Advance Wayland and KDE package bring-up

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

local/recipes/kde/kf6-kpackage/source/autotests/fallbackpackagetest.cpp

@@ -0,0 +1,59 @@
+/*
+    SPDX-FileCopyrightText: 2007 Aaron Seigo <aseigo@kde.org>
+    SPDX-FileCopyrightText: 2014 Marco Martin <mart@kde.org>
+
+    SPDX-License-Identifier: LGPL-2.0-or-later
+*/
+
+#include "fallbackpackagetest.h"
+
+#include "packageloader.h"
+#include "packagestructure.h"
+#include <KLocalizedString>
+
+void FallbackPackageTest::initTestCase()
+{
+    m_fallPackagePath = QFINDTESTDATA("data/testpackage");
+    m_fallbackPkg = KPackage::PackageLoader::self()->loadPackage(QStringLiteral("KPackage/Generic"));
+    m_fallbackPkg.addFileDefinition("mainscript", QStringLiteral("ui/main.qml"));
+    m_fallbackPkg.setPath(m_fallPackagePath);
+
+    m_packagePath = QFINDTESTDATA("data/testfallbackpackage");
+    m_pkg = KPackage::PackageLoader::self()->loadPackage(QStringLiteral("KPackage/Generic"));
+    m_pkg.addFileDefinition("mainscript", QStringLiteral("ui/main.qml"));
+    m_pkg.setPath(m_packagePath);
+}
+
+void FallbackPackageTest::beforeFallback()
+{
+    QVERIFY(m_fallbackPkg.hasValidStructure());
+    QVERIFY(m_pkg.hasValidStructure());
+
+    // m_fallbackPkg should have otherfile.qml, m_pkg shouldn't
+    QVERIFY(!m_fallbackPkg.filePath("ui", QStringLiteral("otherfile.qml")).isEmpty());
+    QVERIFY(m_pkg.filePath("ui", QStringLiteral("otherfile.qml")).isEmpty());
+}
+
+void FallbackPackageTest::afterFallback()
+{
+    m_pkg.setFallbackPackage(m_fallbackPkg);
+
+    // after setting the fallback, m_pkg should resolve the exact same file as m_fallbackPkg
+    // for otherfile.qml
+    QVERIFY(!m_pkg.filePath("ui", QStringLiteral("otherfile.qml")).isEmpty());
+    QCOMPARE(m_fallbackPkg.filePath("ui", QStringLiteral("otherfile.qml")), m_pkg.filePath("ui", QStringLiteral("otherfile.qml")));
+    QVERIFY(m_fallbackPkg.filePath("mainscript") != m_pkg.filePath("mainscript"));
+}
+
+void FallbackPackageTest::cycle()
+{
+    m_fallbackPkg.setFallbackPackage(m_pkg);
+    m_pkg.setFallbackPackage(m_fallbackPkg);
+
+    // The cycle should have been detected and filePath should take a not infinite time
+    QTRY_COMPARE_WITH_TIMEOUT(m_fallbackPkg.filePath("ui", QStringLiteral("otherfile.qml")), m_pkg.filePath("ui", QStringLiteral("otherfile.qml")), 1000);
+}
+
+QTEST_MAIN(FallbackPackageTest)
+
+#include "moc_fallbackpackagetest.cpp"