Add a test for a crash in ModelManagerInterface

Task-number: QTCREATORBUG-25350
Change-Id: I4ea31e7936cc77dcd8f3fc494b5ecbd83858a766
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/libs/extensionsystem/pluginmanager.cpp

@@ -1393,6 +1393,12 @@ void PluginManagerPrivate::shutdown()
         shutdownEventLoop->exec();
     }
     deleteAll();
+#ifdef WITH_TESTS
+    if (PluginManager::isScenarioRunning("TestModelManagerInterface")) {
+        qDebug() << "Point 2: Expect the next call to Point 3 triggers a crash";
+        QThread::currentThread()->sleep(5);
+    }
+#endif
     if (!allObjects.isEmpty()) {
         qDebug() << "There are" << allObjects.size() << "objects left in the plugin manager pool.";
         // Intentionally split debug info here, since in case the list contains