Prepare tests for upcoming incremental gc

This commit:
- Introduces helper functions gcDone and gc. gcDone simply returns true
  as the gc is currently not incremental. gc is a helper method which
  has been copied into various tests already, which runs the garbage
  collections and sends events to clean up objects scheduled for
  deletion. The new helpers are placed in qmlutils.cpp.
- It adds a flag to gc which allows not sending the posted events. That
  allows using gc in more places, while highlighting the fact that we
  don't want to process events at this point. This will also help
  upcoming changes to the incremental gc, which by default will use the
  event loop to drive the gc processing
- It moves some gc calls from QML to C++ – this again will help later to
  ensure that the gc actually has completed

As a driveby, the logging rules early in tst_qv4mm are reset earlier.

Task-number: QTBUG-119274
Change-Id: I75d6ffcb3aa459b020e8257155faa91c39653d43
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

16 files changed, 46 insertions, 79 deletions

diff --git a/tests/auto/qml/qjsengine/CMakeLists.txt b/tests/auto/qml/qjsengine/CMakeLists.txt
index e013e67033..452eafa3ad 100644
--- a/tests/auto/qml/qjsengine/CMakeLists.txt
+++ b/tests/auto/qml/qjsengine/CMakeLists.txt
@@ -34,6 +34,7 @@ qt_internal_add_test(tst_qjsengine
         Qt::GuiPrivate
         Qt::Qml
         Qt::QmlPrivate
+        Qt::QuickTestUtilsPrivate
     LIBRARIES # special case
         Threads::Threads # special case
     TESTDATA ${test_data} "dummy_imports.qml"
diff --git a/tests/auto/qml/qjsengine/tst_qjsengine.cpp b/tests/auto/qml/qjsengine/tst_qjsengine.cpp
index 8caa1f215b..5287f81538 100644
--- a/tests/auto/qml/qjsengine/tst_qjsengine.cpp
+++ b/tests/auto/qml/qjsengine/tst_qjsengine.cpp
@@ -18,6 +18,7 @@
 #include <QUrl>
 #include <QModelIndex>
 #include <QtQml/qqmllist.h>
+#include <QtQuickTestUtils/private/qmlutils_p.h>
 
 #ifdef Q_CC_MSVC
 #define NO_INLINE __declspec(noinline)
@@ -941,7 +942,7 @@ void tst_QJSEngine::newQObject_ownership()
         {
             QJSValue v = eng.newQObject(ptr);
         }
-        eng.collectGarbage();
+        gc(*eng.handle(), GCFlags::DontSendPostedEvents);
         if (ptr)
             QGuiApplication::sendPostedEvents(ptr, QEvent::DeferredDelete);
         QVERIFY(ptr.isNull());
@@ -1926,7 +1927,7 @@ void tst_QJSEngine::collectGarbage()
     QPointer<QObject> ptr = new QObject();
     QVERIFY(ptr != nullptr);
     (void)eng.newQObject(ptr);
-    eng.collectGarbage();
+    gc(*eng.handle(), GCFlags::DontSendPostedEvents);
     if (ptr)
         QGuiApplication::sendPostedEvents(ptr, QEvent::DeferredDelete);
     QVERIFY(ptr.isNull());
@@ -1961,8 +1962,8 @@ void tst_QJSEngine::collectGarbageNestedWrappersTwoEngines()
     QCOMPARE(engine1.evaluate("foobar.dummy.baz").toInt(), 42);
     QCOMPARE(engine2.evaluate("foobar.dummy.baz").toInt(), 43);
 
-    engine1.collectGarbage();
-    engine2.collectGarbage();
+    gc(*engine1.handle());
+    gc(*engine2.handle());
 
     // The GC should not collect dummy object wrappers neither in engine1 nor engine2, we
     // verify that by checking whether the baz property still has its previous value.
@@ -3900,7 +3901,7 @@ void tst_QJSEngine::prototypeChainGc()
     QJSValue factory = engine.evaluate("(function() { return Object.create(Object.create({})); })");
     QVERIFY(factory.isCallable());
     QJSValue obj = factory.call();
-    engine.collectGarbage();
+    gc(*engine.handle());
 
