Unit tests: Print a warning at the end if not all tests passed

It's easy to overlook that Creator returned with a non-zero exit code,
particularly if the last test succeeded.

Change-Id: I6975014aec36c7a267dc88cde41f830d314c90af
Reviewed-by: André Hartmann <aha_1980@gmx.de>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/coreplugin/icore.cpp

@@ -33,9 +33,10 @@
 
 #include <utils/qtcassert.h>
 
-#include <QSysInfo>
 #include <QApplication>
+#include <QDebug>
 #include <QStandardPaths>
+#include <QSysInfo>
 
 /*!
     \namespace Core
@@ -332,6 +333,8 @@ ICore::ICore(MainWindow *mainwindow)
             this, &ICore::saveSettings);
     connect(PluginManager::instance(), &PluginManager::testsFinished, [this] (int failedTests) {
         emit coreAboutToClose();
+        if (failedTests != 0)
+            qWarning("Test run was not successful: %d test(s) failed.", failedTests);
         QCoreApplication::exit(failedTests);
     });
 }