Revert "Revert "Move rand string func to util for reuse""

This reverts commit acebe24bf3.

pkg/util/rand/rand_test.go

@@ -0,0 +1,37 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package rand
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestString(t *testing.T) {
+	valid := "0123456789abcdefghijklmnopqrstuvwxyz"
+	for _, l := range []int{0, 1, 2, 10, 123} {
+		s := String(l)
+		if len(s) != l {
+			t.Errorf("expected string of size %d, got %q", l, s)
+		}
+		for _, c := range s {
+			if !strings.ContainsRune(valid, c) {
+				t.Errorf("expected valid charaters, got %v", c)
+			}
+		}
+	}
+}