     QJSValue proto = getProto.call(QJSValueList() << obj);
     proto = getProto.call(QJSValueList() << proto);
@@ -3919,7 +3920,7 @@ void tst_QJSEngine::prototypeChainGc_QTBUG38299()
                     "delete mapping.prop1\n"
                     "\n");
     // Don't hang!
-    engine.collectGarbage();
+    gc(*engine.handle());
 }
 
 void tst_QJSEngine::dynamicProperties()
diff --git a/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp b/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp
index 542569df03..acf03c51b7 100644
--- a/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp
+++ b/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp
@@ -90,13 +90,6 @@ public slots:
     }
 };
 
-static void gc(QQmlEngine &engine)
-{
-    engine.collectGarbage();
-    QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
-    QCoreApplication::processEvents();
-}
-
 class tst_qqmlcomponent : public QQmlDataTest
 {
     Q_OBJECT
diff --git a/tests/auto/qml/qqmlcontext/tst_qqmlcontext.cpp b/tests/auto/qml/qqmlcontext/tst_qqmlcontext.cpp
index 2e6626c08d..70728cf03f 100644
--- a/tests/auto/qml/qqmlcontext/tst_qqmlcontext.cpp
+++ b/tests/auto/qml/qqmlcontext/tst_qqmlcontext.cpp
@@ -824,7 +824,7 @@ void tst_qqmlcontext::contextLeak()
         scriptContext = scriptContextWrapper->as<QV4::QQmlContextWrapper>()->getContext();
     }
 
-    engine.collectGarbage();
+    gc(engine);
 
     // Each time a JS file (non-pragma-shared) is imported, we create a QQmlContext(Data) for it.
     // Make sure that context does not leak.
diff --git a/tests/auto/qml/qqmlecmascript/data/PropertyVarCircularComponent4.qml b/tests/auto/qml/qqmlecmascript/data/PropertyVarCircularComponent4.qml
index 9273a52f54..ff7fe4434c 100644
--- a/tests/auto/qml/qqmlecmascript/data/PropertyVarCircularComponent4.qml
+++ b/tests/auto/qml/qqmlecmascript/data/PropertyVarCircularComponent4.qml
@@ -22,7 +22,6 @@ Rectangle {
             if (component.status == Component.Ready) {
                 text.vp = component.createObject(null); // has JavaScript ownership
             }
-            gc();
         }
     }
 }
diff --git a/tests/auto/qml/qqmlecmascript/data/PropertyVarOwnershipComponent.qml b/tests/auto/qml/qqmlecmascript/data/PropertyVarOwnershipComponent.qml
index f4307081c5..4e8da872f5 100644
--- a/tests/auto/qml/qqmlecmascript/data/PropertyVarOwnershipComponent.qml
+++ b/tests/auto/qml/qqmlecmascript/data/PropertyVarOwnershipComponent.qml
@@ -25,7 +25,6 @@ Rectangle {
             if (component.status == Component.Ready) {
                 textTwo.vp = component.createObject(null); // has JavaScript ownership
             }
-            gc();
         }
 
         function deassignVp() {
diff --git a/tests/auto/qml/qqmlecmascript/data/propertyVar.reparent.qml b/tests/auto/qml/qqmlecmascript/data/propertyVar.reparent.qml
index 6f5094de27..5f017c4880 100644
--- a/tests/auto/qml/qqmlecmascript/data/propertyVar.reparent.qml
+++ b/tests/auto/qml/qqmlecmascript/data/propertyVar.reparent.qml
@@ -16,7 +16,6 @@ Item {
 
     function assignVarProp() {
         vp = constructGarbage();
-        gc();
     }
 
     function deassignVarProp() {
diff --git a/tests/auto/qml/qqmlecmascript/data/propertyVarImplicitOwnership.qml b/tests/auto/qml/qqmlecmascript/data/propertyVarImplicitOwnership.qml
index ecc4892334..144fcc8a93 100644
--- a/tests/auto/qml/qqmlecmascript/data/propertyVarImplicitOwnership.qml
+++ b/tests/auto/qml/qqmlecmascript/data/propertyVarImplicitOwnership.qml
@@ -16,7 +16,6 @@ Item {
 
     function assignCircular() {
         vp = constructGarbage();
-        gc();
     }
 
