Restructure tests in preparation for merging into qtdeclarative

Task-number: QTBUG-95173
Change-Id: I541dc26cf2cdd6f2640824f693f7d059445367d9
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit f865f4b76d9385077c9ba4ca91a91246554dd36e)
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

17 files changed, 435 insertions, 0 deletions

diff --git a/tests/auto/quickcontrols2/styleimports/CMakeLists.txt b/tests/auto/quickcontrols2/styleimports/CMakeLists.txt
new file mode 100644
index 0000000000..9e612bc7a4
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/CMakeLists.txt
@@ -0,0 +1,66 @@
+# Generated from styleimports.pro.
+
+#####################################################################
+## tst_styleimports Test:
+#####################################################################
+
+# Collect test data
+file(GLOB_RECURSE test_data_glob
+    RELATIVE ${CMAKE_CURRENT_SOURCE_DIR}
+    data/*)
+list(APPEND test_data ${test_data_glob})
+
+qt_internal_add_test(tst_styleimports
+    SOURCES
+        ../shared/qtest_quickcontrols.h
+        ../shared/util.cpp ../shared/util.h
+        ../shared/visualtestutil.cpp ../shared/visualtestutil.h
+        tst_styleimports.cpp
+    DEFINES
+        QQC2_IMPORT_PATH=\\\"${CMAKE_CURRENT_SOURCE_DIR}/../../../../src\\\"
+    PUBLIC_LIBRARIES
+        Qt::CorePrivate
+        Qt::Gui
+        Qt::GuiPrivate
+        Qt::QmlPrivate
+        Qt::QuickControls2
+        Qt::QuickControls2ImplPrivate
+        Qt::QuickControls2Private
+        Qt::QuickPrivate
+        Qt::QuickTemplates2Private
+        Qt::QuickTest
+        Qt::TestPrivate
+    TESTDATA ${test_data}
+)
+
+# Resources:
+set(qmake_resourcestyle_resource_files
+    "resources/ResourceStyle/Button.qml"
+    "resources/ResourceStyle/qmldir"
+)
+
+qt_internal_add_resource(tst_styleimports "qmake_resourcestyle"
+    PREFIX
+        "/"
+    BASE
+        "resources"
+    FILES
+        ${qmake_resourcestyle_resource_files}
+)
+
+
+#### Keys ignored in scope 1:.:.:styleimports.pro:<TRUE>:
+# OTHER_FILES = "data/*.qml" "data/qmldir" "data/FileSystemStyle/*.qml" "data/FileSystemStyle/qmldir" "data/PlatformStyle/*.qml" "data/PlatformStyle/+linux/*.qml" "data/PlatformStyle/+macos/*.qml" "data/PlatformStyle/+windows/*.qml" "data/PlatformStyle/qmldir"
+
+## Scopes:
+#####################################################################
+
+qt_internal_extend_target(tst_styleimports CONDITION ANDROID OR IOS
+    DEFINES
+        QT_QMLTEST_DATADIR=\\\":/data\\\"
+)
+
+qt_internal_extend_target(tst_styleimports CONDITION NOT ANDROID AND NOT IOS
+    DEFINES
+        QT_QMLTEST_DATADIR=\\\"${CMAKE_CURRENT_SOURCE_DIR}/data\\\"
+)
diff --git a/tests/auto/quickcontrols2/styleimports/ResourceStyle/Button.qml b/tests/auto/quickcontrols2/styleimports/ResourceStyle/Button.qml
new file mode 100644
index 0000000000..656b27a739
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/ResourceStyle/Button.qml
@@ -0,0 +1,4 @@
+import QtQuick.Templates as T
+T.Button {
+    objectName: "ResourceStyle"
+}
diff --git a/tests/auto/quickcontrols2/styleimports/data/Action.qml b/tests/auto/quickcontrols2/styleimports/data/Action.qml
new file mode 100644
index 0000000000..f49c6ff42d
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/data/Action.qml
@@ -0,0 +1,4 @@
+import QtQuick.Templates as T
+T.Action {
+    objectName: "data"
+}
diff --git a/tests/auto/quickcontrols2/styleimports/data/Button.qml b/tests/auto/quickcontrols2/styleimports/data/Button.qml
new file mode 100644
index 0000000000..85367472b7
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/data/Button.qml
@@ -0,0 +1,4 @@
+import QtQuick.Templates as T
+T.Button {
+    objectName: "data"
+}
