Update TFileMergerTests.cxx

Author: ferdymercury

io/io/test/TFileMergerTests.cxx

@@ -459,7 +459,7 @@ TEST(TFileMerger, ImportBranches)
       EXPECT_EQ(dummy.FindBranch("a")->GetEntries(), 2);
       ASSERT_TRUE(dummy.FindBranch("b"));
       EXPECT_EQ(dummy.FindBranch("b")->GetEntries(), 2);
-      EXPECT_EQ(atree.GetName(),
+      EXPECT_EQ(TString(atree.GetName()),
                 "ztree"); // As a side effect of trees with zero branches being ignored but it's name kept since it's first
                           // in list, the first tree with branches (name) gets ztree's name.
       ASSERT_TRUE(atree.FindBranch("a"));