testing: add test for issue 5599
Update #5599
R=golang-dev, r, minux.ma
CC=golang-dev
https://golang.org/cl/9738052
diff --git a/src/pkg/testing/export_test.go b/src/pkg/testing/export_test.go
new file mode 100644
index 0000000..3084efd
--- /dev/null
+++ b/src/pkg/testing/export_test.go
@@ -0,0 +1,7 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package testing
+
+var RoundDown10 = roundDown10