     function deassignCircular() {
diff --git a/tests/auto/qml/qqmlecmascript/testtypes.cpp b/tests/auto/qml/qqmlecmascript/testtypes.cpp
index 681db089d6..71c7eca1f5 100644
--- a/tests/auto/qml/qqmlecmascript/testtypes.cpp
+++ b/tests/auto/qml/qqmlecmascript/testtypes.cpp
@@ -9,6 +9,7 @@
 #include <QQmlEngine>
 #include <QJSEngine>
 #include <QThread>
+#include <QtQuickTestUtils/private/qmlutils_p.h>
 
 class BaseExtensionObject : public QObject
 {
@@ -394,9 +395,7 @@ void QObjectContainer::children_append(QQmlListProperty<QObject> *prop, QObject
 
     if (that->gcOnAppend) {
         QQmlEngine *engine = qmlEngine(that);
-        engine->collectGarbage();
-        QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
-        QCoreApplication::processEvents();
+        gc(*engine);
     }
 }
 
diff --git a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
index 787bac1520..35b7e6a535 100644
--- a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
+++ b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
@@ -444,14 +444,6 @@ private:
     }
 };
 
-static void gc(QQmlEngine &engine)
-{
-    engine.collectGarbage();
-    QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
-    QCoreApplication::processEvents();
-}
-
-
 tst_qqmlecmascript::tst_qqmlecmascript()
     : QQmlDataTest(QT_QMLTEST_DATADIR)
 {
@@ -4082,10 +4074,7 @@ void tst_qqmlecmascript::ownership()
 
         QScopedPointer<QObject> object(component.create(context.data()));
 
-        engine.collectGarbage();
-
-        QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
-        QCoreApplication::processEvents();
+        gc(engine);
 
         QVERIFY(own.object.isNull());
     }
@@ -4099,10 +4088,7 @@ void tst_qqmlecmascript::ownership()
 
         QScopedPointer<QObject> object(component.create(context.data()));
 
-        engine.collectGarbage();
-
-        QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
-        QCoreApplication::processEvents();
+        gc(engine);
 
         QVERIFY(own.object != nullptr);
     }
@@ -4178,9 +4164,7 @@ void tst_qqmlecmascript::ownershipCustomReturnValue()
     QVERIFY(source.value != nullptr);
     }
 
-    engine.collectGarbage();
-    QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
-    QCoreApplication::processEvents();
+    gc(engine);
 
     QVERIFY(source.value.isNull());
 }
@@ -4211,10 +4195,7 @@ void tst_qqmlecmascript::ownershipRootObject()
     QScopedPointer<QObject> object(component.create(context.data()));
     QVERIFY2(object, qPrintable(component.errorString()));
 
-    engine.collectGarbage();
-
-    QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
-    QCoreApplication::processEvents();
+    gc(engine);
 
     QVERIFY(own.object != nullptr);
 }
@@ -4239,10 +4220,7 @@ void tst_qqmlecmascript::ownershipConsistency()
     QScopedPointer<QObject> object(component.create(context.data()));
     QVERIFY2(object, qPrintable(component.errorString()));
 
-    engine.collectGarbage();
-
-    QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
-    QCoreApplication::processEvents();
+    gc(engine);
 
     QVERIFY(own.object != nullptr);
 }
@@ -4772,6 +4750,7 @@ void tst_qqmlecmascript::verifyContextLifetime(const QQmlRefPointer<QQmlContextD
             }
 
