gae cloud: Use with Datastore

impl/cloud/context.go

 // Copyright 2016 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package cloud
 
 import (
         "github.com/luci/gae/impl/dummy"
         ds "github.com/luci/gae/service/datastore"
         "github.com/luci/gae/service/mail"
@@ skipping 33 matching lines @@
         // Dummy services that we don't support.
         c = mail.Set(c, dummy.Mail())
         c = module.Set(c, dummy.Module())
         c = taskqueue.SetRaw(c, dummy.TaskQueue())
         c = user.Set(c, dummy.User())
 
         c = useInfo(c)
 
         // datastore service
         if cfg.DS != nil {
-                cds := cloudDatastore{
-                        client: cfg.DS,
-                }
-                c = cds.use(c)
+                c = UseDatastore(c, cfg.DS)
         } else {
                 c = ds.SetRaw(c, dummy.Datastore())
         }
 
         // memcache service
         if cfg.MC != nil {
                 mc := memcacheClient{
                         client: cfg.MC,
                 }
                 c = mc.use(c)
         } else {
                 c = mc.SetRaw(c, dummy.Memcache())
         }
 
         return c
 }
+
+// UseDatastore installs a datastore implementation into the context.
+func UseDatastore(c context.Context, client *datastore.Client) context.Context {
+        cds := cloudDatastore{
+                client: client,
+        }
+        return cds.use(c)
+}