u32 = if cfg!(target_arch = "aarch64") {
        0x0100_000c
    } else {
        0x0100_0007
    };
    header.len() >= 8
        && header[..4] == [0xcf, 0xfa, 0xed, 0xfe]
        && header[4..8] == expected_cpu.to_le_bytes()
}
fn verify_bundle(archive: &Path, directory: &Path, version: &str) -> Result<(), &'static str> {
    command(
        "/usr/bin/tar",
        &[
            "-xzf",
            archive.to_str().ok_or("verificationError")?,
            "-C",
            directory.to_str().ok_or("verificationError")?,
        ],
    )?;
    let app = directory.join("KanbanGit.app");
    let plist = app.join("Contents/Info.plist");
    let plist = plist.to_str().ok_or("verificationError")?;
    for (field, expected) in [
        ("CFBundleShortVersionString", version),
        ("CFBundleIdentifier", "de.kanbangit.desktop"),
    ] {
        if command(
            "/usr/bin/plutil",
            &["-extract", field, "raw", "-o", "-", plist],
        )? != expected
        {
            return Err("verificationError");
        }
    }
    let executable = app.join("Contents/MacOS/kanbangit-native");
    let mut header = [0u8; 8];
    fs::File::open(executable)
        .and_then(|mut file| file.read_exact(&mut header))
        .map_err(|_| "verificationError")?;
    if !matches_architecture(&header) {
        return Err("verificationError");
    }
    command("/usr/bin/codesign", &["--verify", "--deep", "--strict", "-R", "=anchor apple generic and identifier \"de.kanbangit.desktop\" and certificate leaf[subject.OU] = \"ZZX2KZGTHU\" and certificate leaf[field.1.2.840.113635.100.6.1.13] exists", app.to_str().ok_or("verificationError")?])?;
    Ok(())
}
fn install(app: &AppHandle, confirmed_version: Option<&str>) {
    let update = {
        let state = app.state::<Mutex<State>>();
        let mut state = state.lock().unwrap();
        if state.busy() {
            return;
        }
        let Some(update) = state.update.clone() else {
            return;
        };
        if confirmed_version != Some(update.version.as_str()) {
            return;
        }
        state.view.phase = "downloading";
        state.view.error = None;
        state.view.downloaded = 0;
        state.view.total = None;
        update
    };
    refresh(app);
    let app = app.clone();
    tauri::async_runtime::spawn(async move {
        let bytes = update
            .download(
                |chunk, total| {
                    {
                        let state = app.state::<Mutex<State>>();
                        let mut state = state.lock().unwrap();
                        state.view.downloaded += chunk as u64;
                        state.view.total = total;
                    }
                    refresh(&app);
                },
                || {
                    app.state::<Mutex<State>>().lock().unwrap().view.phase = "verifying";
                    refresh(&app);
                },
            )
            .await;
        let bytes = match bytes {
            Ok(bytes) => bytes,
            Err(error) => {
                fail(&app, update_error(&error));
                return;
            }
        };
        let handle = app.clone();
        let result = tauri::async_runtime::spawn_blocking(move || -> Result<(), &'static str> {
            let cache = handle
                .path()
                .app_cache_dir()
                .map_err(|_| "installationError")?
                .join("verified-update");
            if cache.exists() {
                fs::remove_dir_all(&cache).map_err(|_| "installationError")?;
            }
            fs::create_dir_all(&cache).map_err(|_| "installationError")?;
            let archive = cache.join("update.tar.gz");
            let result = (|| {
                fs::write(&archive, &bytes).map_err(|_| "installationError")?;
                verify_bundle(&archive, &cache, &update.version)?;
                handle.state::<Mutex<State>>().lock().unwrap().view.phase = "installing";
                refresh(&handle);
                update.install(&bytes).map_err(|_| "installationError")
            })();
            let _ = fs::remove_dir_all(cache);
            result
        })
        .await;
        match result {
            Ok(Ok(())) => {
                app.state::<Mutex<State>>().lock().unwrap().view.phase = "restarting";
                refresh(&app);
                app.restart();
            }
            Ok(Err(message)) => fail(&app, message),
            Err(_) => fail(&app, "installationError"),
        }
    });
}
fn action(app: &AppHandle, url: &Url) {
    match url.path() {
        "/updates/check" => check(app, true),
        "/updates/install" => install(
            app,
            url.query_pairs()
                .find(|(key, _)| key == "version")
                .as_ref()
                .map(|(_, value)| value.as_ref()),
        ),
        "/updates/preferences" => {
            let params: std::collections::HashMap<_, _> = url.query_pairs().collect();
            let preferences = Preferences {
