Fix a bug in the etree_test file.
diff --git a/etree_test.go b/etree_test.go
index 92f75a2..6531da1 100644
--- a/etree_test.go
+++ b/etree_test.go
@@ -47,7 +47,7 @@
 </store>
 `
 	if expected != s {
-		t.Error(testFailed)
+		t.Error("etree: serialization incorrect")
 	}
 
 	// Test the structure of the XML