refactoring: programmatically generate temporary file name in test

Latest gcc throws errors when using tmpnam. Generate temporary file name
within the test to work around. It has the same shortcomings as using
tmpnam, but they are no risk as it is used only in the tests.

tests/integration/WireServerTest.cpp

@@ -4,6 +4,7 @@
 
 #include <filesystem>
 #include <memory>
+#include <random>
 #include <thread>
 #include <chrono>
 
@@ -171,10 +172,7 @@ class UnixSocketServerTest : public SocketServerTest {
     std::unique_ptr<UnixSocketServer> server;
 
     virtual SocketServer* createListeningServer() {
-      char filename[L_tmpnam];
-      if (!std::tmpnam(filename)) {
-          throw std::runtime_error("unable to create name for temporary file");
-      }
+        const std::string filename = std::filesystem::temp_directory_path() / randomString();
         server.reset(new UnixSocketServer(&protocolHandler));
         server->listen(filename);
         return server.get();
@@ -183,6 +181,20 @@ class UnixSocketServerTest : public SocketServerTest {
     virtual void destroyListeningServer() {
         server.reset();
     }
+
+private:
+    std::random_device rd{};
+    std::mt19937 gen{rd()};
+    std::uniform_int_distribution<> distrib{0, 15};
+
+    std::string randomString()
+    {
+        std::stringstream out{};
+        for (std::size_t i = 0; i < 16; i++) {
+            out << std::hex << distrib(gen);
+        }
+        return out.str();
+    }
 };
 
 /*