tests/test_race_conditions.cxx

@@ -5,13 +5,17 @@
 #include <gtest/gtest.h>
 
 #include <QCoreApplication>
+#include <QSignalSpy>
 #include <atomic>
 #include <chrono>
+#include <fstream>
 #include <iostream>
 #include <stdexcept>
 #include <thread>
+#include <vector>
 
 #include "Consumer.hpp"
+#include "Producer.hpp"
 #include "UnixIpcBridge.hpp"
 
 static int argc_ = 0;
@@ -39,9 +43,6 @@ TEST(RaceConditionTest, RepeatedStartStopWhileProducerSends)
     }
   });
 
-  // Producer thread: keeps trying to send values. connect() failures
-  // (consumer mid-restart) are expected and silently ignored.
-  
   std::atomic<bool> producer_running{true};
   std::thread producer([&]() {
     while (producer_running.load())
@@ -59,7 +60,6 @@ TEST(RaceConditionTest, RepeatedStartStopWhileProducerSends)
     }
   });
 
-  // Main thread: repeatedly start/stop the consumer.
   for (int i = 0; i < kCycles; ++i)
   {
     ConsumerThread consumer(sock);
@@ -81,3 +81,97 @@ TEST(RaceConditionTest, RepeatedStartStopWhileProducerSends)
   // If we reach here, no deadlock across kCycles start/stop cycles.
   SUCCEED();
 }
+
+TEST(RaceConditionTest, ProducerSurvivesConsumerCrash)
+{
+  const std::string sock = "/tmp/test_crash.sock";
+  const std::string sysfs = "./fake_sysfs_race";
+
+  // Prepare sysfs file so the producer is in Enabled state.
+  { std::ofstream(sysfs) << "1\n"; }
+
+  // Track what the producer sends.
+  std::vector<int> sent_values;
+  std::mutex sent_mutex;
+  std::vector<std::string> logs;
+  std::mutex log_mutex;
+
+  auto make_safe_send = [&](const std::string& path) {
+    return [&, path](int value) {
+      try
+      {
+        UnixIpcBridge bridge(path);
+        bridge.send(value);
+        std::lock_guard<std::mutex> lk(sent_mutex);
+        sent_values.push_back(value);
+      }
+      catch (const std::runtime_error&)
+      {
+        // Consumer is down — expected during the "crash" window.
+      }
+    };
+  };
+
+  Producer producer(
+      sysfs, make_safe_send(sock), []() { return 123; },
+      [&](const std::string& msg) {
+        std::lock_guard<std::mutex> lk(log_mutex);
+        logs.push_back(msg);
+      },
+      [](std::chrono::milliseconds) {
+        // Use a short sleep so the test runs fast.
+        std::this_thread::sleep_for(std::chrono::milliseconds(20));
+      });
+
+  // Phase 1: start consumer, start producer, let a few values flow.
+  {
+    ConsumerThread consumer(sock);
+    QSignalSpy spy(&consumer, &ConsumerThread::valueReceived);
+    consumer.start();
+    producer.start();
+
+    // Wait for at least 2 values to arrive.
+    for (int attempt = 0; spy.count() < 2 && attempt < 50; ++attempt)
+    {
+      spy.wait(100);
+    }
+    ASSERT_GE(spy.count(), 2) << "Phase 1: producer should have delivered values";
+
+    // "Crash" the consumer: stop + destroy.
+    consumer.stop();
+  }
+
+  // Phase 2: producer is still running with no consumer (sends will fail).
+  std::this_thread::sleep_for(std::chrono::milliseconds(200));
+
+  // Phase 3: bring up a fresh consumer. Producer should resume delivering.
+  {
+    ConsumerThread consumer2(sock);
+    QSignalSpy spy2(&consumer2, &ConsumerThread::valueReceived);
+    consumer2.start();
+
+    for (int attempt = 0; spy2.count() < 2 && attempt < 50; ++attempt)
+    {
+      spy2.wait(100);
+    }
+
+    consumer2.stop();
+
+    ASSERT_GE(spy2.count(), 2)
+        << "Phase 3: producer must deliver to a new consumer after crash";
+
+    // Values received by the second consumer should all be 123.
+    for (int i = 0; i < spy2.count(); ++i)
+    {
+      EXPECT_EQ(spy2.at(i).at(0).toInt(), 123);
+    }
+  }
+
+  producer.stop();
+
+  // Producer logged throughout all three phases.
+  {
+    std::lock_guard<std::mutex> lk(log_mutex);
+    EXPECT_GE(logs.size(), 3u) << "Producer should have kept logging";
+  }
+}