seshcookie 0.1.0

Stateless, encrypted, type-safe session cookies for Rust web applications.
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//! Full-stack integration tests for the seshcookie-rs Axum extractor.
//!
//! These tests drive an `axum::Router` directly via `tower::ServiceExt::oneshot`
//! so no real network is involved. The acceptance-criteria identifiers
//! (`seshcookie-rs.AC5.1`-`AC5.5`, `seshcookie-rs.AC9.2`-`AC9.3`) appear in
//! the test names so the AC -> test mapping is traceable.
//!
//! AC9.3 requires the entire test suite to run on a multi-threaded tokio
//! runtime with at least 4 worker threads. Every `#[tokio::test]` annotation
//! in this file uses `flavor = "multi_thread", worker_threads = 4`. The
//! self-auditing test `axum_all_integration_tests_run_on_multi_thread_runtime_seshcookie_rs_ac9_3`
//! reads the file and asserts no bare `#[tokio::test]` annotations remain.
//!
//! Cookies for the AC9.2 100-concurrent-request test are constructed via
//! `seshcookie::__testing::encode_cookie_for_layer`, an explicitly
//! `#[doc(hidden)]` helper that lets integration tests build cookie values
//! without re-implementing the AEAD pipeline. The helper is not part of the
//! public API contract.

use std::sync::Arc;
use std::time::SystemTime;

use axum::{
    Router,
    body::Body,
    routing::{get, post},
};
use http::{Request, StatusCode, header::SET_COOKIE};
use http_body_util::BodyExt;
use serde::{Deserialize, Serialize};
use seshcookie::{Session, SessionConfig, SessionKeys, SessionLayer};
use tokio::sync::Mutex;
use tower::ServiceExt;

/// Primary session payload used across the suite. Mirrors the shape an
/// application would store: a numeric user id plus a textual role.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
struct AppSession {
    user_id: u64,
    role: String,
}

/// Secondary session payload used by the AC5.2 two-layers test. A distinct
/// type plus a distinct cookie name lets two `SessionLayer`s coexist on the
/// same router.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
struct AppSessionB {
    page: u32,
}

fn build_keys() -> SessionKeys {
    SessionKeys::new(b"fedcba9876543210fedcba9876543210").expect("32-byte key is valid")
}

fn build_layer() -> SessionLayer<AppSession> {
    // `secure(false)` lets the test request reach the handler over plain HTTP
    // (not strictly required when using oneshot, but matches the example's
    // posture). The default 24h max_age means the AC9.2 cookies stay valid
    // for the duration of the test.
    let config = SessionConfig::default().secure(false);
    SessionLayer::<AppSession>::new(build_keys(), config).expect("layer construction succeeds")
}

fn build_app() -> Router {
    Router::new()
        .route("/insert", post(insert_handler))
        .route("/get", get(get_handler))
        .route("/optional", get(optional_handler))
        .route("/required", get(required_handler))
        .route("/two-handles", get(two_handles_handler))
        .layer(build_layer())
}

async fn insert_handler(session: Session<AppSession>) -> &'static str {
    session
        .insert(AppSession {
            user_id: 1,
            role: "admin".into(),
        })
        .await;
    "inserted"
}

async fn get_handler(session: Session<AppSession>) -> String {
    match session.get().await {
        Some(s) => format!("{}:{}", s.user_id, s.role),
        None => "none".into(),
    }
}

async fn optional_handler(session: Option<Session<AppSession>>) -> &'static str {
    if session.is_some() { "some" } else { "none" }
}

async fn required_handler(_session: Session<AppSession>) -> &'static str {
    "required-ok"
}

async fn two_handles_handler(s1: Session<AppSession>, s2: Session<AppSession>) -> String {
    s1.insert(AppSession {
        user_id: 99,
        role: "q".into(),
    })
    .await;
    let seen = s2.get().await.expect("s2 must observe s1's insert");
    format!("{}:{}", seen.user_id, seen.role)
}

/// Read a response body to a `String` for assertions. Integration tests use
/// `String` rather than `Bytes` because every response in this suite is
/// plain UTF-8 text.
async fn body_text(response: http::Response<Body>) -> String {
    let bytes = response
        .into_body()
        .collect()
        .await
        .expect("collecting an in-memory body never fails")
        .to_bytes();
    String::from_utf8(bytes.to_vec()).expect("test handlers all produce UTF-8")
}

/// Extract the first `Set-Cookie` header value from a response. The
/// integration tests target single-cookie responses; if that ever changes,
/// update callers to be explicit about which cookie they want.
fn first_set_cookie(response: &http::Response<Body>) -> String {
    response
        .headers()
        .get(SET_COOKIE)
        .expect("response carries a Set-Cookie header")
        .to_str()
        .expect("Set-Cookie value is ASCII")
        .to_string()
}