diff --git a/tests/auto/quickcontrols2/styleimports/data/FileSystemStyle/Button.qml b/tests/auto/quickcontrols2/styleimports/data/FileSystemStyle/Button.qml
new file mode 100644
index 0000000000..a5078b14c2
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/data/FileSystemStyle/Button.qml
@@ -0,0 +1,4 @@
+import QtQuick.Templates as T
+T.Button {
+    objectName: "FileSystemStyle"
+}
diff --git a/tests/auto/quickcontrols2/styleimports/data/FileSystemStyle/qmldir b/tests/auto/quickcontrols2/styleimports/data/FileSystemStyle/qmldir
new file mode 100644
index 0000000000..3c40158832
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/data/FileSystemStyle/qmldir
@@ -0,0 +1,2 @@
+module FileSystemStyle
+Button 2.15 Button.qml
diff --git a/tests/auto/quickcontrols2/styleimports/data/Label.qml b/tests/auto/quickcontrols2/styleimports/data/Label.qml
new file mode 100644
index 0000000000..3959dae8e6
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/data/Label.qml
@@ -0,0 +1,4 @@
+import QtQuick.Templates as T
+T.Label {
+    objectName: "data"
+}
diff --git a/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/+linux/Button.qml b/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/+linux/Button.qml
new file mode 100644
index 0000000000..15c04d7721
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/+linux/Button.qml
@@ -0,0 +1,4 @@
+import QtQuick.Templates as T
+T.Button {
+    objectName: "PlatformStyle/+linux"
+}
diff --git a/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/+macos/Button.qml b/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/+macos/Button.qml
new file mode 100644
index 0000000000..6c07ec028a
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/+macos/Button.qml
@@ -0,0 +1,4 @@
+import QtQuick.Templates as T
+T.Button {
+    objectName: "PlatformStyle/+macos"
+}
diff --git a/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/+windows/Button.qml b/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/+windows/Button.qml
new file mode 100644
index 0000000000..6a94679c2b
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/+windows/Button.qml
@@ -0,0 +1,4 @@
+import QtQuick.Templates as T
+T.Button {
+    objectName: "PlatformStyle/+windows"
+}
diff --git a/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/Button.qml b/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/Button.qml
new file mode 100644
index 0000000000..fce35efdf7
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/Button.qml
@@ -0,0 +1,4 @@
+import QtQuick.Templates as T
+T.Button {
+    objectName: "PlatformStyle/Button.qml"
+}
diff --git a/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/qmldir b/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/qmldir
new file mode 100644
index 0000000000..ce2545171b
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/data/PlatformStyle/qmldir
@@ -0,0 +1,2 @@
+module PlatformStyle
+Button 2.15 Button.qml
diff --git a/tests/auto/quickcontrols2/styleimports/data/applicationWindowWithButton.qml b/tests/auto/quickcontrols2/styleimports/data/applicationWindowWithButton.qml
new file mode 100644
index 0000000000..ba6af22ce9
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/data/applicationWindowWithButton.qml
@@ -0,0 +1,64 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick
+import QtQuick.Controls
+
+ApplicationWindow {
+    title: "Test Application Window"
+    width: 400
+    height: 400
+
+    property alias button: button
+
+    Button {
+        id: button
+    }
+}
diff --git a/tests/auto/quickcontrols2/styleimports/data/qmldir b/tests/auto/quickcontrols2/styleimports/data/qmldir
new file mode 100644
index 0000000000..9e9df9407c
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/data/qmldir
