QCommandLineParser: pluck some low-hanging fruit re: exception safety

Make
  QCommandLineParser::add{Help,Version}Option()
  QCommandLineOption::setDefaultValue()
  QCommandLineOptionPrivate::setNames()
have transaction semantics: either they succeed, or they change nothing.
It's trivial to provide this guarantee, so do it.

Add a test for the surprising property that setDefaultValue("") resets
defaultValues() to an empty QStringList instead of one that contains
the empty string.

Change-Id: I61623019de3c7d2e52c24f42cc2e23ec5fddc4da
Reviewed-by: David Faure <david.faure@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/tests/auto/corelib/tools/qcommandlineparser/tst_qcommandlineparser.cpp b/tests/auto/corelib/tools/qcommandlineparser/tst_qcommandlineparser.cpp
index f37e192ad3..d111c53551 100644
--- a/tests/auto/corelib/tools/qcommandlineparser/tst_qcommandlineparser.cpp
+++ b/tests/auto/corelib/tools/qcommandlineparser/tst_qcommandlineparser.cpp
@@ -69,6 +69,7 @@ private slots:
     void testUnknownOptionErrorHandling();
     void testDoubleDash_data();
     void testDoubleDash();
+    void testDefaultValue();
     void testProcessNotCalled();
     void testEmptyArgsList();
     void testMissingOptionValue();
@@ -322,6 +323,17 @@ void tst_QCommandLineParser::testDoubleDash()
     QCOMPARE(parser.unknownOptionNames(), QStringList());
 }
 
+void tst_QCommandLineParser::testDefaultValue()
+{
+    QCommandLineOption opt(QStringLiteral("name"), QStringLiteral("desc"),
+                           QStringLiteral("valueName"), QStringLiteral("default"));
+    QCOMPARE(opt.defaultValues(), QStringList(QStringLiteral("default")));
+    opt.setDefaultValue(QStringLiteral(""));
+    QCOMPARE(opt.defaultValues(), QStringList());
+    opt.setDefaultValue(QStringLiteral("default"));
+    QCOMPARE(opt.defaultValues(), QStringList(QStringLiteral("default")));
+}
+
 void tst_QCommandLineParser::testProcessNotCalled()
 {
     QCoreApplication app(empty_argc, empty_argv);