Make obtaining the Testable interface actually part of the interface.

impl/memory/taskqueue.go

 // Copyright 2015 The Chromium 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 memory
 
 import (
         "regexp"
         "sync/atomic"
 
@@ skipping 127 matching lines @@
                                         s.OldestETA = t.ETA
                                 }
                         }
                         cb(&s, nil)
                 }
         }
 
         return nil
 }
 
+func (t *taskqueueImpl) Testable() tq.Testable {
+        return t
+}
+
 /////////////////////////////// taskqueueTxnImpl ///////////////////////////////
 
 type taskqueueTxnImpl struct {
         *txnTaskQueueData
 
         ctx context.Context
         ns  string
 }
 
 var _ interface {
@@ skipping 57 matching lines @@
 }
 
 func (t *taskqueueTxnImpl) Purge(string) error {
         return errors.New("taskqueue: cannot Purge from a transaction")
 }
 
 func (t *taskqueueTxnImpl) Stats([]string, tq.RawStatsCB) error {
         return errors.New("taskqueue: cannot Stats from a transaction")
 }
 
+func (t *taskqueueTxnImpl) Testable() tq.Testable {
+        return t
+}
+
 ////////////////////////////// private functions ///////////////////////////////
 
 var validTaskName = regexp.MustCompile("^[0-9a-zA-Z\\-\\_]{0,500}$")
 
 const validTaskChars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_"
 
 func mkName(c context.Context, cur string, queue map[string]*tq.Task) string {
         _, ok := queue[cur]
         for !ok && cur == "" {
                 name := [500]byte{}
                 for i := 0; i < 500; i++ {
                         name[i] = validTaskChars[mathrand.Get(c).Intn(len(validTaskChars))]
                 }
                 cur = string(name[:])
                 _, ok = queue[cur]
         }
         return cur
 }
 
 func dupQueue(q tq.QueueData) tq.QueueData {
         r := make(tq.QueueData, len(q))
         for k, q := range q {
                 r[k] = make(map[string]*tq.Task, len(q))
                 for tn, t := range q {
                         r[k][tn] = t.Duplicate()
                 }
         }
         return r
 }