                automatic: params.get("automatic").is_some_and(|v| v == "true"),
                interval_hours: params
                    .get("interval")
                    .and_then(|v| v.parse().ok())
                    .unwrap_or(0),
            };
            if !preferences.valid() {
                fail(app, "preferencesError");
                return;
            }
            let saved = (|| -> Result<(), Box<dyn std::error::Error>> {
                let directory = app.path().app_config_dir()?;
                fs::create_dir_all(&directory)?;
                let pending = directory.join("update-preferences.pending");
                fs::write(&pending, serde_json::to_vec(&preferences)?)?;
                fs::rename(pending, directory.join("update-preferences.json"))?;
                Ok(())
            })();
            if saved.is_err() {
                fail(app, "preferencesError");
                return;
            }
            app.state::<Mutex<State>>().lock().unwrap().view.preferences = preferences;
            refresh(app);
        }
        _ => {}
    }
}
pub fn setup(app: &AppHandle) -> tauri::Result<()> {
    app.plugin(
        tauri_plugin_updater::Builder::new()
            .pubkey(&source().public_key)
            .build(),
    )?;
    let path = app.path().app_config_dir()?.join("update-preferences.json");
    let (preferences, error) = match fs::read(path) {
        Ok(bytes) => match serde_json::from_slice::<Preferences>(&bytes) {
            Ok(p) if p.valid() => (p, None),
            _ => (
                Preferences {
                    automatic: false,
                    ..Default::default()
                },
                Some("preferencesError"),
            ),
        },
        Err(error) if error.kind() == std::io::ErrorKind::NotFound => {
            (Preferences::default(), None)
        }
        Err(_) => (
            Preferences {
                automatic: false,
                ..Default::default()
            },
            Some("preferencesError"),
        ),
    };
    app.manage(Mutex::new(State {
        view: View {
            phase: if error.is_some() { "error" } else { "idle" },
            current_version: app.package_info().version.to_string(),
            build: crate::metadata::build_number().into(),
            version: None,
            notes: None,
            downloaded: 0,
            total: None,
            error,
            preferences,
        },
        update: None,
        last_check: None,
    }));
    let handle = app.clone();
    let window = WebviewWindowBuilder::new(app, "updates", WebviewUrl::App("updates.html".into()))
        .title(crate::locale::en::UPDATES)
        .inner_size(560.0, 690.0)
        .min_inner_size(420.0, 580.0)
        .center()
        .visible(false)
        .on_navigation(move |url| {
            if !trusted_navigation(url) {
                return false;
            }
            if url.path().starts_with("/updates/") {
                action(&handle, url);
                return false;
            }
            url.path() == "/updates.html"
        })
        .on_new_window(|_, _| NewWindowResponse::Deny)
        .on_page_load(|window, payload| {
            if payload.event() == PageLoadEvent::Finished {
                refresh(window.app_handle());
            }
        })
        .build()?;
    let hide = window.clone();
    window.on_window_event(move |event| {
        if let tauri::WindowEvent::CloseRequested { api, .. } = event {
            api.prevent_close();
            let _ = hide.hide();
        }
    });
    let handle = app.clone();
    std::thread::spawn(move || loop {
        check(&handle, false);
        std::thread::sleep(Duration::from_secs(30));
    });
    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    fn state() -> State {
        State {
            view: View {
                phase: "idle",
                current_version: "1.0.0".into(),
                build: "1".into(),
                version: None,
                notes: None,
                downloaded: 0,
                total: None,
                error: None,
                preferences: Preferences::default(),
            },
            update: None,
            last_check: None,
        }
    }
    #[test]
    fn accepts_only_newer_stable_versions_and_exact_release_paths() {
        assert!(newer_stable("1.9.9", "1.10.0"));
        for version in ["0.9.0", "1.0.0", "1.2.0-beta", "1.2.0+build", "invalid"] {
            assert!(!newer_stable("1.0.0", version));
        }
        let good = format!(
            "{}/{}/1.1.0/KanbanGit-1.1.0-{}.app.tar.gz",
            source().base_url,
            target(),
            target()
        );
        assert!(valid_download(
            "1.0.0",
            "1.1.0",
            &Url::parse(&good).unwrap()
        ));
        for input in [
            good.replace("https:", "http:"),
            good.replace(".app.tar.gz", ".dmg"),
            good.replace("1.1.0/", "0.9.0/"),
