improve testdata directory retrieving for unit testing cases

debug/gdebug/gdebug_testdata.go

@@ -0,0 +1,17 @@
+// Copyright 2019-2020 gf Author(https://github.com/gogf/gf). All Rights Reserved.
+//
+// This Source Code Form is subject to the terms of the MIT License.
+// If a copy of the MIT was not distributed with this file,
+// You can obtain one at https://github.com/gogf/gf.
+
+package gdebug
+
+import (
+	"path/filepath"
+)
+
+// TestDataPath retrieves and returns the testdata path of current package.
+// It is used for unit testing cases only.
+func TestDataPath() string {
+	return CallerDirectory() + string(filepath.Separator) + "testdata"
+}