Interface update, per-method Contexts.

impl/memory/testing_utils_test.go

 // Copyright 2015 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 memory
 
 import (
         "bytes"
         "fmt"
         "strings"
@@ skipping 98 matching lines @@
         }
         return ret
 }
 
 var (
         prop   = ds.MkProperty
         propNI = ds.MkPropertyNI
 )
 
 func key(elems ...interface{}) *ds.Key {
-        return ds.MakeKey("dev~app", "ns", elems...)
+        return ds.KeyContext{"dev~app", "ns"}.MakeKey(elems...)
 }
 
 func die(err error) {
         if err != nil {
                 panic(err)
         }
 }
 
 // cat is a convenience method for concatenating anything with an underlying
 // byte representation into a single []byte.
@@ skipping 44 matching lines @@
         ret := cat(bytethings...)
         for i := range ret {
                 ret[i] ^= 0xFF
         }
         return ret
 }
 
 func sat(bytethings ...interface{}) string {
         return string(cat(bytethings...))
 }