Make QTestEventLoop::exitLoop() thread-safe

QTestEventLoop::exitLoop() is used by QSignalSpy to stop event
processing when the connected signal has been received. The design
of QSignalSpy requires QTestEventLoop::exitLoop() to be
thread-safe, which it wasn't. When QSignalSpy is connected
to a signal in a different thread, exitLoop() was called from
the thread which emitted the signal and not the one in which
QTestEventLoop is running. This caused troubles when killing
the internal timer.

This patch adds a check in the beginning of exitLoop(). If
it is called from a different thread, it will post an event
into the message queue in which QTestEventLoop is running
and execute it there.

Change-Id: Icb8c8ff2f5344800ee6c6125b98c677c7a196c32
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/testlib/qtesteventloop.h

@@ -40,6 +40,7 @@
 #include <QtCore/qeventloop.h>
 #include <QtCore/qobject.h>
 #include <QtCore/qpointer.h>
+#include <QtCore/qthread.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -101,6 +102,12 @@ inline void QTestEventLoop::enterLoopMSecs(int ms)
 
 inline void QTestEventLoop::exitLoop()
 {
+    if (thread() != QThread::currentThread())
+    {
+        QMetaObject::invokeMethod(this, "exitLoop", Qt::QueuedConnection);
+        return;
+    }
+
     if (timerId != -1)
         killTimer(timerId);
     timerId = -1;