diff --git a/addons/externaltools/autotests/externaltooltest.cpp b/addons/externaltools/autotests/externaltooltest.cpp
index 36c8296b9..cd1e851a1 100644
--- a/addons/externaltools/autotests/externaltooltest.cpp
+++ b/addons/externaltools/autotests/externaltooltest.cpp
@@ -1,99 +1,114 @@
 /* This file is part of the KDE project
  *
  *  Copyright 2019 Dominik Haumann <dhaumann@kde.org>
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  *  Library General Public License for more details.
  *
  *  You should have received a copy of the GNU Library General Public License
  *  along with this library; see the file COPYING.LIB.  If not, write to
  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  *  Boston, MA 02110-1301, USA.
  */
 
 #include "externaltooltest.h"
 #include "../kateexternaltool.h"
 #include "../katetoolrunner.h"
 
 #include <QtTest>
 #include <QString>
 
 #include <KConfig>
 #include <KConfigGroup>
 
 QTEST_MAIN(ExternalToolTest)
 
 void ExternalToolTest::initTestCase()
 {
 }
 
 void ExternalToolTest::cleanupTestCase()
 {
 }
 
 void ExternalToolTest::testLoadSave()
 {
     KConfig config;
     KConfigGroup cg(&config, "tool");
 
     KateExternalTool tool;
     tool.name = QStringLiteral("git cola");
     tool.icon = QStringLiteral("git-cola");
     tool.executable = QStringLiteral("git-cola");
     tool.arguments = QStringLiteral("none");
     tool.input = QStringLiteral("in");
     tool.workingDir = QStringLiteral("/usr/bin");
     tool.mimetypes = QStringList{ QStringLiteral("everything") };
     tool.hasexec = true;
     tool.actionName = QStringLiteral("asdf");
     tool.cmdname = QStringLiteral("git-cola");
     tool.saveMode = KateExternalTool::SaveMode::None;
 
     tool.save(cg);
 
     KateExternalTool clonedTool;
     clonedTool.load(cg);
     QCOMPARE(tool.name, clonedTool.name);
 }
 
 void ExternalToolTest::testRunListDirectory()
 {
     auto tool = new KateExternalTool();
     tool->name = QStringLiteral("ls");
     tool->icon = QStringLiteral("none");
     tool->executable = QStringLiteral("ls");
     tool->arguments = QStringLiteral("/usr");
     tool->workingDir = QStringLiteral("/tmp");
     tool->mimetypes = QStringList{};
     tool->hasexec = true;
     tool->actionName = QStringLiteral("ls");
     tool->cmdname = QStringLiteral("ls");
     tool->saveMode = KateExternalTool::SaveMode::None;
 
     // 1. /tmp $ ls /usr
     KateToolRunner runner1(tool);
     runner1.run();
     runner1.waitForFinished();
     QVERIFY(runner1.outputData().contains(QStringLiteral("bin")));
 
     // 2. /usr $ ls
     auto tool2 = new KateExternalTool(*tool);
     tool2->arguments.clear();
     tool2->workingDir = QStringLiteral("/usr");
     KateToolRunner runner2(tool2);
     runner2.run();
     runner2.waitForFinished();
     QVERIFY(runner2.outputData().contains(QStringLiteral("bin")));
 
     // 1. and 2. must give the same result
     QCOMPARE(runner1.outputData(), runner2.outputData());
 }
 
+void ExternalToolTest::testRunTac()
+{
+    auto tool = new KateExternalTool();
+    tool->name = QStringLiteral("tac");
+    tool->executable = QStringLiteral("tac");
+    tool->input = QStringLiteral("a\nb\nc\n");
+    tool->saveMode = KateExternalTool::SaveMode::None;
+
+    // run tac to reverse order
+    KateToolRunner runner(tool);
+    runner.run();
+    runner.waitForFinished();
+    QCOMPARE(runner.outputData(), QStringLiteral("c\nb\na\n"));
+}
+
 // kate: space-indent on; indent-width 4; replace-tabs on;
diff --git a/addons/externaltools/autotests/externaltooltest.h b/addons/externaltools/autotests/externaltooltest.h
index 8d4fd69f5..65a1b8f8f 100644
--- a/addons/externaltools/autotests/externaltooltest.h
+++ b/addons/externaltools/autotests/externaltooltest.h
@@ -1,41 +1,42 @@
 /* This file is part of the KDE project
  *
  *  Copyright 2019 Dominik Haumann <dhaumann@kde.org>
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  *  Library General Public License for more details.
  *
  *  You should have received a copy of the GNU Library General Public License
  *  along with this library; see the file COPYING.LIB.  If not, write to
  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  *  Boston, MA 02110-1301, USA.
  */
 
 #ifndef KATE_TOOLRUNNER_TEST_H
 #define KATE_TOOLRUNNER_TEST_H
 
 #include <QObject>
 
 class ExternalToolTest : public QObject
 {
     Q_OBJECT
 
 public Q_SLOTS:
     void initTestCase();
     void cleanupTestCase();
 
 private Q_SLOTS:
     void testLoadSave();
     void testRunListDirectory();
+    void testRunTac();
 };
 
 #endif
 
 // kate: space-indent on; indent-width 4; replace-tabs on;