QLatin1String: add test

QLatin1String wasn't really tested except as a drive-by.
Unearthed a discrepancy with docs. Fixed the docs.

Change-Id: I1246bb33888132edbc4e22da792a480a156357bf
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

5 files changed, 127 insertions, 5 deletions

diff --git a/src/corelib/tools/qstring.cpp b/src/corelib/tools/qstring.cpp
index ea220ed557..38b5dcfe1f 100644
--- a/src/corelib/tools/qstring.cpp
+++ b/src/corelib/tools/qstring.cpp
@@ -8227,9 +8227,7 @@ QString &QString::setRawData(const QChar *unicode, int size)
 
 /*! \fn QLatin1String::QLatin1String(const char *str)
 
-    Constructs a QLatin1String object that stores \a str. Note that if
-    \a str is 0, an empty string is created; this case is handled by
-    QString.
+    Constructs a QLatin1String object that stores \a str.
 
     The string data is \e not copied. The caller must be able to
     guarantee that \a str will not be deleted or modified as long as
@@ -8241,8 +8239,6 @@ QString &QString::setRawData(const QChar *unicode, int size)
 /*! \fn QLatin1String::QLatin1String(const char *str, int size)
 
     Constructs a QLatin1String object that stores \a str with \a size.
-    Note that if \a str is 0, an empty string is created; this case
-    is handled by QString.
 
     The string data is \e not copied. The caller must be able to
     guarantee that \a str will not be deleted or modified as long as
diff --git a/tests/auto/corelib/tools/qlatin1string/.gitignore b/tests/auto/corelib/tools/qlatin1string/.gitignore
new file mode 100644
index 0000000000..dddf56b2df
--- /dev/null
+++ b/tests/auto/corelib/tools/qlatin1string/.gitignore
@@ -0,0 +1 @@
+tst_qlatin1string
diff --git a/tests/auto/corelib/tools/qlatin1string/qlatin1string.pro b/tests/auto/corelib/tools/qlatin1string/qlatin1string.pro
new file mode 100644
index 0000000000..219afa661b
--- /dev/null
+++ b/tests/auto/corelib/tools/qlatin1string/qlatin1string.pro
@@ -0,0 +1,8 @@
+CONFIG += testcase parallel_test
+TARGET = tst_qlatin1string
+QT = core testlib
+SOURCES = tst_qlatin1string.cpp
+DEFINES += QT_NO_CAST_TO_ASCII
+contains(QT_CONFIG,c++11): CONFIG += c++11 c++14
+
+DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0
diff --git a/tests/auto/corelib/tools/qlatin1string/tst_qlatin1string.cpp b/tests/auto/corelib/tools/qlatin1string/tst_qlatin1string.cpp
new file mode 100644
index 0000000000..5b83fe1958
--- /dev/null
+++ b/tests/auto/corelib/tools/qlatin1string/tst_qlatin1string.cpp
@@ -0,0 +1,116 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** 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 http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtTest/QtTest>
+
+#include <QString>
+
+class tst_QLatin1String : public QObject
+{
+    Q_OBJECT
+
+private Q_SLOTS:
+    void nullString();
+    void emptyString();
+};
+
+void tst_QLatin1String::nullString()
+{
+    // from nullptr
+    {
+        const char *null = Q_NULLPTR;
+        QLatin1String l1(null);
+        QCOMPARE(static_cast<const void*>(l1.data()), static_cast<const void*>(Q_NULLPTR));
+        QCOMPARE(l1.size(), 0);
+
+        QString s = l1;
+        QVERIFY(s.isNull());
+    }
+
+    // from null QByteArray
+    {
+        const QByteArray null;
+        QVERIFY(null.isNull());
+
+        QLatin1String l1(null);
+        QEXPECT_FAIL("", "null QByteArrays become non-null QLatin1Strings...", Continue);
+        QCOMPARE(static_cast<const void*>(l1.data()), static_cast<const void*>(Q_NULLPTR));
+        QCOMPARE(l1.size(), 0);
+
+        QString s = l1;
+        QEXPECT_FAIL("", "null QByteArrays become non-null QLatin1Strings become non-null QStrings...", Continue);
+        QVERIFY(s.isNull());
+    }
+}
+
+void tst_QLatin1String::emptyString()
+{
+    {
+        const char *empty = "";
+        QLatin1String l1(empty);
+        QCOMPARE(static_cast<const void*>(l1.data()), static_cast<const void*>(empty));
+        QCOMPARE(l1.size(), 0);
+
+        QString s = l1;
+        QVERIFY(s.isEmpty());
+        QVERIFY(!s.isNull());
+    }
+
+    {
+        const char *notEmpty = "foo";
+        QLatin1String l1(notEmpty, 0);
+        QCOMPARE(static_cast<const void*>(l1.data()), static_cast<const void*>(notEmpty));
+        QCOMPARE(l1.size(), 0);
+
+        QString s = l1;
+        QVERIFY(s.isEmpty());
+        QVERIFY(!s.isNull());
+    }
+
+    {
+        const QByteArray empty = "";
+        QLatin1String l1(empty);
+        QCOMPARE(static_cast<const void*>(l1.data()), static_cast<const void*>(empty.constData()));
+        QCOMPARE(l1.size(), 0);
+
+        QString s = l1;
+        QVERIFY(s.isEmpty());
+        QVERIFY(!s.isNull());
+    }
+}
+
+
+
+QTEST_APPLESS_MAIN(tst_QLatin1String)
+
+#include "tst_qlatin1string.moc"
diff --git a/tests/auto/corelib/tools/tools.pro b/tests/auto/corelib/tools/tools.pro
index 9024a1a1bb..f9e1c454e7 100644
--- a/tests/auto/corelib/tools/tools.pro
+++ b/tests/auto/corelib/tools/tools.pro
@@ -24,6 +24,7 @@ SUBDIRS=\
     qhash \
     qhash_strictiterators \
     qhashfunctions \
+    qlatin1string \
     qline \
     qlinkedlist \
     qlist \