@@ -0,0 +1,4 @@
+module data
+Action 2.15 Action.qml
+Button 2.15 Button.qml
+Label 2.15 Label.qml
diff --git a/tests/auto/quickcontrols2/styleimports/resources/ResourceStyle/Button.qml b/tests/auto/quickcontrols2/styleimports/resources/ResourceStyle/Button.qml
new file mode 100644
index 0000000000..3a97e9de1f
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/resources/ResourceStyle/Button.qml
@@ -0,0 +1,9 @@
+import QtQuick.Controls.impl 2.15
+import QtQuick.Templates 2.15 as T
+T.Button {
+    objectName: "ResourceStyle"
+
+    contentItem: IconLabel {
+        color: "salmon"
+    }
+}
diff --git a/tests/auto/quickcontrols2/styleimports/resources/ResourceStyle/qmldir b/tests/auto/quickcontrols2/styleimports/resources/ResourceStyle/qmldir
new file mode 100644
index 0000000000..4cb1a835bd
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/resources/ResourceStyle/qmldir
@@ -0,0 +1,2 @@
+module ResourceStyle
+Button 2.15 Button.qml
diff --git a/tests/auto/quickcontrols2/styleimports/tst_styleimports.cpp b/tests/auto/quickcontrols2/styleimports/tst_styleimports.cpp
new file mode 100644
index 0000000000..fe5148ed7d
--- /dev/null
+++ b/tests/auto/quickcontrols2/styleimports/tst_styleimports.cpp
@@ -0,0 +1,250 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtCore/qregularexpression.h>
+#include <QtTest/qtest.h>
+#include <QtQml/qqmlcomponent.h>
+#include <QtQml/qqmlcontext.h>
+#include <QtQml/qqmlapplicationengine.h>
+#include <QtQml/qqmlengine.h>
+#include <QtQuick/qquickwindow.h>
+#include <QtQuickControls2/qquickstyle.h>
+#include <QtQuickControls2/private/qquickstyle_p.h>
+#include <QtQuickControls2Impl/private/qquickiconlabel_p.h>
+
+#include "../shared/util.h"
+
+class tst_StyleImports : public QQmlDataTest
+{
+    Q_OBJECT
+
+private slots:
+    void initTestCase() override;
+
+    void cleanup();
+
+    void select_data();
+    void select();
+
+    void platformSelectors();
+
+    void fallbackStyleShouldNotOverwriteTheme_data();
+    void fallbackStyleShouldNotOverwriteTheme();
+};
+
+void tst_StyleImports::initTestCase()
+{
+    QQmlDataTest::initTestCase();
+}
+
+void tst_StyleImports::cleanup()
+{
+    qmlClearTypeRegistrations();
+}
+
+void tst_StyleImports::select_data()
+{
+    QTest::addColumn<QString>("file");
+    QTest::addColumn<QString>("style");
+    QTest::addColumn<QString>("fallback");
+    QTest::addColumn<QString>("expected");
+
+    // Action.qml exists in the "data" style and the Basic style.
+    QTest::newRow("control=Action,style=basic,fallback=empty") << "Action.qml" << "Basic" << "" << "Basic";
+    QTest::newRow("control=Action,style=fs,fallback=empty") << "Action.qml" << "FileSystemStyle" << "" << "Basic";
+    QTest::newRow("control=Action,style=qrc,fallback=empty") << "Action.qml" << "ResourceStyle" << "" << "Basic";
+    QTest::newRow("control=Action,style=nosuch,fallback=empty") << "Action.qml" << "NoSuchStyle" << "" << "Basic";
+    QTest::newRow("control=Action,style=data,fallback=empty") << "Action.qml" << "data" << "" << "data";
+
+    QTest::newRow("control=Action,style=basic,fallback=mat") << "Action.qml" << "Basic" << "Material" << "";
+    QTest::newRow("control=Action,style=fs,fallback=mat") << "Action.qml" << "FileSystemStyle" << "Material" << "Basic";
+    QTest::newRow("control=Action,style=qrc,fallback=mat") << "Action.qml" << "ResourceStyle" << "Material" << "Basic";
+    QTest::newRow("control=Action,style=nosuch,fallback=mat") << "Action.qml" << "NoSuchStyle" << "Material" << "Basic";
+    QTest::newRow("control=Action,style=data,fallback=mat") << "Action.qml" << "data" << "Material" << "data";
+
+    // Amongst the styles we're testing here, ScrollView.qml only exists in the Basic style.
