Test that we can override an uncreatable singleton type with an instance

This is the most prominent use case for singleton instances. You
register a type for which you cannot manage the life cycle, but you have
one instance of it. That instance can now be registered at runtime to
override the static type registration.

Change-Id: I647b8df13f11f3385ead10ed7d3d617e536b8f87
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 14 insertions, 5 deletions

diff --git a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
index 7b4662a5cd..089daf3ed5 100644
--- a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
+++ b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
@@ -5378,25 +5378,34 @@ void tst_qqmllanguage::listContainingDeletedObject()
 
 void tst_qqmllanguage::overrideSingleton()
 {
-    auto check = [](const QString &name) {
+    auto check = [](const QString &name, const QByteArray &singletonElement) {
         const QByteArray testQml = "import Test 1.0\n"
                                    "import QtQml 2.0\n"
-                                   "QtObject { objectName: BareSingleton.objectName }";
+                                   "QtObject { objectName: " + singletonElement + ".objectName }";
         QQmlEngine engine;
         QQmlComponent component(&engine, nullptr);
-        component.setData(testQml, QUrl());
+        component.setData(testQml, QUrl("singleton.qml"));
         QVERIFY(component.isReady());
         QScopedPointer<QObject> obj(component.create());
         QCOMPARE(obj->objectName(), name);
     };
 
-    check("statically registered");
+    check("statically registered", "BareSingleton");
 
     BareSingleton singleton;
     singleton.setObjectName("dynamically registered");
     qmlRegisterSingletonInstance("Test", 1, 0, "BareSingleton", &singleton);
 
-    check("dynamically registered");
+    check("dynamically registered", "BareSingleton");
+
+    QTest::ignoreMessage(
+                QtWarningMsg,
+                "singleton.qml:3: TypeError: Cannot read property 'objectName' of undefined");
+    check("", "UncreatableSingleton");
+
+    qmlRegisterSingletonInstance("Test", 1, 0, "UncreatableSingleton",
+                                 UncreatableSingleton::instance());
+    check("uncreatable", "UncreatableSingleton");
 }
 
 QTEST_MAIN(tst_qqmllanguage)