             ctxt->engine()->collectGarbage();
+            QTRY_VERIFY(gcDone(ctxt->engine()));
             qml = scripts->get(i);
             newContext = qml ? qml->getContext() : nullptr;
             QCOMPARE(scriptContext.data(), newContext.data());
@@ -5599,7 +5578,9 @@ void tst_qqmlecmascript::propertyVarOwnership()
     QScopedPointer<QObject> object(component.create());
     QVERIFY2(object, qPrintable(component.errorString()));
     QMetaObject::invokeMethod(object.data(), "createComponent");
-    engine.collectGarbage();
+    // This test only works if we don't deliver the pending delete later event
+    // that collectGarbage will post before calling runTest
+    gc(engine, GCFlags::DontSendPostedEvents);
     QMetaObject::invokeMethod(object.data(), "runTest");
     QCOMPARE(object->property("test").toBool(), true);
     }
@@ -5615,8 +5596,7 @@ void tst_qqmlecmascript::propertyVarImplicitOwnership()
     QScopedPointer<QObject> object(component.create());
     QVERIFY2(object, qPrintable(component.errorString()));
     QMetaObject::invokeMethod(object.data(), "assignCircular");
-    QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete); // process deleteLater() events from QV8QObjectWrapper.
-    QCoreApplication::processEvents();
+    gc(engine);
     QObject *rootObject = object->property("vp").value<QObject*>();
     QVERIFY(rootObject != nullptr);
     QObject *childObject = rootObject->findChild<QObject*>("text");
@@ -5625,6 +5605,8 @@ void tst_qqmlecmascript::propertyVarImplicitOwnership()
     QCOMPARE(childObject->property("textCanary").toInt(), 10);
     // Creates a reference to a constructed QObject:
     QMetaObject::invokeMethod(childObject, "constructQObject");
+    // Don't send delete later events yet, we do it manually later
+    gc(engine, GCFlags::DontSendPostedEvents);
     QPointer<QObject> qobjectGuard(childObject->property("vp").value<QObject*>()); // get the pointer prior to processing deleteLater events.
     QVERIFY(!qobjectGuard.isNull());
     QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete); // process deleteLater() events from QV8QObjectWrapper.
@@ -5643,8 +5625,7 @@ void tst_qqmlecmascript::propertyVarReparent()
     QScopedPointer<QObject> object(component.create());
     QVERIFY2(object, qPrintable(component.errorString()));
     QMetaObject::invokeMethod(object.data(), "assignVarProp");
-    QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete); // process deleteLater() events from QV8QObjectWrapper.
-    QCoreApplication::processEvents();
+    gc(engine);
     QObject *rect = object->property("vp").value<QObject*>();
     QObject *text = rect->findChild<QObject*>("textOne");
     QObject *text2 = rect->findChild<QObject*>("textTwo");
@@ -5658,6 +5639,7 @@ void tst_qqmlecmascript::propertyVarReparent()
     QCOMPARE(text2->property("textCanary").toInt(), 12);
     // now construct an image which we will reparent.
     QMetaObject::invokeMethod(text2, "constructQObject");
+    gc(engine, GCFlags::DontSendPostedEvents);
     QObject *image = text2->property("vp").value<QObject*>();
     QPointer<QObject> imageGuard(image);
     QVERIFY(!imageGuard.isNull());
@@ -5685,8 +5667,7 @@ void tst_qqmlecmascript::propertyVarReparentNullContext()
     QScopedPointer<QObject> object(component.create());
     QVERIFY2(object, qPrintable(component.errorString()));
     QMetaObject::invokeMethod(object.data(), "assignVarProp");
-    QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete); // process deleteLater() events from QV8QObjectWrapper.
-    QCoreApplication::processEvents();
+    gc(engine);
     QObject *rect = object->property("vp").value<QObject*>();
     QObject *text = rect->findChild<QObject*>("textOne");
     QObject *text2 = rect->findChild<QObject*>("textTwo");
@@ -5700,6 +5681,7 @@ void tst_qqmlecmascript::propertyVarReparentNullContext()
     QCOMPARE(text2->property("textCanary").toInt(), 12);
     // now construct an image which we will reparent.
     QMetaObject::invokeMethod(text2, "constructQObject");
+    gc(engine);
     QObject *image = text2->property("vp").value<QObject*>();
     QPointer<QObject> imageGuard(image);
     QVERIFY(!imageGuard.isNull());
@@ -5926,9 +5908,7 @@ void tst_qqmlecmascript::handleReferenceManagement()
         gc(hrmEngine);
         QCOMPARE(dtorCount, 0); // second has JS ownership, kept alive by first's reference
         object.reset();
-        hrmEngine.collectGarbage();
-        QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
-        QCoreApplication::processEvents();
+        gc(hrmEngine);
         QCOMPARE(dtorCount, 3);
     }
 
