diff --git a/addons/tabswitcher/autotests/tabswitchertest.h b/addons/tabswitcher/autotests/tabswitchertest.h
--- a/addons/tabswitcher/autotests/tabswitchertest.h
+++ b/addons/tabswitcher/autotests/tabswitchertest.h
@@ -32,5 +32,6 @@
 
 private Q_SLOTS:
     void testLongestCommonPrefix();
+    void testLongestCommonPrefix_data();
 };
 
diff --git a/addons/tabswitcher/autotests/tabswitchertest.cpp b/addons/tabswitcher/autotests/tabswitchertest.cpp
--- a/addons/tabswitcher/autotests/tabswitchertest.cpp
+++ b/addons/tabswitcher/autotests/tabswitchertest.cpp
@@ -35,30 +35,43 @@
 
 void KateTabSwitcherTest::testLongestCommonPrefix()
 {
-    // standard case
+    QFETCH(std::vector<QString>, input_strings);
+    QFETCH(QString, expected);
+
+    QCOMPARE(detail::longestCommonPrefix(input_strings), expected);
+}
+
+void KateTabSwitcherTest::testLongestCommonPrefix_data()
+{
+    QTest::addColumn<std::vector<QString>>("input_strings");
+    QTest::addColumn<QString>("expected");
     std::vector<QString> strs;
+
+    strs.clear();
     strs.push_back(QLatin1String("/home/user1/a"));
     strs.push_back(QLatin1String("/home/user1/bc"));
-    QCOMPARE(detail::longestCommonPrefix(strs), QLatin1String("/home/user1/"));
+    QTest::newRow("standard case") << strs << QString(QLatin1String("/home/user1/"));
 
-    // empty string at the end of the list
     strs.clear();
     strs.push_back(QLatin1String("/home/a"));
     strs.push_back(QLatin1String("/home/b"));
     strs.push_back(QLatin1String(""));
-    QCOMPARE(detail::longestCommonPrefix(strs), QLatin1String(""));
+    QTest::newRow("empty string at the end of the list") << strs << QString();
 
-    // empty string not only at the end of the list
     strs.clear();
     strs.push_back(QLatin1String(""));
     strs.push_back(QLatin1String("/home/a"));
     strs.push_back(QLatin1String("/home/b"));
     strs.push_back(QLatin1String(""));
-    QCOMPARE(detail::longestCommonPrefix(strs), QLatin1String(""));
+    QTest::newRow("empty string not only at the end of the list") << strs << QString();
 
-    // a prefix with length 1
     strs.clear();
     strs.push_back(QLatin1String("/home/a"));
     strs.push_back(QLatin1String("/etc/b"));
-    QCOMPARE(detail::longestCommonPrefix(strs), QLatin1String("/"));
+    QTest::newRow("a prefix with length 1") << strs << QString(QLatin1String("/"));
+
+    strs.clear();
+    strs.push_back(QLatin1String("a"));
+    strs.push_back(QLatin1String("a"));
+    QTest::newRow("two equal strings") << strs << QString(QLatin1String("a"));
 }
diff --git a/addons/tabswitcher/tabswitcherfilesmodel.h b/addons/tabswitcher/tabswitcherfilesmodel.h
--- a/addons/tabswitcher/tabswitcherfilesmodel.h
+++ b/addons/tabswitcher/tabswitcherfilesmodel.h
@@ -80,6 +80,6 @@
     FilenameList data_;
 };
 
-QString longestCommonPrefix(std::vector<QString>& strs);
+QString longestCommonPrefix(std::vector<QString> const & strs);
 
 }
diff --git a/addons/tabswitcher/tabswitcherfilesmodel.cpp b/addons/tabswitcher/tabswitcherfilesmodel.cpp
--- a/addons/tabswitcher/tabswitcherfilesmodel.cpp
+++ b/addons/tabswitcher/tabswitcherfilesmodel.cpp
@@ -30,7 +30,7 @@
      * see also http://www.cplusplus.com/forum/beginner/83540/
      * Note that if strs contains the empty string, the result will be ""
      */
-    QString longestCommonPrefix(std::vector<QString>& strs) {
+    QString longestCommonPrefix(std::vector<QString> const & strs) {
         int n = INT_MAX;
         if (strs.size() <= 0) {
             return QString();