Stabilize tst_QStateMachine::dontProcessSlotsWhenMachineIsNotRunning

The test is flaky which was uncovered by the upcoming
QTimer::singleShot optimization patches:

When the Emitter's thread is started and executes the timout functor
before the state machine is started, then the state machine will never
see the emitSignalWithNoArg signal and thus never transition to the
final state and finish.

This patch ensures that the code in the background thread is only run
after the state machine was started to fix this flakyness.

Change-Id: I6f91a2420165662ece75e550a6d73fe098137d4c
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Reviewed-by: Kari Oikarinen <kari.oikarinen@qt.io>

1 files changed, 4 insertions, 4 deletions

diff --git a/tests/auto/corelib/statemachine/qstatemachine/tst_qstatemachine.cpp b/tests/auto/corelib/statemachine/qstatemachine/tst_qstatemachine.cpp
index 810698fb4e..55a672aae1 100644
--- a/tests/auto/corelib/statemachine/qstatemachine/tst_qstatemachine.cpp
+++ b/tests/auto/corelib/statemachine/qstatemachine/tst_qstatemachine.cpp
@@ -6680,13 +6680,13 @@ void tst_QStateMachine::dontProcessSlotsWhenMachineIsNotRunning()
     } emitter;
 
     initialState.addTransition(&emitter, &Emitter::signalWithNoArg, &finalState);
-    QTimer::singleShot(0, [&]() {
-        metaObject()->invokeMethod(&emitter, "emitSignalWithNoArg");
-        metaObject()->invokeMethod(&emitter, "emitSignalWithNoArg");
-    });
     machine.addState(&initialState);
     machine.addState(&finalState);
     machine.setInitialState(&initialState);
+    connect(&machine, &QStateMachine::started, &emitter, [&]() {
+        metaObject()->invokeMethod(&emitter, "emitSignalWithNoArg");
+        metaObject()->invokeMethod(&emitter, "emitSignalWithNoArg");
+    });
     connect(&machine, &QStateMachine::finished, &emitter.thread, &QThread::quit);
     machine.start();
     QSignalSpy emittedSpy(&emitter, &SignalEmitter::signalWithNoArg);