+    QTest::newRow("control=ScrollView,style=basic,fallback=empty") << "ScrollView.qml" << "Basic" << "" << "Basic";
+    QTest::newRow("control=ScrollView,style=fs,fallback=empty") << "ScrollView.qml" << "FileSystemStyle" << "" << "Basic";
+    QTest::newRow("control=ScrollView,style=qrc,fallback=empty") << "ScrollView.qml" << "ResourceStyle" << "" << "Basic";
+    QTest::newRow("control=ScrollView,style=nosuch,fallback=empty") << "ScrollView.qml" << "NoSuchStyle" << "" << "Basic";
+    QTest::newRow("control=ScrollView,style=data,fallback=empty") << "ScrollView.qml" << "data" << "" << "Basic";
+
+    QTest::newRow("control=ScrollView,style=basic,fallback=mat") << "ScrollView.qml" << "Basic" << "Material" << "Basic";
+    QTest::newRow("control=ScrollView,style=fs,fallback=mat") << "ScrollView.qml" << "FileSystemStyle" << "Material" << "Basic";
+    QTest::newRow("control=ScrollView,style=qrc,fallback=mat") << "ScrollView.qml" << "ResourceStyle" << "Material" << "Basic";
+    QTest::newRow("control=ScrollView,style=nosuch,fallback=mat") << "ScrollView.qml" << "NoSuchStyle" << "Material" << "Basic";
+    QTest::newRow("control=ScrollView,style=data,fallback=mat") << "ScrollView.qml" << "data" << "Material" << "Basic";
+
+    // Label.qml exists in the "data", Basic and Material styles.
+    QTest::newRow("control=Label,style=basic,fallback=empty") << "Label.qml" << "Basic" << "" << "Basic";
+    QTest::newRow("control=Label,style=fs,fallback=empty") << "Label.qml" << "FileSystemStyle" << "" << "Basic";
+    QTest::newRow("control=Label,style=qrc,fallback=empty") << "Label.qml" << "ResourceStyle" << "" << "Basic";
+    QTest::newRow("control=Label,style=nosuch,fallback=empty") << "Label.qml" << "NoSuchStyle" << "" << "Basic";
+    QTest::newRow("control=Label,style=data,fallback=empty") << "Label.qml" << "data" << "" << "data";
+
+    QTest::newRow("control=Label,style=basic,fallback=mat") << "Label.qml" << "Basic" << "Material" << "Basic";
+    QTest::newRow("control=Label,style=fs,fallback=mat") << "Label.qml" << "FileSystemStyle" << "Material" << "Basic";
+    QTest::newRow("control=Label,style=qrc,fallback=mat") << "Label.qml" << "ResourceStyle" << "Material" << "Basic";
+    QTest::newRow("control=Label,style=nosuch,fallback=mat") << "Label.qml" << "NoSuchStyle" << "Material" << "Basic";
+    QTest::newRow("control=Label,style=data,fallback=mat") << "Label.qml" << "data" << "Material" << "data";
+
+    // Button.qml exists in all styles including the fs and qrc styles
+    QTest::newRow("control=Button,style=basic,fallback=empty") << "Button.qml" << "Basic" << "" << "Basic";
+    QTest::newRow("control=Button,style=fs,fallback=empty") << "Button.qml" << "FileSystemStyle" << "" << "FileSystemStyle";
+    QTest::newRow("control=Button,style=qrc,fallback=empty") << "Button.qml" << "ResourceStyle" << "" << "ResourceStyle";
+    QTest::newRow("control=Button,style=nosuch,fallback=empty") << "Button.qml" << "NoSuchStyle" << "" << "Basic";
+    QTest::newRow("control=Button,style=data,fallback=empty") << "Button.qml" << "data" << "" << "data";
+
+    QTest::newRow("control=Button,style=basic,fallback=mat") << "Button.qml" << "Basic" << "Material" << "Basic";
+    QTest::newRow("control=Button,style=fs,fallback=mat") << "Button.qml" << "FileSystemStyle" << "Material" << "FileSystemStyle";
+    QTest::newRow("control=Button,style=qrc,fallback=mat") << "Button.qml" << "ResourceStyle" << "Material" << "ResourceStyle";
+    QTest::newRow("control=Button,style=nosuch,fallback=mat") << "Button.qml" << "NoSuchStyle" << "Material" << "Basic";
+    QTest::newRow("control=Button,style=data,fallback=mat") << "Button.qml" << "data" << "Material" << "data";
+}
+
+void tst_StyleImports::select()
+{
+    QFETCH(QString, file);
+    QFETCH(QString, style);
+    QFETCH(QString, fallback);
+    QFETCH(QString, expected);
+
+    // In Qt 5, there were several accepted forms for style names.
+    // In Qt 6, the only accepted form is the base name of the style directory.
