2 files changed, 50 insertions, 3 deletions

diff --git a/tests/auto/qml/debugger/qmlpreviewtool/tst_qmlpreviewtool.cpp b/tests/auto/qml/debugger/qmlpreviewtool/tst_qmlpreviewtool.cpp
index 1de1271fe0..d1a4416b2e 100644
--- a/tests/auto/qml/debugger/qmlpreviewtool/tst_qmlpreviewtool.cpp
+++ b/tests/auto/qml/debugger/qmlpreviewtool/tst_qmlpreviewtool.cpp
@@ -35,6 +35,7 @@ private slots:
     void inputNotReplayedOnHotReload();
     void hotReloadFailure();
     void interactiveCommands();
+    void restartKeepsArguments();
     void saveAndReplayRoundTrip();
     void classicModeReplaysRecordedInput();
 
@@ -584,6 +585,51 @@ void tst_QmlPreviewTool::interactiveCommands()
     QCOMPARE(m_process.exitCode(), 0);
 }
 
+// Restarting the target must launch it with the same arguments as the first
+// time. Before the fix, every (re)start appended another -qmljsdebugger option
+// to the stored arguments, so they piled up with each restart.
+void tst_QmlPreviewTool::restartKeepsArguments()
+{
+    m_tempDir = std::make_unique<QTemporaryDir>();
+    QVERIFY(m_tempDir->isValid());
+
+    const QString qmlFile = m_tempDir->filePath(QLatin1String("test.qml"));
+    QVERIFY(writeFile(qmlFile, makeQmlContent(QLatin1String("RESTART_OK"))));
+
+    startPreview({ QLatin1String("--interactive"), QLatin1String("--verbose"), m_qmlRuntimePath,
+                   qmlFile });
+    QVERIFY2(waitForOutput(QLatin1String("RESTART_OK")),
+             qPrintable(QLatin1String("Initial load failed. Output:\n") + m_output));
+
+    const QLatin1String starting("Starting '");
+    for (int restarts = 1; restarts <= 2; ++restarts) {
+        sendCommand(QLatin1String("restart"));
+
+        // Wait for the restarted target to be up, so that the next restart
+        // doesn't overtake this one.
+        const bool restarted = QTest::qWaitFor([this, &starting, restarts]() {
+            readProcessOutput();
+            if (m_output.count(starting) != restarts + 1)
+                return false;
+            return m_output.indexOf(QLatin1String("RESTART_OK"), m_output.lastIndexOf(starting))
+                    != -1;
+        }, 30000);
+        QVERIFY2(restarted,
+                 qPrintable(QLatin1String("Target was not restarted. Output:\n") + m_output));
+    }
+
+    const QStringList lines = m_output.split(QLatin1Char('\n'));
+    qsizetype launches = 0;
+    for (const QString &line : lines) {
+        if (!line.startsWith(starting))
+            continue;
+        ++launches;
+        QVERIFY2(line.contains(qmlFile), qPrintable(line));
+        QCOMPARE(line.count(QLatin1String("-qmljsdebugger=")), 1);
+    }
+    QCOMPARE(launches, 3);
+}
+
 // End-to-end round trip: record the input event stream of one session to a .qtd
 // file, then load it in the next session and replay it to restore the UI state.
 void tst_QmlPreviewTool::saveAndReplayRoundTrip()
diff --git a/tools/qmlpreview/qmlpreviewapplication.cpp b/tools/qmlpreview/qmlpreviewapplication.cpp
index de21066a9e..6e327dc589 100644
--- a/tools/qmlpreview/qmlpreviewapplication.cpp
+++ b/tools/qmlpreview/qmlpreviewapplication.cpp
@@ -401,10 +401,11 @@ void QmlPreviewApplication::startProcess()
             this, &QmlPreviewApplication::processHasOutput);
     connect(m_process.data(), QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished),
             this, [this](int){ processFinished(); });
-    m_arguments.append(makeQmlPreviewArgument(m_socketFile));
+    QStringList arguments = m_arguments;
+    arguments.append(makeQmlPreviewArgument(m_socketFile));
     logStatus(QString("Starting '%1 %2' ...")
-                      .arg(m_executablePath, m_arguments.join(QLatin1Char(' '))));
-    m_process->start(m_executablePath, m_arguments);
+                      .arg(m_executablePath, arguments.join(QLatin1Char(' '))));
+    m_process->start(m_executablePath, arguments);
     if (!m_process->waitForStarted()) {
         logError(QString("Could not run '%1': %2").arg(m_executablePath, m_process->errorString()));
         exit(1);