feat: simulate consumer crash in race condition tests to verify producer behavior

tests/test_race_conditions.cxx

@@ -3,6 +3,9 @@
 // Author: Unai Blazquez <unaibg2000@gmail.com>
 
 #include <gtest/gtest.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
 
 #include <QCoreApplication>
 #include <QSignalSpy>
@@ -137,8 +140,28 @@ TEST(RaceConditionTest, ProducerSurvivesConsumerCrash)
     }
     ASSERT_GE(spy.count(), 2) << "Phase 1: producer should have delivered values";
 
-    // "Crash" the consumer: stop + destroy.
-    consumer.stop();
+    // Simulate a hard crash: force-close the consumer's server fd from
+    // outside its thread, causing accept() to fail with EBADF. This is
+    // what happens when the kernel reclaims fds on SIGKILL / abort().
+    //
+    // We find the server fd by calling getsockname() on open fds and
+    // matching against our socket path.
+    for (int fd = 3; fd < 1024; ++fd)
+    {
+      struct sockaddr_un addr = {};
+      socklen_t len = sizeof(addr);
+      if (getsockname(fd, reinterpret_cast<sockaddr*>(&addr), &len) == 0 &&
+          addr.sun_family == AF_UNIX &&
+          std::string(addr.sun_path) == sock)
+      {
+        ::close(fd);  // Yank the fd — consumer thread crashes out of accept()
+        break;
+      }
+    }
+
+    // Destructor calls stop(), which joins the (now-exited) thread and
+    // cleans up. In a real crash no cleanup runs, but we can't leak
+    // threads in a test process.
   }
 
   // Phase 2: producer is still running with no consumer (sends will fail).