QQuickComboBox: emit countChanged signal when model is updated

[ChangeLog][QtQuick][QQuickComboBox] countChanged signal now will be
emitted when a new model is set to the ComboBox

Fixes: QTBUG-75972
Change-Id: Ic26718453ba06ba284ac5903fc6f55ddf3523331
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

3 files changed, 97 insertions, 0 deletions

diff --git a/src/quicktemplates2/qquickcombobox.cpp b/src/quicktemplates2/qquickcombobox.cpp
index 78ec7ef8..0fa6298f 100644
--- a/src/quicktemplates2/qquickcombobox.cpp
+++ b/src/quicktemplates2/qquickcombobox.cpp
@@ -828,6 +828,7 @@ void QQuickComboBox::setModel(const QVariant& m)
 
     d->model = model;
     d->createDelegateModel();
+    emit countChanged();
     if (isComponentComplete()) {
         setCurrentIndex(count() > 0 ? 0 : -1);
         d->updateCurrentText();
diff --git a/tests/auto/qquickpopup/data/countChanged.qml b/tests/auto/qquickpopup/data/countChanged.qml
new file mode 100644
index 00000000..ee5876d7
--- /dev/null
+++ b/tests/auto/qquickpopup/data/countChanged.qml
@@ -0,0 +1,80 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 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 2.12
+import QtQuick.Window 2.12
+import QtQuick.Controls 2.12
+
+Window {
+    width: 640
+    height: 480
+    property bool isModel1: true
+    property alias comboBox: comboBox
+    property int count: comboBox.count
+    ListModel {
+        id: model1
+        ListElement {
+            display: "one"
+        }
+    }
+    ListModel {
+        id: model2
+        ListElement {
+            display: "one"
+        }
+        ListElement {
+            display: "two"
+        }
+    }
+    ComboBox {
+        id: comboBox
+        model: isModel1 ? model1 : model2
+    }
+}
diff --git a/tests/auto/qquickpopup/tst_qquickpopup.cpp b/tests/auto/qquickpopup/tst_qquickpopup.cpp
index 81b2d583..c2f876b8 100644
--- a/tests/auto/qquickpopup/tst_qquickpopup.cpp
+++ b/tests/auto/qquickpopup/tst_qquickpopup.cpp
@@ -88,6 +88,7 @@ private slots:
     void qquickview();
     void disabledPalette();
     void disabledParentPalette();
+    void countChanged();
 };
 
 void tst_QQuickPopup::initTestCase()
@@ -1171,6 +1172,21 @@ void tst_QQuickPopup::disabledParentPalette()
     QTRY_VERIFY(!popup->isVisible());
 }
 
+void tst_QQuickPopup::countChanged()
+{
+    QQuickApplicationHelper helper(this, "countChanged.qml");
+
+    QQuickWindow *window = helper.window;
+    window->show();
+    QVERIFY(QTest::qWaitForWindowActive(window));
+
+    QQuickComboBox *comboBox = window->property("comboBox").value<QQuickComboBox*>();
+    QVERIFY(comboBox);
+    QCOMPARE(window->property("count").toInt(), 1);
+
+    QVERIFY(window->setProperty("isModel1", false));
+    QTRY_COMPARE(window->property("count").toInt(), 2);
+}
 QTEST_QUICKCONTROLS_MAIN(tst_QQuickPopup)
 
 #include "tst_qquickpopup.moc"