This is a general collection of knowledge for ParaView developers.
Because of the testing framework we are unable to safely use processEvents. The testing framework has a busy lock it uses to determine when it should play the next testing event. If that busy lock is running when your code calls processEvents it will cause the tests to start playing, which will break the test. The solution is dependent on where you need to call processEvents.
pqCoreUtilities::processEvents(); pqEventDispatcher::processEvents(); //only in Widgets since widgets can't depend on core
Both methods support the QEventLoop::ProcessEventsFlags flags argument. For more information on processEvents please see the Qt Documentation