/// Extract the `name=value` portion of a `Set-Cookie` header. The remainder
/// (Path, HttpOnly, ...) is dropped — only the name=value pair is sent on
/// subsequent requests.
fn cookie_name_value(set_cookie: &str) -> String {
    set_cookie
        .split(';')
        .next()
        .expect("Set-Cookie always has at least name=value")
        .to_string()
}

// --- AC5.4: handler without layer returns HTTP 500 -------------------------

/// seshcookie-rs.AC5.4: a required `Session<T>` extractor on a handler that
/// has no `SessionLayer<T>` mounted produces an HTTP 500 with a body that
/// describes the misconfiguration. The router has no layer at all, so the
/// extension lookup misses and the rejection's `IntoResponse` runs.
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn axum_handler_without_layer_returns_http_500_seshcookie_rs_ac5_4() {
    let app: Router = Router::new().route("/required", get(required_handler));

    let req = Request::builder()
        .method("GET")
        .uri("/required")
        .body(Body::empty())
        .expect("test request is well-formed");

    let response = app.oneshot(req).await.expect("oneshot delivers a response");

    assert_eq!(response.status(), StatusCode::INTERNAL_SERVER_ERROR);

    let body = body_text(response).await;
    assert!(
        body.contains("not mounted"),
        "AC5.4 response body must mention the missing layer; got {body:?}"
    );
}

// --- AC5.1: required extractor succeeds, payload round-trips --------------

/// seshcookie-rs.AC5.1: with `SessionLayer<T>` mounted, the handler's
/// required `Session<T>` extractor produces a working handle. A POST to
/// `/insert` writes a payload and emits a `Set-Cookie`. A second GET to
/// `/get` carrying that cookie observes the inserted payload.
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn axum_handler_with_layer_extracts_successfully_seshcookie_rs_ac5_1() {
    let app = build_app();

    let req = Request::builder()
        .method("POST")
        .uri("/insert")
        .body(Body::empty())
        .expect("test request is well-formed");
    let response = app.clone().oneshot(req).await.expect("first call succeeds");
    assert_eq!(response.status(), StatusCode::OK);

    let set_cookie = first_set_cookie(&response);
    let cookie_pair = cookie_name_value(&set_cookie);

    let body = body_text(response).await;
    assert_eq!(body, "inserted");

    let req = Request::builder()
        .method("GET")
        .uri("/get")
        .header(http::header::COOKIE, &cookie_pair)
        .body(Body::empty())
        .expect("test request is well-formed");
    let response = app.oneshot(req).await.expect("second call succeeds");
    assert_eq!(response.status(), StatusCode::OK);

    let body = body_text(response).await;
    assert_eq!(
        body, "1:admin",
        "the cookie round-trips the inserted payload"
    );
}

// --- AC5.3: optional extractor returns None on missing layer --------------

/// seshcookie-rs.AC5.3: a handler declaring `Option<Session<T>>` on a router
/// without the matching layer sees `None` rather than producing an HTTP
/// rejection. The handler responds 200 with the literal `"none"`.
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn axum_handler_with_option_extractor_gets_none_when_layer_missing_seshcookie_rs_ac5_3() {
    let app: Router = Router::new().route("/optional", get(optional_handler));

    let req = Request::builder()
        .method("GET")
        .uri("/optional")
        .body(Body::empty())
        .expect("test request is well-formed");
    let response = app.oneshot(req).await.expect("oneshot delivers a response");

    assert_eq!(response.status(), StatusCode::OK);
    let body = body_text(response).await;
    assert_eq!(body, "none");
}

/// seshcookie-rs.AC5.3 (companion): with the layer mounted, the optional
/// extractor yields `Some(_)` even when the request carries no cookie. The
/// layer always installs an empty session handle in extensions; only the
/// payload is `None` in that case, not the handle itself.
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn axum_handler_with_option_extractor_gets_some_when_layer_present_seshcookie_rs_ac5_3() {
    let app = build_app();

    let req = Request::builder()
        .method("GET")
        .uri("/optional")
        .body(Body::empty())
        .expect("test request is well-formed");
    let response = app.oneshot(req).await.expect("oneshot delivers a response");

    assert_eq!(response.status(), StatusCode::OK);
    let body = body_text(response).await;
    assert_eq!(body, "some");
}

