GUI correspondence tests: better err msg, but still broken

Tests/Unit/GUI/TestGUICoreObjectCorrespondence.cpp

@@ -9,7 +9,7 @@ class TestGUICoreObjectCorrespondence : public ::testing::Test {
 public:
     void GUICoreObjectCorrespondence(const SessionItem& gui_object, const INode& core_object)
     {
-        EXPECT_EQ(gui_object.displayName(), QString::fromStdString(core_object.className()));
+        EXPECT_EQ(gui_object.displayName().toStdString(), core_object.className());
     }
 };