Fix QPropertyAlias to work with all kinds of properties

So far QPropertyAlias was limited to working with QProperty<T>.
Change the implementation, so it can be constructed from any
property or even a QBindable<T>.

Change-Id: I175cffe94a9ef332367d39faa976eb065b0e6ffe
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 37 insertions, 0 deletions

diff --git a/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp b/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
index f5652eb599..9bc2ce26b6 100644
--- a/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
+++ b/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
@@ -78,6 +78,7 @@ private slots:
     void qobjectObservers();
     void compatBindings();
     void metaProperty();
+    void aliasOnMetaProperty();
 };
 
 void tst_QProperty::functorBinding()
@@ -1210,6 +1211,42 @@ void tst_QProperty::metaProperty()
     QCOMPARE(object.fooData.value(), 1);
 }
 
+void tst_QProperty::aliasOnMetaProperty()
+{
+    MyQObject object;
+    QPropertyAlias<int> alias(object.bindableFoo());
+
+    QVERIFY(alias.isValid());
+    QCOMPARE(alias.value(), object.foo());
+    QVERIFY(!alias.hasBinding());
+
+    object.setFoo(42);
+    QCOMPARE(alias.value(), 42);
+
+    auto f = [&object]() -> int {
+        return object.barData;
+    };
+    object.bindableFoo().setBinding(f);
+    QVERIFY(alias.hasBinding());
+    QCOMPARE(alias.value(), object.bar());
+
+    object.setBar(111);
+    QCOMPARE(alias.value(), 111);
+
+    int changedCount = 0;
+    auto observer = alias.onValueChanged([&changedCount]() { ++changedCount; });
+    QCOMPARE(changedCount, 0);
+    object.setBar(666);
+    QCOMPARE(changedCount, 1);
+
+    alias.setBinding([&object]() { return object.read(); });
+    QCOMPARE(changedCount, 2);
+    QCOMPARE(alias.value(), 0);
+    object.readData = 100;
+    QCOMPARE(changedCount, 3);
+    QCOMPARE(alias.value(), 100);
+}
+
 QTEST_MAIN(tst_QProperty);
 
 #include "tst_qproperty.moc"