// --- AC5.5: two extractor handles share state inside one request ----------

/// seshcookie-rs.AC5.5: a handler that extracts `Session<T>` twice receives
/// two handles that share underlying state. A mutation through one is
/// visible through the other inside the same request.
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn axum_two_handles_share_underlying_state_seshcookie_rs_ac5_5() {
    let app = build_app();

    let req = Request::builder()
        .method("GET")
        .uri("/two-handles")
        .body(Body::empty())
        .expect("test request is well-formed");
    let response = app.oneshot(req).await.expect("oneshot delivers a response");

    assert_eq!(response.status(), StatusCode::OK);
    let body = body_text(response).await;
    assert_eq!(body, "99:q", "AC5.5 demands the two handles share state");
}

// --- AC5.2: two layers with distinct payload types coexist -----------------

async fn insert_a_handler(session: Session<AppSession>) -> &'static str {
    session
        .insert(AppSession {
            user_id: 7,
            role: "alpha".into(),
        })
        .await;
    "a"
}

async fn insert_b_handler(session: Session<AppSessionB>) -> &'static str {
    session.insert(AppSessionB { page: 42 }).await;
    "b"
}

async fn read_a_handler(session: Session<AppSession>) -> String {
    match session.get().await {
        Some(s) => format!("{}:{}", s.user_id, s.role),
        None => "none".into(),
    }
}

async fn read_b_handler(session: Session<AppSessionB>) -> String {
    match session.get().await {
        Some(s) => format!("page={}", s.page),
        None => "none".into(),
    }
}

fn build_two_layer_app() -> Router {
    let config_a = SessionConfig::default()
        .secure(false)
        .cookie_name("session_a");
    let config_b = SessionConfig::default()
        .secure(false)
        .cookie_name("session_b");
    let layer_a = SessionLayer::<AppSession>::new(build_keys(), config_a).expect("layer A");
    let layer_b = SessionLayer::<AppSessionB>::new(build_keys(), config_b).expect("layer B");

    Router::new()
        .route("/insert-a", post(insert_a_handler))
        .route("/insert-b", post(insert_b_handler))
        .route("/read-a", get(read_a_handler))
        .route("/read-b", get(read_b_handler))
        .layer(layer_a)
        .layer(layer_b)
}

/// seshcookie-rs.AC5.2: two `SessionLayer`s with distinct payload types `A`
/// and `B`, distinct cookie names (`session_a` and `session_b`), and the
/// same key material coexist on one router. Each handler sees its own
/// typed payload — no crossover.
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn axum_two_layers_with_distinct_types_coexist_seshcookie_rs_ac5_2() {
    let app = build_two_layer_app();

    // Insert into layer A.
    let req = Request::builder()
        .method("POST")
        .uri("/insert-a")
        .body(Body::empty())
        .expect("test request is well-formed");
    let response_a = app
        .clone()
        .oneshot(req)
        .await
        .expect("insert-a delivers a response");
    assert_eq!(response_a.status(), StatusCode::OK);
    let cookie_a = cookie_name_value(&first_set_cookie(&response_a));
    assert!(
        cookie_a.starts_with("session_a="),
        "layer A must emit a cookie under its configured name; got {cookie_a:?}"
    );

    // Insert into layer B.
    let req = Request::builder()
        .method("POST")
        .uri("/insert-b")
        .body(Body::empty())
        .expect("test request is well-formed");
    let response_b = app
        .clone()
        .oneshot(req)
        .await
        .expect("insert-b delivers a response");
    assert_eq!(response_b.status(), StatusCode::OK);
    let cookie_b = cookie_name_value(&first_set_cookie(&response_b));
    assert!(
        cookie_b.starts_with("session_b="),
        "layer B must emit a cookie under its configured name; got {cookie_b:?}"
    );

    // Both cookies on the third request: each handler decodes its own.
    let cookie_header = format!("{cookie_a}; {cookie_b}");

    let req = Request::builder()
        .method("GET")
        .uri("/read-a")
        .header(http::header::COOKIE, &cookie_header)
        .body(Body::empty())
        .expect("test request is well-formed");
    let response = app
        .clone()
        .oneshot(req)
        .await
        .expect("read-a delivers a response");
    assert_eq!(response.status(), StatusCode::OK);
    assert_eq!(body_text(response).await, "7:alpha");

    let req = Request::builder()
        .method("GET")
        .uri("/read-b")
        .header(http::header::COOKIE, &cookie_header)
        .body(Body::empty())
        .expect("test request is well-formed");
    let response = app.oneshot(req).await.expect("read-b delivers a response");
    assert_eq!(response.status(), StatusCode::OK);
    assert_eq!(body_text(response).await, "page=42");
}

