Fix QStringListModel::setData to check for actual changes

QStringListModel::setData documentation states that
"The dataChanged() signal is emitted if the item is changed."
This patch actually respects the doc. setData will check that the data
actually changed before sending the dataChanged signal.

[ChangeLog][QtCore][QStringListModel] setData will now emit the
dataChanged() signal only if the string set is different from
the one already contained in the model

Change-Id: I4308a6f3b4851203fb899c5e29a36076e0c32f2f
Reviewed-by: David Faure <david.faure@kdab.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/tests/auto/corelib/itemmodels/qstringlistmodel/tst_qstringlistmodel.cpp b/tests/auto/corelib/itemmodels/qstringlistmodel/tst_qstringlistmodel.cpp
index 9a54c0a70d..1b40e77648 100644
--- a/tests/auto/corelib/itemmodels/qstringlistmodel/tst_qstringlistmodel.cpp
+++ b/tests/auto/corelib/itemmodels/qstringlistmodel/tst_qstringlistmodel.cpp
@@ -81,6 +81,8 @@ private slots:
     void setData_emits_both_roles_data();
     void setData_emits_both_roles();
 
+    void setData_emits_on_change_only();
+
     void supportedDragDropActions();
 };
 
@@ -246,6 +248,24 @@ void tst_QStringListModel::setData_emits_both_roles()
              expected);
 }
 
+void tst_QStringListModel::setData_emits_on_change_only()
+{
+    QStringListModel model(QStringList{QStringLiteral("one"), QStringLiteral("two")});
+    QSignalSpy dataChangedSpy(&model, &QAbstractItemModel::dataChanged);
+    QVERIFY(dataChangedSpy.isValid());
+    const QModelIndex modelIdx = model.index(0, 0);
+    const QString newStringData = QStringLiteral("test");
+    QVERIFY(model.setData(modelIdx, newStringData));
+    QCOMPARE(dataChangedSpy.count(), 1);
+    const QList<QVariant> spyList = dataChangedSpy.takeFirst();
+    QCOMPARE(spyList.at(0).value<QModelIndex>(), modelIdx);
+    QCOMPARE(spyList.at(1).value<QModelIndex>(), modelIdx);
+    const QVector<int> expectedRoles{Qt::DisplayRole, Qt::EditRole};
+    QCOMPARE(spyList.at(2).value<QVector<int> >(), expectedRoles);
+    QVERIFY(model.setData(modelIdx, newStringData));
+    QVERIFY(dataChangedSpy.isEmpty());
+}
+
 void tst_QStringListModel::supportedDragDropActions()
 {
     QStringListModel model;