Ensure QTextStream doesn't modify the Text flag on the underlying iodevice

An empty read or a failed write on the underlying QIODevice of the text
stream would lead to an early return where we wouldn't correctly restore
the QIODevice::Text flag of the io device.

Change-Id: I5b632f45dea6ede3f408113556c3dad1b96574e2
Task-number: QTBUG-47176
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/tests/auto/corelib/io/qtextstream/tst_qtextstream.cpp b/tests/auto/corelib/io/qtextstream/tst_qtextstream.cpp
index 3ab53848d8..a0348f3c54 100644
--- a/tests/auto/corelib/io/qtextstream/tst_qtextstream.cpp
+++ b/tests/auto/corelib/io/qtextstream/tst_qtextstream.cpp
@@ -228,6 +228,8 @@ private slots:
     void alignAccountingStyle();
     void setCodec();
 
+    void textModeOnEmptyRead();
+
 private:
     void generateLineData(bool for_QString);
     void generateAllData(bool for_QString);
@@ -3045,6 +3047,21 @@ void tst_QTextStream::int_write_with_locale()
     QCOMPARE(result, output);
 }
 
+void tst_QTextStream::textModeOnEmptyRead()
+{
+    const QString filename("textmodetest.txt");
+    QFile::remove(filename); // Remove file if exists
+
+
+    QFile file(filename);
+    QVERIFY(file.open(QIODevice::ReadWrite | QIODevice::Text));
+    QTextStream stream(&file);
+    QVERIFY(file.isTextModeEnabled());
+    QString emptyLine = stream.readLine(); // Text mode flag cleared here
+    QVERIFY(file.isTextModeEnabled());
+}
+
+
 // ------------------------------------------------------------------------------
 
 QTEST_MAIN(tst_QTextStream)