Problem: no test case for ZMQ_PROBE_ROUTER on ZMQ_DEALER socket

Solution: add test case

tests/test_probe_router.cpp

@@ -76,6 +76,37 @@ void test_probe_router_router ()
     test_context_socket_close (client);
 }
 
+void test_probe_router_dealer ()
+{
+    //  Create server and bind to endpoint
+    void *server = test_context_socket (ZMQ_ROUTER);
+
+    char my_endpoint[MAX_SOCKET_STRING];
+    bind_loopback_ipv4 (server, my_endpoint, sizeof (my_endpoint));
+
+    //  Create client and connect to server, doing a probe
+    void *client = test_context_socket (ZMQ_DEALER);
+    TEST_ASSERT_SUCCESS_ERRNO (zmq_setsockopt (client, ZMQ_ROUTING_ID, "X", 1));
+    int probe = 1;
+    TEST_ASSERT_SUCCESS_ERRNO (
+      zmq_setsockopt (client, ZMQ_PROBE_ROUTER, &probe, sizeof (probe)));
+    TEST_ASSERT_SUCCESS_ERRNO (zmq_connect (client, my_endpoint));
+
+    //  We expect a routing id=X + empty message from client
+    recv_string_expect_success (server, "X", 0);
+    unsigned char buffer[255];
+    TEST_ASSERT_SUCCESS_ERRNO (zmq_recv (server, buffer, 255, 0));
+
+    //  Send a message to client now
+    send_string_expect_success (server, "X", ZMQ_SNDMORE);
+    send_string_expect_success (server, "Hello", 0);
+
+    recv_string_expect_success (client, "Hello", 0);
+
+    test_context_socket_close (server);
+    test_context_socket_close (client);
+}
+
 int main ()
 {
     setup_test_environment ();
@@ -83,6 +114,7 @@ int main ()
     UNITY_BEGIN ();
 
     RUN_TEST (test_probe_router_router);
+    RUN_TEST (test_probe_router_dealer);
 
     return UNITY_END ();
 }