Android: add an appless test that recreates QGuiApplication

Make sure this works and doesn't cause any QJniEnvironment or other
JNI object lifetime issues.

Change-Id: I08b55982266dfb1821517449f6eb9f2796cea9b7
Reviewed-by: Juha Vuolle <juha.vuolle@qt.io>

tests/auto/corelib/platform/CMakeLists.txt

@@ -3,6 +3,7 @@
 
 if(ANDROID)
     add_subdirectory(android)
+    add_subdirectory(android_appless)
 endif()
 if(WIN32)
     add_subdirectory(windows)

tests/auto/corelib/platform/android_appless/CMakeLists.txt

@@ -0,0 +1,19 @@
+# Copyright (C) 2023 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+#####################################################################
+## tst_android_appless Test:
+#####################################################################
+
+if(NOT QT_BUILD_STANDALONE_TESTS AND NOT QT_BUILDING_QT)
+    cmake_minimum_required(VERSION 3.16)
+    project(tst_android_appless LANGUAGES CXX)
+    find_package(Qt6BuildInternals REQUIRED COMPONENTS STANDALONE_TEST)
+endif()
+
+qt_internal_add_test(tst_android_appless
+    SOURCES
+    tst_android_appless.cpp
+    LIBRARIES
+        Qt::Gui
+)

tests/auto/corelib/platform/android_appless/tst_android_appless.cpp

@@ -0,0 +1,53 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#include <QTest>
+#include <QTimer>
+#include <QGuiApplication>
+#include <QWindow>
+
+using namespace Qt::StringLiterals;
+
+class tst_AndroidAppless : public QObject
+{
+    Q_OBJECT
+private slots:
+    void app_data();
+    void app();
+
+};
+
+#define CREATE_DUMMY_ARGC_ARGV() \
+    int argc = 1; \
+    char *argv[] = { const_cast<char *>("tst_android_appless") };
+
+
+void tst_AndroidAppless::app_data()
+{
+    QTest::addColumn<QString>("displayName");
+    QTest::addRow("one") << "The first QGuiApplication instance";
+    QTest::addRow("two") << "The second QGuiApplication instance";
+}
+
+void tst_AndroidAppless::app()
+{
+    QFETCH(const QString, displayName);
+    CREATE_DUMMY_ARGC_ARGV()
+
+    QGuiApplication app(argc, argv);
+    app.setApplicationDisplayName(displayName);
+
+    QWindow window;
+    window.show();
+
+    QTimer::singleShot(1000, &app, QGuiApplication::quit);
+
+    window.show();
+    app.exec();
+}
+
+#undef CREATE_DUMMY_ARGC_ARGV
+
+QTEST_APPLESS_MAIN(tst_AndroidAppless)
+#include "tst_android_appless.moc"
+