Make obtaining the Testable interface actually part of the interface.

filter/featureBreaker/tq.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 featureBreaker
 
 import (
         "golang.org/x/net/context"
 
         tq "github.com/luci/gae/service/taskqueue"
@@ skipping 16 matching lines @@
 }
 
 func (t *tqState) Purge(queueName string) error {
         return t.run(func() error { return t.tq.Purge(queueName) })
 }
 
 func (t *tqState) Stats(queueNames []string, cb tq.RawStatsCB) error {
         return t.run(func() error { return t.tq.Stats(queueNames, cb) })
 }
 
+func (t *tqState) Testable() tq.Testable {
+        return t.tq.Testable()
+}
+
 // FilterTQ installs a counter TaskQueue filter in the context.
 func FilterTQ(c context.Context, defaultError error) (context.Context, FeatureBreaker) {
         state := newState(defaultError)
         return tq.AddRawFilters(c, func(ic context.Context, tq tq.RawInterface) tq.RawInterface {
                 return &tqState{state, tq}
         }), state
 }