Qt event loop and unit testing?

Question

I\'we started experimenting with unit testing in Qt and would like to hear comments on a scenario that involves unit testing signals and slots.

Here is an example:

Answer 1

I had a similar issue with Qt::QueuedConnection (event is queued automatically if the sender and the receiver belongs to different threads). Without a proper event loop in that situation, the internal state of objects depending on event processing will not be updated. To start an event loop when running QTest, change the macro QTEST_APPLESS_MAIN at the bottom of the file to QTEST_MAIN. Then, calling qApp->processEvents() will actually process events, or you can start another event loop with QEventLoop.

   QSignalSpy spy(&foo, SIGNAL(ready()));
   connect(&foo, SIGNAL(ready()), &bar, SLOT(work()), Qt::QueuedConnection);
   foo.emitReady();
   QCOMPARE(spy.count(), 1);        // QSignalSpy uses Qt::DirectConnection
   QCOMPARE(bar.received, false);   // bar did not receive the signal, but that is normal: there is no active event loop
   qApp->processEvents();           // Manually trigger event processing ...
   QCOMPARE(bar.received, true);    // bar receives the signal only if QTEST_MAIN() is used