@@ -5945,9 +5925,7 @@ void tst_qqmlecmascript::handleReferenceManagement()
         gc(hrmEngine);
         QCOMPARE(dtorCount, 2); // both should be cleaned up, since circular references shouldn't keep alive.
         object.reset();
-        hrmEngine.collectGarbage();
-        QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
-        QCoreApplication::processEvents();
+        gc(hrmEngine);
         QCOMPARE(dtorCount, 3);
     }
 
@@ -8224,7 +8202,9 @@ void tst_qqmlecmascript::qqmldataDestroyed()
         QVERIFY2(object, qPrintable(c.errorString()));
         // now gc causing the collection of the dynamically constructed object.
         engine.collectGarbage();
+        QTRY_VERIFY(gcDone(&engine));
         engine.collectGarbage();
+        QTRY_VERIFY(gcDone(&engine));
         // now process events to allow deletion (calling qqmldata::destroyed())
         QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
         QCoreApplication::processEvents();
diff --git a/tests/auto/qml/qqmlengine/tst_qqmlengine.cpp b/tests/auto/qml/qqmlengine/tst_qqmlengine.cpp
index b0fb3b17e1..6ed45a1c52 100644
--- a/tests/auto/qml/qqmlengine/tst_qqmlengine.cpp
+++ b/tests/auto/qml/qqmlengine/tst_qqmlengine.cpp
@@ -435,7 +435,7 @@ public:
         // There might be JS function objects around that hold a last ref to the compilation unit that's
         // keeping the type compilation data (CompilationUnit) around. Let's collect them as well so that
         // trim works well.
-        engine->collectGarbage();
+        gc(*engine);
 
         engine->trimComponentCache();
     }
diff --git a/tests/auto/qml/qqmlincubator/tst_qqmlincubator.cpp b/tests/auto/qml/qqmlincubator/tst_qqmlincubator.cpp
index 1baf61574e..ced13df841 100644
--- a/tests/auto/qml/qqmlincubator/tst_qqmlincubator.cpp
+++ b/tests/auto/qml/qqmlincubator/tst_qqmlincubator.cpp
@@ -1148,7 +1148,7 @@ void tst_qqmlincubator::garbageCollection()
     QQmlComponent component(&engine, testFileUrl("garbageCollection.qml"));
     QScopedPointer<QObject> obj(component.create());
 
-    engine.collectGarbage();
+    gc(engine);
 
     std::atomic<bool> b{true};
     controller.incubateWhile(&b);
@@ -1166,7 +1166,7 @@ void tst_qqmlincubator::garbageCollection()
     incubatorVariant.clear();
 
     // verify incubator is correctly collected now that incubation is complete and all references are gone
-    engine.collectGarbage();
+    gc(engine);
     QVERIFY(weakIncubatorRef.isNullOrUndefined());
 }
 
diff --git a/tests/auto/qml/qqmlqt/tst_qqmlqt.cpp b/tests/auto/qml/qqmlqt/tst_qqmlqt.cpp
index b9ef18d314..f66e0c5ffc 100644
--- a/tests/auto/qml/qqmlqt/tst_qqmlqt.cpp
+++ b/tests/auto/qml/qqmlqt/tst_qqmlqt.cpp
@@ -1300,7 +1300,7 @@ void tst_qqmlqt::later()
             QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
             QCoreApplication::processEvents();
         } else if (propNames.at(i) == QLatin1String("collectGarbage")) {
-            engine.collectGarbage();
+            gc(engine, GCFlags::DontSendPostedEvents);
         } else {
             QCOMPARE(root->property(qPrintable(propNames.at(i))), values.at(i));
         }
diff --git a/tests/auto/qml/qv4mm/tst_qv4mm.cpp b/tests/auto/qml/qv4mm/tst_qv4mm.cpp
index e5f8951825..a36c8a8358 100644
--- a/tests/auto/qml/qv4mm/tst_qv4mm.cpp
+++ b/tests/auto/qml/qv4mm/tst_qv4mm.cpp
@@ -38,7 +38,8 @@ void tst_qv4mm::gcStats()
 {
     QLoggingCategory::setFilterRules("qt.qml.gc.*=true");
     QQmlEngine engine;
-    engine.collectGarbage();
+    gc(engine);
+    QLoggingCategory::setFilterRules("qt.qml.gc.*=false");
 }
 
 void tst_qv4mm::multiWrappedQObjects()
@@ -62,27 +63,27 @@ void tst_qv4mm::multiWrappedQObjects()
 
