Wait for the Close Frame in the Moonraker Status Stream Test

The fake printer counts the agent's close frame in its read handler, but
Beast answers the close before that read completes, so stop() can return
and the test can read the counter before it is incremented. On a loaded
runner the check saw 0.

Wait for the counter like the other fake-printer counters do, then keep
the exact-count check.

tests/slic3rutils/test_moonraker_printer_agent.cpp

@@ -150,6 +150,13 @@ public:
         return m_close_frames;
     }
 
+    // The printer answers a close frame before its own read completes, so the agent's stop can return first.
+    bool wait_for_close_frames(int count)
+    {
+        std::unique_lock<std::mutex> lock(m_mutex);
+        return m_changed.wait_for(lock, 10s, [&] { return m_close_frames >= count; });
+    }
+
     // Hangs up every connection that is waiting.
     void release()
     {
@@ -277,6 +284,7 @@ private:
                 if (ec == websocket::error::closed) {
                     std::lock_guard<std::mutex> lock(m_mutex);
                     ++m_close_frames;
+                    m_changed.notify_all();
                 }
                 if (ec)
                     reading = false;
@@ -449,6 +457,7 @@ TEST_CASE("Stopping the status stream sends the printer a close frame", "[Moonra
     REQUIRE(f.printer.wait_for_ready_connections(1));
 
     CHECK(f.stops_within(3s));
+    CHECK(f.printer.wait_for_close_frames(1));
     CHECK(f.printer.close_frames() == 1);
 }