            good.replace(&target(), "foreign-apple-darwin"),
            format!("{good}?token=anything"),
            format!("{good}#fragment"),
            good.replace("https://", "https://user@"),
            "https://untrusted.example/update.app.tar.gz".into(),
        ] {
            assert!(!valid_download(
                "1.0.0",
                "1.1.0",
                &Url::parse(&input).unwrap()
            ));
        }
    }
    #[test]
    fn automatic_checks_start_once_then_respect_interval_and_opt_out() {
        let mut state = state();
        let now = Instant::now();
        assert!(state.begin_check(false, now));
        assert!(!state.begin_check(false, now));
        state.view.phase = "current";
        assert!(!state.begin_check(false, now + Duration::from_secs(6 * 3600 - 1)));
        assert!(state.begin_check(false, now + Duration::from_secs(6 * 3600)));
        state.view.phase = "current";
        state.view.preferences.automatic = false;
        assert!(!state.begin_check(false, now + Duration::from_secs(24 * 3600)));
        assert!(state.begin_check(true, now + Duration::from_secs(24 * 3600)));
    }
    #[test]
    fn manual_checks_retry_errors_but_never_overlap_downloads_or_installation() {
        let mut state = state();
        state.view.phase = "error";
        state.view.error = Some("networkError");
        assert!(state.begin_check(true, Instant::now()));
        assert!(state.view.error.is_none());
        for phase in [
            "checking",
            "downloading",
            "verifying",
            "installing",
            "restarting",
        ] {
            state.view.phase = phase;
            assert!(!state.begin_check(true, Instant::now()));
        }
    }
    #[test]
    fn preferences_validate_and_round_trip_without_server_settings() {
        let p = Preferences {
            automatic: false,
            interval_hours: 24,
        };
        let json = serde_json::to_string(&p).unwrap();
        let loaded: Preferences = serde_json::from_str(&json).unwrap();
        assert!(!loaded.automatic);
        assert_eq!(loaded.interval_hours, 24);
        assert!(loaded.valid());
        for interval in [0, 2, 100, u64::MAX] {
            assert!(!Preferences {
                automatic: true,
                interval_hours: interval
            }
            .valid());
        }
    }
    #[test]
    fn update_actions_are_confined_to_the_local_trusted_window() {
        assert!(trusted_navigation(
            &Url::parse("tauri://localhost/updates/install").unwrap()
        ));
        for address in [
            "https://kanbangit.de/updates/install",
            "https://localhost/updates/install",
            "tauri://user@localhost/updates/install",
            "tauri://localhost:443/updates/install",
            "tauri://other/updates/install",
        ] {
            assert!(!trusted_navigation(&Url::parse(address).unwrap()));
        }
    }
    #[test]
    fn rejects_foreign_or_invalid_mach_o_headers_without_developer_tools() {
        let cpu: u32 = if cfg!(target_arch = "aarch64") {
            0x0100_000c
        } else {
            0x0100_0007
        };
        let mut header = vec![0xcf, 0xfa, 0xed, 0xfe];
        header.extend(cpu.to_le_bytes());
        assert!(matches_architecture(&header));
        header[4] ^= 1;
        assert!(!matches_architecture(&header));
        assert!(!matches_architecture(b"MZ"));
        assert!(!matches_architecture(&[0; 8]));
    }
    #[test]
    fn error_categories_offer_specific_retryable_messages() {
        use tauri_plugin_updater::Error;
        assert_eq!(
            update_error(&Error::Network("offline".into())),
            "networkError"
        );
        assert_eq!(
            update_error(&Error::TargetNotFound("darwin-other".into())),
            "metadataError"
        );
        assert_eq!(
            update_error(&Error::SignatureUtf8("invalid".into())),
            "signatureError"
        );
    }
}

#[cfg(test)]
mod signed_upgrade_test {
    use super::*;
    use std::{io::Write, net::TcpListener};

    #[test]
    #[ignore = "Requires KANBANGIT_UPGRADE_BASE and KANBANGIT_UPGRADE_ARCHIVE pointing to two Developer-ID-signed macOS versions"]
    fn installs_a_real_signed_upgrade_and_rejects_tampering() {
        let base = std::env::var("KANBANGIT_UPGRADE_BASE").expect("Set the signed base app path");
        let archive = std::env::var("KANBANGIT_UPGRADE_ARCHIVE")
            .expect("Set the signed updater archive path");
        let base_version = env!("CARGO_PKG_VERSION");
        let mut next_version = Version::parse(base_version).unwrap();
        next_version.patch += 1;
        let candidate_version =
            std::env::var("KANBANGIT_UPGRADE_VERSION").unwrap_or_else(|_| next_version.to_string());
        assert!(newer_stable(base_version, &candidate_version));
        let root = std::env::temp_dir().join(format!("kanbangit-upgrade-{}", std::process::id()));
        fs::create_dir(&root).unwrap();