// --- AC9.2 / AC9.3: 100 concurrent requests on multi-thread runtime -------

/// seshcookie-rs.AC9.2: 100 concurrent requests, each carrying a distinct
/// pre-encoded cookie, complete with the correct per-request payload. No
/// cross-request state bleed and no deadlock.
///
/// seshcookie-rs.AC9.3: this test runs on a multi-threaded tokio runtime
/// with 4 worker threads (matching every other test in the file). A
/// single-threaded runtime would mask `!Send` bugs; the multi-thread
/// flavor catches them at runtime.
///
/// Cookies are produced by the `__testing::encode_cookie_for_layer`
/// helper rather than the public POST/extract-cookie dance because the
/// dance would serialize 100 round-trips and ruin the concurrency test.
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn axum_100_concurrent_requests_multi_thread_runtime_seshcookie_rs_ac9_2_ac9_3() {
    let layer = build_layer();
    let app: Router = Router::new()
        .route("/get", get(get_handler))
        .layer(layer.clone());

    // Pre-compute one cookie per request so nothing in the per-task
    // critical path touches the OS RNG (the test stays focused on
    // request dispatch concurrency, not RNG contention).
    let now = SystemTime::now();
    let cookies: Vec<(u64, String)> = (0..100u64)
        .map(|i| {
            let payload = AppSession {
                user_id: i,
                role: format!("role-{i}"),
            };
            let cookie = seshcookie::__testing::encode_cookie_for_layer(&layer, &payload, now);
            (i, cookie)
        })
        .collect();

    let mut handles = Vec::with_capacity(cookies.len());
    for (id, cookie_value) in cookies {
        let app = app.clone();
        handles.push(tokio::spawn(async move {
            let req = Request::builder()
                .method("GET")
                .uri("/get")
                .header(http::header::COOKIE, format!("session={cookie_value}"))
                .body(Body::empty())
                .expect("test request is well-formed");
            let response = app.oneshot(req).await.expect("oneshot delivers a response");
            assert_eq!(
                response.status(),
                StatusCode::OK,
                "all 100 requests must succeed"
            );
            let body = body_text(response).await;
            (id, body)
        }));
    }

    for handle in handles {
        let (id, body) = handle.await.expect("task did not panic");
        let expected = format!("{id}:role-{id}");
        assert_eq!(
            body, expected,
            "request {id} must observe its own cookie's payload, no cross-request bleed"
        );
    }
}

/// seshcookie-rs.AC9.3 (self-audit): every `#[tokio::test]` annotation in
/// this file uses `flavor = "multi_thread", worker_threads = 4`. A bare
/// `#[tokio::test]` would silently slip onto a single-threaded runtime
/// and mask `!Send` regressions. This test reads the source file and
/// asserts no bare annotation remains.
///
/// The self-audit only inspects lines that *start with* the attribute
/// (after leading whitespace). Mentions of the attribute name inside
/// doc-comments or string literals — necessary to describe this very
/// rule — are skipped on purpose; an actual `#[tokio::test]` attribute
/// always sits at column 0 of its line in idiomatic Rust.
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn axum_all_integration_tests_run_on_multi_thread_runtime_seshcookie_rs_ac9_3() {
    let source = std::fs::read_to_string(file!())
        .expect("test binary can read its own source file at test time");

    let mut total_attrs = 0usize;
    let mut bare_count = 0usize;
    for line in source.lines() {
        let trimmed = line.trim_start();
        // Real attribute uses start at column 0 (leading whitespace tolerated)
        // with the literal `#[tokio::test`. Doc comments (`//!` or `///`)
        // and inline references inside string literals start with other
        // characters and are filtered out here.
        if !trimmed.starts_with("#[tokio::test") {
            continue;
        }
        total_attrs += 1;
        // Anything that is not `#[tokio::test(...)]` counts as bare.
        let after = &trimmed["#[tokio::test".len()..];
        if !after.starts_with('(') {
            bare_count += 1;
        }
    }

    assert!(
        total_attrs > 0,
        "AC9.3 self-audit must observe at least one #[tokio::test] attribute; \
         found {total_attrs} (the regex above is broken if this fires)"
    );
    assert_eq!(
        bare_count, 0,
        "AC9.3: every #[tokio::test] in tests/axum_integration.rs must use \
         flavor = \"multi_thread\", worker_threads = 4 — found {bare_count} bare attribute(s)"
    );
}

// --- Compile-time anchor: the integration suite uses tokio::sync::Mutex ---

/// Anchor an `Arc<tokio::sync::Mutex<_>>` reference at compile time so this
/// test file documents (and a future migration would have to actively
/// remove) the project's async-discipline rule. Production code in
/// `src/extract.rs` already enforces this; the integration suite carries
/// the same constraint by using the same primitive.
#[allow(dead_code)]
fn _async_discipline_anchor() -> Arc<Mutex<u8>> {
    Arc::new(Mutex::new(0))
}