Implement a dedicated QAccessibleInterface for QMessageBox

QMessageBox has text values that an accessible client should be able to
read directly without having to navigate through the text labels.

Add test coverage.

Windows Narrator is inconsistent in reading the contents of a message
box. It might skip them completely, even though the text property is
read through the interface.

Task-number: QTBUG-101585
Change-Id: I639c2210a627733c093743790c6a6b83f4bb80d0
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>
(cherry picked from commit 56d6a360206c7bd93e6503a63daf1517ff40a1d4)
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

src/widgets/accessible/qaccessiblewidgetfactory.cpp

@@ -85,7 +85,7 @@ QAccessibleInterface *qAccessibleFactory(const QString &classname, QObject *obje
     } else if (classname == "QDialog"_L1) {
         iface = new QAccessibleWidget(widget, QAccessible::Dialog);
     } else if (classname == "QMessageBox"_L1) {
-        iface = new QAccessibleWidget(widget, QAccessible::AlertMessage);
+        iface = new QAccessibleMessageBox(widget);
 #if QT_CONFIG(mainwindow)
     } else if (classname == "QMainWindow"_L1) {
         iface = new QAccessibleMainWindow(widget);

src/widgets/accessible/simplewidgets.cpp

@@ -43,6 +43,8 @@
 #ifndef QT_NO_PICTURE
 #include <QtGui/qpicture.h>
 #endif
+#include <qmessagebox.h>
+#include <qdialogbuttonbox.h>
 #include <qstyle.h>
 #include <qstyleoption.h>
 #include <qtextdocument.h>
@@ -951,6 +953,47 @@ QWindowContainer *QAccessibleWindowContainer::container() const
     return static_cast<QWindowContainer *>(widget());
 }
 
+/*!
+    \internal
+    Implements QAccessibleWidget for QMessageBox
+*/
+QAccessibleMessageBox::QAccessibleMessageBox(QWidget *widget)
+    : QAccessibleWidget(widget, QAccessible::AlertMessage)
+{
+    Q_ASSERT(qobject_cast<QMessageBox *>(widget));
+}
+
+QMessageBox *QAccessibleMessageBox::messageBox() const
+{
+    return static_cast<QMessageBox *>(widget());
+}
+
+QString QAccessibleMessageBox::text(QAccessible::Text t) const
+{
+    QString str;
+
+    switch (t) {
+    case QAccessible::Name:
+        str = QAccessibleWidget::text(t);
+        if (str.isEmpty()) // implies no title text is set
+            str = messageBox()->text();
+        break;
+    case QAccessible::Description:
+        str = widget()->accessibleDescription();
+        break;
+    case QAccessible::Value:
+        str = messageBox()->text();
+        break;
+    case QAccessible::Help:
+        str = messageBox()->informativeText();
+        break;
+    default:
+        break;
+    }
+
+    return str;
+}
+
 #endif // QT_CONFIG(accessibility)
 
 QT_END_NAMESPACE

src/widgets/accessible/simplewidgets_p.h

@@ -27,6 +27,7 @@ class QAbstractButton;
 class QLineEdit;
 class QToolButton;
 class QGroupBox;
+class QMessageBox;
 class QProgressBar;
 
 #if QT_CONFIG(abstractbutton)
@@ -189,6 +190,16 @@ private:
     QWindowContainer *container() const;
 };
 
+class QAccessibleMessageBox : public QAccessibleWidget
+{
+public:
+    explicit QAccessibleMessageBox(QWidget *widget);
+
+    QString text(QAccessible::Text t) const override;
+
+    QMessageBox *messageBox() const;
+};
+
 #endif // QT_CONFIG(accessibility)
 
 QT_END_NAMESPACE

tests/auto/other/qaccessibility/tst_qaccessibility.cpp

@@ -21,6 +21,8 @@
 #include <QtGui/private/qguiapplication_p.h>
 #include <QtGui/private/qhighdpiscaling_p.h>
 
+#include <QtWidgets/private/qdialog_p.h>
+
 #if defined(Q_OS_WIN) && defined(interface)
 #   undef interface
 #endif
@@ -219,6 +221,9 @@ private slots:
     void bridgeTest();
     void focusChild();
 