+    const bool invalidStyleName = style.contains(QLatin1Char('/'));
+    if (invalidStyleName)
+        QTest::ignoreMessage(QtWarningMsg,
+            "Style names must not contain paths; see the \"Definition of a Style\" documentation for more information");
+    QQuickStyle::setStyle(style);
+    QQuickStyle::setFallbackStyle(fallback);
+
+    QQmlEngine engine;
+    engine.addImportPath(QLatin1String(":/"));
+    engine.addImportPath(directory());
+    engine.addImportPath(dataDirectory());
+    QQmlComponent component(&engine);
+    const QString controlName = file.mid(0, file.indexOf(QLatin1Char('.')));
+    component.setData(QString::fromLatin1("import QtQuick; import QtQuick.Controls; %1 { }").arg(controlName).toUtf8(), QUrl());
+
+    const bool nonExistentStyle = style == QLatin1String("NoSuchStyle");
+    if (nonExistentStyle)
+        QTest::ignoreMessage(QtWarningMsg, "QQmlComponent: Component is not ready");
+    QScopedPointer<QObject> object(component.create());
+    if (nonExistentStyle) {
+        QVERIFY(object.isNull());
+        return;
+    }
+
+    QVERIFY2(!object.isNull(), qPrintable(component.errorString()));
+
+    // TODO: test built-in styles below too
+    // We can't check for the attached style object since that API is in a plugin,
+    // and it's not possible to use e.g. the baseUrl of the QQmlContext
+    // nor the metaObject to test it either.
+
+    if (!QQuickStylePrivate::builtInStyles().contains(expected)) {
+        // We're expecting a custom style.
+        QCOMPARE(object->objectName(), expected);
+    }
+}
+
+void tst_StyleImports::platformSelectors()
+{
+    QQuickStyle::setStyle(QLatin1String("PlatformStyle"));
+
+    QQmlApplicationEngine engine;
+    engine.addImportPath(dataDirectory());
+    engine.load(testFileUrl("applicationWindowWithButton.qml"));
+    QQuickWindow *window = qobject_cast<QQuickWindow*>(engine.rootObjects().first());
+    QVERIFY(window);
+
+    QObject *button = window->property("button").value<QObject*>();
+    QVERIFY(button);
+
+#if defined(Q_OS_LINUX)
+    QCOMPARE(button->objectName(), "PlatformStyle/+linux");
+#elif defined(Q_OS_MACOS)
+    QCOMPARE(button->objectName(), "PlatformStyle/+macos");
+#elif defined(Q_OS_WIN)
+    QCOMPARE(button->objectName(), "PlatformStyle/+windows");
+#else
+    QCOMPARE(button->objectName(), "PlatformStyle/Button.qml");
+#endif
+}
+
+void tst_StyleImports::fallbackStyleShouldNotOverwriteTheme_data()
+{
+    QTest::addColumn<QString>("style");
+    QTest::addColumn<QString>("fallbackStyle");
+    QTest::addColumn<QColor>("expectedContentItemColor");
+
+    QTest::addRow("style=Fusion,fallbackStyle=Material")
+        << QString::fromLatin1("Fusion") << QString::fromLatin1("Material") << QColor::fromRgb(0x252525);
+    QTest::addRow("style=ResourceStyle,fallbackStyle=Material")
+        << QString::fromLatin1("ResourceStyle") << QString::fromLatin1("Material") << QColor("salmon");
+}
+
+void tst_StyleImports::fallbackStyleShouldNotOverwriteTheme()
+{
+    QFETCH(QString, style);
+    QFETCH(QString, fallbackStyle);
+    QFETCH(QColor, expectedContentItemColor);
+
+    QQuickStyle::setStyle(style);
+    QQuickStyle::setFallbackStyle(fallbackStyle);
+
+    QQmlApplicationEngine engine;
+    engine.addImportPath(QLatin1String(":/"));
+    engine.addImportPath(dataDirectory());
+    engine.load(testFileUrl("applicationWindowWithButton.qml"));
+    QVERIFY(!engine.rootObjects().isEmpty());
+    QQuickWindow *window = qobject_cast<QQuickWindow*>(engine.rootObjects().first());
+    QVERIFY(window);
+
+    QObject *button = window->property("button").value<QObject*>();
+    QVERIFY(button);
+
+    QQuickIconLabel *contentItem = button->property("contentItem").value<QQuickIconLabel*>();
+    QVERIFY(contentItem);
+
+    // For example: the Fusion style provides Button.qml, so the Button's text color
+    // should be that of QPalette::ButtonText from QQuickFusionTheme.
+    QCOMPARE(contentItem->color(), expectedContentItemColor);
+}
+
+QTEST_MAIN(tst_StyleImports)
+
+#include "tst_styleimports.moc"