Problem: no tests for monitor_t::abort

Solution: add a test and fix implementation of monitor_t::abort to make it usable

tests/monitor.cpp

@@ -2,6 +2,10 @@
 #include <gmock/gmock.h>
 #include <zmq.hpp>
 
+#ifdef ZMQ_CPP11
+#include <thread>
+#endif
+
 class mock_monitor_t : public zmq::monitor_t
 {
   public:
@@ -40,3 +44,39 @@ TEST(monitor, init_check)
     while (monitor.check_event(100)) {
     }
 }
+
+#ifdef ZMQ_CPP11
+TEST(monitor, init_abort)
+{
+    zmq::context_t ctx;
+    zmq::socket_t bind_socket(ctx, zmq::socket_type::dealer);
+
+    bind_socket.bind("tcp://127.0.0.1:*");
+    char endpoint[255];
+    size_t endpoint_len = sizeof(endpoint);
+    bind_socket.getsockopt(ZMQ_LAST_ENDPOINT, &endpoint, &endpoint_len);
+
+    zmq::socket_t connect_socket(ctx, zmq::socket_type::dealer);
+
+    mock_monitor_t monitor;
+    monitor.init(connect_socket, "inproc://foo");
+    EXPECT_CALL(monitor, on_event_connect_delayed(testing::_, testing::_))
+      .Times(testing::AtLeast(1));
+    EXPECT_CALL(monitor, on_event_connected(testing::_, testing::_))
+      .Times(testing::AtLeast(1));
+
+    auto thread = std::thread([&monitor] {
+        while (monitor.check_event(-1)) {
+        }
+    });
+
+    connect_socket.connect(endpoint);
+    std::this_thread::sleep_for(std::chrono::milliseconds(250));
+    // TODO instead of sleeping an arbitrary amount of time, we should better
+    // wait until the expectations have met. How can this be done with
+    // googlemock?
+
+    monitor.abort();
+    thread.join();
+}
+#endif

zmq.hpp

@@ -849,7 +849,7 @@ class monitor_t
 #ifdef ZMQ_EVENT_MONITOR_STOPPED
         if (event->event == ZMQ_EVENT_MONITOR_STOPPED) {
             zmq_msg_close(&eventMsg);
-            return true;
+            return false;
         }
 
 #endif
@@ -923,11 +923,7 @@ class monitor_t
         if (socketPtr)
             zmq_socket_monitor(socketPtr, NULL, 0);
 
-        if (monitor_socket)
-            zmq_close(monitor_socket);
-
         socketPtr = NULL;
-        monitor_socket = NULL;
     }
 #endif
     virtual void on_monitor_started() {}