+    void messageBoxTest_data();
+    void messageBoxTest();
+
 protected slots:
     void onClicked();
 private:
@@ -4196,6 +4201,105 @@ void tst_QAccessibility::focusChild()
     }
 }
 
+void tst_QAccessibility::messageBoxTest_data()
+{
+    QTest::addColumn<QMessageBox::Icon>("icon");
+    QTest::addColumn<QMessageBox::StandardButtons>("buttons");
+    QTest::addColumn<QString>("title");
+    QTest::addColumn<QString>("text");
+    QTest::addColumn<QString>("infoText");
+    QTest::addColumn<QString>("details");
+    QTest::addColumn<bool>("checkbox");
+    QTest::addColumn<bool>("textInteractive");
+
+    QTest::addRow("Information") << QMessageBox::Information
+                                 << QMessageBox::StandardButtons(QMessageBox::Ok)
+                                 << "Information"
+                                 << "Here, have some information."
+                                 << QString()
+                                 << QString()
+                                 << false
+                                 << false;
+
+    QTest::addRow("Warning") << QMessageBox::Warning
+                                 << QMessageBox::StandardButtons(QMessageBox::Ok | QMessageBox::Cancel)
+                                 << "Warning"
+                                 << "This is a dangerous operation!"
+                                 << "Ok or Cancel?"
+                                 << QString()
+                                 << true
+                                 << false;
+
+    QTest::addRow("Error") << QMessageBox::Critical
+                                 << QMessageBox::StandardButtons(QMessageBox::Abort | QMessageBox::Retry | QMessageBox::Ignore)
+                                 << "Error"
+                                 << "Operation failed for http://example.com"
+                                 << "You have to decide what to do"
+                                 << "Detailed log output"
+                                 << false
+                                 << true;
+}
+
+void tst_QAccessibility::messageBoxTest()
+{
+    QFETCH(QMessageBox::Icon, icon);
+    QFETCH(QMessageBox::StandardButtons, buttons);
+    QFETCH(QString, title);
+    QFETCH(QString, text);
+    QFETCH(QString, infoText);
+    QFETCH(QString, details);
+    QFETCH(bool, checkbox);
+    QFETCH(bool, textInteractive);
+
+    QMessageBox box(icon, title, text, buttons);
+
+    QAccessibleInterface *iface = QAccessible::queryAccessibleInterface(&box);
+    QVERIFY(iface);
+    QCOMPARE(iface->role(), QAccessible::AlertMessage);
+#ifndef Q_OS_DARWIN // macOS message boxes show no title
+    QCOMPARE(iface->text(QAccessible::Name), title);
+#endif
+    QCOMPARE(iface->text(QAccessible::Value), text);
+
+    int expectedChildCount = 3;
+    QCOMPARE(iface->childCount(), expectedChildCount);
+
+    if (textInteractive)
+        box.setTextInteractionFlags(Qt::TextBrowserInteraction);
+
+    if (!infoText.isEmpty()) {
+        box.setInformativeText(infoText);
+        QCOMPARE(iface->childCount(), ++expectedChildCount);
+    }
+    QCOMPARE(iface->text(QAccessible::Help), infoText);
+
+    if (!details.isEmpty()) {
+        box.setDetailedText(details);
+        QCOMPARE(iface->childCount(), ++expectedChildCount);
+    }
+    if (checkbox) {
+        box.setCheckBox(new QCheckBox("Don't show again"));
+        QCOMPARE(iface->childCount(), ++expectedChildCount);
+    }
+
+    QTestAccessibility::clearEvents();
+
+    QDialogPrivate *boxPrivate = static_cast<QDialogPrivate *>(QDialogPrivate::get(&box));
+    if (!boxPrivate->canBeNativeDialog()) {
+        // platforms that use a native message box will not emit accessibility events
+        box.show();
+
+        QAccessibleEvent showEvent(&box, QAccessible::DialogStart);
+        QVERIFY(QTestAccessibility::containsEvent(&showEvent));
+
+        box.hide();
+
+        QAccessibleEvent hideEvent(&box, QAccessible::DialogEnd);
+        QVERIFY(QTestAccessibility::containsEvent(&hideEvent));
+    }
+
+    QTestAccessibility::clearEvents();
+}
 
 QTEST_MAIN(tst_QAccessibility)
 #include "tst_qaccessibility.moc"