         // The additional WeakValue from m_multiplyWrappedQObjects hasn't been moved
         // to m_pendingFreedObjectWrapperValue yet. It's still alive after all.
-        engine1.memoryManager->runGC();
+        gc(engine1);
         QCOMPARE(engine1.memoryManager->m_pendingFreedObjectWrapperValue.size(), 1);
 
         // engine2 doesn't own the object as engine1 was the first to wrap it above.
         // Therefore, no effect here.
-        engine2.memoryManager->runGC();
+        gc(engine2);
         QCOMPARE(engine2.memoryManager->m_pendingFreedObjectWrapperValue.size(), 0);
     }
 
     // Clears m_pendingFreedObjectWrapperValue. Now it's really dead.
-    engine1.memoryManager->runGC();
+    gc(engine1);
     QCOMPARE(engine1.memoryManager->m_pendingFreedObjectWrapperValue.size(), 0);
 
-    engine2.memoryManager->runGC();
+    gc(engine2);
     QCOMPARE(engine2.memoryManager->m_pendingFreedObjectWrapperValue.size(), 0);
 }
 
 void tst_qv4mm::accessParentOnDestruction()
 {
-    QLoggingCategory::setFilterRules("qt.qml.gc.*=false");
     QQmlEngine engine;
+
     QQmlComponent component(&engine, testFileUrl("createdestroy.qml"));
     std::unique_ptr<QObject> obj(component.create());
     QVERIFY(obj);
@@ -91,6 +92,7 @@ void tst_qv4mm::accessParentOnDestruction()
     QTRY_VERIFY(!timer->property("running").toBool());
     QCOMPARE(obj->property("iterations").toInt(), 100);
     QCOMPARE(obj->property("creations").toInt(), 100);
+    gc(engine); // ensure incremental gc has finished, and collected all objects
     QCOMPARE(obj->property("destructions").toInt(), 100);
 }
 
@@ -181,7 +183,7 @@ void tst_qv4mm::cleanInternalClasses()
     }
 
     // Make sure that all dangling ICs are actually gone.
-    scope.engine->memoryManager->runGC();
+    gc(engine);
 
     // Now the GC has removed the ICs we originally added by adding properties.
     QVERIFY(prevIC->d()->transitions.empty() || prevIC->d()->transitions.front().lookup == nullptr);
diff --git a/tests/auto/qml/qwidgetsinqml/CMakeLists.txt b/tests/auto/qml/qwidgetsinqml/CMakeLists.txt
index 72164698b3..d2374997f2 100644
--- a/tests/auto/qml/qwidgetsinqml/CMakeLists.txt
+++ b/tests/auto/qml/qwidgetsinqml/CMakeLists.txt
@@ -21,6 +21,7 @@ qt_internal_add_test(tst_qwidgetsinqml
         Qt::GuiPrivate
         Qt::Qml
         Qt::Widgets
+        Qt::QuickTestUtilsPrivate
     TESTDATA "dummy_imports.qml"
 )
 
diff --git a/tests/auto/qml/qwidgetsinqml/tst_qwidgetsinqml.cpp b/tests/auto/qml/qwidgetsinqml/tst_qwidgetsinqml.cpp
index 32d5c0d832..46e925aee4 100644
--- a/tests/auto/qml/qwidgetsinqml/tst_qwidgetsinqml.cpp
+++ b/tests/auto/qml/qwidgetsinqml/tst_qwidgetsinqml.cpp
@@ -5,6 +5,7 @@
 #include <QQmlEngine>
 #include <QtQml>
 #include <QWidget>
+#include <QtQuickTestUtils/private/qmlutils_p.h>
 
 class tst_QWidgetsInQml : public QObject
 {
@@ -20,13 +21,6 @@ private slots:
     void widgetAsDefaultPropertyKeptDuringCreation();
 };
 
-static void gc(QQmlEngine &engine)
-{
-    engine.collectGarbage();
-    QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
-    QCoreApplication::processEvents();
-}
-
 // Like QtObject, but with default property
 class QObjectContainer : public QObject
 {