Re-enable running FS watcher test on OS X

Use a workaround to compensate for the differences between a non-GUI and
GUI event loop with wxOSX. This allows the FS watcher tests to pass
(previously it would hang) under OS X without having to move the tests
to the test GUI application (where the tests do pass on OS X already,
without needing this workaround).

See #16969.

tests/fswatcher/fswatchertest.cpp

@@ -30,6 +30,15 @@
 
 #include "testfile.h"
 
+/*
+This test used to be disabled on OS X as it hung. Work around the apparent
+wxOSX differences between a non-GUI event loop and a GUI event loop (where
+the tests do run fine) until this gets resolved.
+*/
+#ifdef __WXOSX__
+    #define OSX_EVENT_LOOP_WORKAROUND
+#endif
+
 // ----------------------------------------------------------------------------
 // local functions
 // ----------------------------------------------------------------------------
@@ -191,10 +200,16 @@ public:
     enum { WAIT_DURATION = 3 };
 
     EventHandler(int types = wxFSW_EVENT_ALL) :
-        eg(EventGenerator::Get()), m_loop(0), m_count(0), m_watcher(0),
+        eg(EventGenerator::Get()), m_loop(0),
-        m_eventTypes(types)
+#ifdef OSX_EVENT_LOOP_WORKAROUND
+        m_loopActivator(NULL),
+#endif
+        m_count(0), m_watcher(0), m_eventTypes(types)
     {
         m_loop = new wxEventLoop();
+#ifdef OSX_EVENT_LOOP_WORKAROUND
+        m_loopActivator = new wxEventLoopActivator(m_loop);
+#endif
         Connect(wxEVT_IDLE, wxIdleEventHandler(EventHandler::OnIdle));
         Connect(wxEVT_FSWATCHER, wxFileSystemWatcherEventHandler(
                                             EventHandler::OnFileSystemEvent));
@@ -203,6 +218,9 @@ public:
     virtual ~EventHandler()
     {
         delete m_watcher;
+#ifdef OSX_EVENT_LOOP_WORKAROUND
+        delete m_loopActivator;
+#endif
         if (m_loop)
         {
             if (m_loop->IsRunning())
@@ -221,6 +239,13 @@ public:
     {
         wxIdleEvent* e = new wxIdleEvent();
         QueueEvent(e);
+
+#ifdef OSX_EVENT_LOOP_WORKAROUND
+        // The fs watcher test cases will hang on OS X if Yield() is not called.
+        // It seems that the OS X event loop and / or queueing behaves
+        // differently than on MSW and Linux.
+        m_loop->Yield(true);
+#endif
     }
 
     void Run()
@@ -387,6 +412,9 @@ public:
 protected:
     EventGenerator& eg;
     wxEventLoopBase* m_loop;    // loop reference
+#ifdef OSX_EVENT_LOOP_WORKAROUND
+    wxEventLoopActivator* m_loopActivator;
+#endif
     int m_count;                // idle events count
 
     wxFileSystemWatcher* m_watcher;
@@ -459,15 +487,8 @@ private:
     wxDECLARE_NO_COPY_CLASS(FileSystemWatcherTestCase);
 };
 
-// the test currently hangs under OS X for some reason and this prevents tests
-// ran by buildbot from completing so disable it until someone has time to
-// debug it
-//
-// FIXME: debug and fix this!
-#ifndef __WXOSX__
 // register in the unnamed registry so that these tests are run by default
 CPPUNIT_TEST_SUITE_REGISTRATION( FileSystemWatcherTestCase );
-#endif
 
 // also include in its own registry so that these tests can be run alone
 CPPUNIT_TEST_SUITE_NAMED_REGISTRATION( FileSystemWatcherTestCase,
@@ -951,7 +972,16 @@ void FileSystemWatcherTestCase::TestTrees()
     };
 
     TreeTester tester;
+
+// The fs watcher test cases will hang on OS X if we call Run().
+// This is likely due to differences between the event loop
+// between OS X and the other ports.
+#ifdef OSX_EVENT_LOOP_WORKAROUND
+    tester.Init();
+    tester.GenerateEvent();
+#else
     tester.Run();
+#endif
 }