Ensure that C++ Qt Quick tests are run with all applicable styles

Since 8b534487044dfb3b464431ecb91ef4e0864af4ed, the C++ tests were only
being run with the default style for the platform that they were run
on.

Fix this by keeping track of whether a default style is in use and
checking it in the tests.

Pick-to: 6.0
Change-Id: I4ddd90aba12ede83fff0d3d1002534e79fce8c87
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

4 files changed, 23 insertions, 1 deletions

diff --git a/src/quickcontrols2/qquickstyle.cpp b/src/quickcontrols2/qquickstyle.cpp
index f4e1da00..7c403529 100644
--- a/src/quickcontrols2/qquickstyle.cpp
+++ b/src/quickcontrols2/qquickstyle.cpp
@@ -184,7 +184,10 @@ struct QQuickStyleSpec
         // Find the config file.
         resolveConfigFilePath();
 
+        usingDefaultStyle = false;
+
         if (style.isEmpty() || style.toLower() == QStringLiteral("default")) {
+            usingDefaultStyle = true;
             style.clear();
 
             qCDebug(lcQtQuickControlsStyle) << "no style (or Default) was specified;"
@@ -226,6 +229,7 @@ struct QQuickStyleSpec
 
         custom = false;
         resolved = false;
+        usingDefaultStyle = false;
         style.clear();
         fallbackStyle.clear();
         fallbackMethod.clear();
@@ -250,6 +254,8 @@ struct QQuickStyleSpec
     bool custom = false;
     // Have we resolved the style yet?
     bool resolved = false;
+    // Are we using the default style for this platform (because no style was specified)?
+    bool usingDefaultStyle = false;
     // The name of the style.
     QString style;
     // The built-in style to use if the requested style cannot be found.
@@ -262,6 +268,11 @@ struct QQuickStyleSpec
 
 Q_GLOBAL_STATIC(QQuickStyleSpec, styleSpec)
 
+/*
+    Note that most of these functions (with the exception of e.g. isResolved())
+    should not be called before the style has been resolved, as it's only after
+    that happens that they will have been set.
+*/
 QString QQuickStylePrivate::style()
 {
     return styleSpec()->style;
@@ -287,6 +298,11 @@ bool QQuickStylePrivate::isResolved()
     return styleSpec()->resolved;
 }
 
+bool QQuickStylePrivate::isUsingDefaultStyle()
+{
+    return styleSpec()->usingDefaultStyle;
+}
+
 void QQuickStylePrivate::init()
 {
     QQuickStyleSpec *spec = styleSpec();
diff --git a/src/quickcontrols2/qquickstyle_p.h b/src/quickcontrols2/qquickstyle_p.h
index 8d0e5a8d..31c70893 100644
--- a/src/quickcontrols2/qquickstyle_p.h
+++ b/src/quickcontrols2/qquickstyle_p.h
@@ -63,6 +63,7 @@ public:
     static QString fallbackStyle();
     static bool isCustomStyle();
     static bool isResolved();
+    static bool isUsingDefaultStyle();
     static bool exists();
     static void init();
     static void reset();
diff --git a/tests/auto/qquickstyle/tst_qquickstyle.cpp b/tests/auto/qquickstyle/tst_qquickstyle.cpp
index b9497500..97259051 100644
--- a/tests/auto/qquickstyle/tst_qquickstyle.cpp
+++ b/tests/auto/qquickstyle/tst_qquickstyle.cpp
@@ -137,6 +137,7 @@ void tst_QQuickStyle::configurationFile()
     QVERIFY2(!object.isNull(), qPrintable(labelComponent.errorString()));
 
     QCOMPARE(QQuickStyle::name(), expectedStyle);
+    QVERIFY(!QQuickStylePrivate::isUsingDefaultStyle());
 
     // Test that fonts and palettes specified in configuration files are respected.
     QQuickLabel *label = qobject_cast<QQuickLabel *>(object.data());
diff --git a/tests/auto/shared/qtest_quickcontrols.h b/tests/auto/shared/qtest_quickcontrols.h
index acd0304c..8eadd979 100644
--- a/tests/auto/shared/qtest_quickcontrols.h
+++ b/tests/auto/shared/qtest_quickcontrols.h
@@ -46,7 +46,11 @@
 
 static QStringList testStyles()
 {
-    if (QQuickStyle::name().isEmpty())
+    // It's not enough to check if the name is empty, because since Qt 6
+    // we set an appropriate style for the platform if no style was specified.
+    // Also, we need the name check to come first, as isUsingDefaultStyle() does not do any resolving,
+    // and so its return value wouldn't be correct otherwise.
+    if (QQuickStyle::name().isEmpty() || QQuickStylePrivate::isUsingDefaultStyle())
         return QQuickStylePrivate::builtInStyles();
     return QStringList(QQuickStyle::name());
 }