FlowTask

// ── S01 Step 9-15: register ───────────────────────
#[tauri::command]
async fn register(
    params: RegisterParams,
    pool: tauri::State<'_, SqlitePool>,
) -> CmdResult<UserSession> {
    let row = sqlx::query("SELECT COUNT(*) as count FROM users WHERE username = ?")
        .bind(&params.username).fetch_one(pool.inner()).await
        .map_err(|_| CommandError::new("DB_ERROR", "Query failed"))?;
    if row.get::<i64, _>("count") > 0 {
        return Err(CommandError::new("USERNAME_EXISTS", "Username taken"));
    }
    let pw_hash = hash(&params.password, DEFAULT_COST)
        .map_err(|_| CommandError::new("HASH_ERROR", "Hash failed"))?;
    let result = sqlx::query("INSERT INTO users (username, password) VALUES (?, ?)")
        .bind(&params.username).bind(&pw_hash)
        .execute(pool.inner()).await
        .map_err(|_| CommandError::new("DB_WRITE_ERROR", "Write failed"))?;
    Ok(UserSession {
        user_id: result.last_insert_rowid(),
        username: params.username,
        tasks: vec![], categories: vec![],
    })
}

#[tokio::test]
async fn ot_s01_01_register_success() {
    let pool = setup_db().await;
    let session = cmd_register("xiaoli".into(), "Pass1234".into(), &pool)
        .await.expect("register should succeed");
    assert_eq!(session.username, "xiaoli");
    assert!(session.user_id > 0);
    assert!(session.tasks.is_empty());
}

#[tokio::test]
async fn ot_s01_02_register_username_exists() {
    let pool = setup_db().await;
    cmd_register("xiaoli".into(), "Pass1234".into(), &pool).await.unwrap();
    let err = cmd_register("xiaoli".into(), "Other123".into(), &pool)
        .await.expect_err("duplicate should fail");
    assert_eq!(err.code, "USERNAME_EXISTS");
}