        struct Cleanup(std::path::PathBuf);
        impl Drop for Cleanup {
            fn drop(&mut self) {
                let _ = fs::remove_dir_all(&self.0);
            }
        }
        let _cleanup = Cleanup(root.clone());
        let installed = root.join("KanbanGit.app");
        command("/usr/bin/ditto", &[&base, installed.to_str().unwrap()]).unwrap();
        let data = root.join("user-data");
        fs::create_dir(&data).unwrap();
        fs::write(data.join("active-server"), "https://workspace.example/").unwrap();
        fs::write(data.join("session"), "existing-session").unwrap();
        let bytes = fs::read(&archive).unwrap();
        let signature = fs::read_to_string(format!("{archive}.sig")).unwrap();
        let verify_dir = root.join("verify");
        fs::create_dir(&verify_dir).unwrap();
        verify_bundle(Path::new(&archive), &verify_dir, &candidate_version).unwrap();
        assert!(verify_bundle(Path::new(&archive), &verify_dir, base_version).is_err());
        let listener = TcpListener::bind("127.0.0.1:0").unwrap();
        let address = listener.local_addr().unwrap();
        let download = bytes.clone();
        let announced_version = candidate_version.clone();
        let server = std::thread::spawn(move || {
            for index in 0..3 {
                let (mut stream, _) = listener.accept().unwrap();
                stream
                    .set_read_timeout(Some(Duration::from_secs(10)))
                    .unwrap();
                let mut request = [0; 4096];
                let _ = stream.read(&mut request).unwrap();
                let body = if index == 0 {
                    serde_json::to_vec(&serde_json::json!({"version":announced_version, "platforms":{(format!("darwin-{}", std::env::consts::ARCH)): {"url":format!("http://{address}/update.tar.gz"), "signature":signature.trim()}}})).unwrap()
                } else if index == 1 {
                    b"tampered update".to_vec()
                } else {
                    download.clone()
                };
                write!(
                    stream,
                    "HTTP/1.1 200 OK\r\nContent-Length: {}\r\nConnection: close\r\n\r\n",
                    body.len()
                )
                .unwrap();
                stream.write_all(&body).unwrap();
            }
        });
        let mut context = crate::desktop::context();
        context.config_mut().plugins.0.insert("updater".into(), serde_json::json!({"pubkey":source().public_key, "dangerousInsecureTransportProtocol":true}));
        let app = tauri::test::mock_builder()
            .plugin(tauri_plugin_updater::Builder::new().build())
            .build(context)
            .unwrap();
        let update = tauri::async_runtime::block_on(async {
            app.updater_builder()
                .executable_path(installed.join("Contents/MacOS/kanbangit-native"))
                .endpoints(vec![
                    Url::parse(&format!("http://{address}/latest.json")).unwrap()
                ])
                .unwrap()
                .timeout(Duration::from_secs(20))
                .build()
                .unwrap()
                .check()
                .await
                .unwrap()
                .unwrap()
        });
        assert_eq!(update.current_version, base_version);
        let rejected =
            tauri::async_runtime::block_on(update.download(|_, _| {}, || {})).unwrap_err();
        assert_eq!(update_error(&rejected), "signatureError");
        let plist = installed.join("Contents/Info.plist");
        assert_eq!(
            command(
                "/usr/bin/plutil",
                &[
                    "-extract",
                    "CFBundleShortVersionString",
                    "raw",
                    "-o",
                    "-",
                    plist.to_str().unwrap()
                ]
            )
            .unwrap(),
            base_version
        );
        let verified = tauri::async_runtime::block_on(update.download(|_, _| {}, || {})).unwrap();
        assert_eq!(verified, bytes);
        update.install(verified).unwrap();
        assert_eq!(
            command(
                "/usr/bin/plutil",
                &[
                    "-extract",
                    "CFBundleShortVersionString",
                    "raw",
                    "-o",
                    "-",
                    plist.to_str().unwrap()
                ]
            )
            .unwrap(),
            candidate_version
        );
        command(
            "/usr/bin/codesign",
            &[
                "--verify",
                "--deep",
                "--strict",
                installed.to_str().unwrap(),
            ],
        )
        .unwrap();
        assert_eq!(
            fs::read_to_string(data.join("active-server")).unwrap(),
            "https://workspace.example/"
        );
        assert_eq!(
            fs::read_to_string(data.join("session")).unwrap(),
            "existing-session"
        );
        server.join().unwrap();
    }
}