implemented Producer API and header, stub and tests. Builds cleanly, tests fail for now

include/Producer.hpp

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+#pragma once
+// Producer.hpp
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Author: Unai Blazquez <unaibg2000@gmail.com>
+#include <atomic>
+#include <chrono>
+#include <functional>
+#include <thread>
+
+#include "SysfsRead.hpp"
+
+using RandomFn = std::function<int()>;
+using SleepFn = std::function<void(std::chrono::milliseconds)>;
+class Producer
+{
+ public:
+  /// @brief Construct a Producer bound to a sysfs-like control file.
+  /// @param sysfs_path Path to the control file (e.g. "./fake_sysfs_input").
+  /// @param send_fn    Function called whenever a new integer should be sent.
+  /// @param sleep_fn   Stub for sleeping function, allows reducing sleep on
+  /// testing
+  Producer(const std::filesystem::path& sysfs_path,
+           std::function<void(int)> send_fn, RandomFn random_fn,
+           SleepFn sleep_fn = default_sleep);
+
+  /// @brief Start the worker thread. Safe to call only once.
+  void start();
+
+  /// @brief Request the worker thread to stop and wait for it to finish.
+  void stop();
+
+ private:
+  /// @brief Main loop executed by the worker thread.
+  void run_loop();
+
+  std::thread m_thread;
+  std::atomic<bool> m_running;
+  SysfsReader m_reader;
+  RandomFn m_random;
+  SleepFn m_sleep;
+  static void default_sleep(std::chrono::milliseconds d)
+  {
+    std::this_thread::sleep_for(d);
+  }
+  std::function<void(int)> m_send;
+};