Add a NewDatastore helper function.

impl/memory/datastore.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 (
         "errors"
         "fmt"
 
         "golang.org/x/net/context"
 
         ds "github.com/luci/gae/service/datastore"
+        "github.com/luci/gae/service/info"
 )
 
 //////////////////////////////////// public ////////////////////////////////////
 
 // useRDS adds a gae.Datastore implementation to context, accessible
 // by gae.GetDS(c)
 func useRDS(c context.Context) context.Context {
         return ds.SetRawFactory(c, func(ic context.Context) ds.RawInterface {
                 dsd := cur(ic).Get(memContextDSIdx)
 
                 ns := curGID(ic).namespace
                 if x, ok := dsd.(*dataStoreData); ok {
                         return &dsImpl{x, ns, ic}
                 }
                 return &txnDsImpl{dsd.(*txnDataStoreData), ns}
         })
 }
 
+// NewDatastore creates a new standalone memory implementation of the datastore,
+// suitable for embedding for doing in-memory data organization.
+//
+// It's configured by default with the following settings:
+//   * AutoIndex(true)
+//   * Consistent(true)
+//   * DisableSpecialEntities(true)
+//
+// These settings can of course be changed by using the Testable() interface.
+func NewDatastore(aid, ns string) (ds.Interface, error) {
+        ctx := UseWithAppID(context.Background(), aid)
+        ctx, err := info.Get(ctx).Namespace(ns)
+        if err != nil {
+                return nil, err
+        }
+        ret := ds.Get(ctx)
+        t := ret.Testable()

[Vadim Sh., 2015/09/29 20:08:36]

name 'Testable' is unfortunate, considering it is used in prod code now

[iannucci, 2015/09/29 20:09:45]

Yeah that occurred to me. AlterSemantics?

[Vadim Sh., 2015/09/29 20:12:03]

"Tweaks"? "Hacks"? :) 

+        t.AutoIndex(true)
+        t.Consistent(true)
+        t.DisableSpecialEntities(true)
+        return ret, nil
+}
+
 //////////////////////////////////// dsImpl ////////////////////////////////////
 
 // dsImpl exists solely to bind the current c to the datastore data.
 type dsImpl struct {
         data *dataStoreData
         ns   string
         c    context.Context
 }
 
 var _ ds.RawInterface = (*dsImpl)(nil)
@@ skipping 139 matching lines @@
         return countQuery(fq, d.data.parent.aid, d.ns, true, d.data.snap, d.data.snap)
 }
 
 func (*txnDsImpl) RunInTransaction(func(c context.Context) error, *ds.TransactionOptions) error {
         return errors.New("datastore: nested transactions are not supported")
 }
 
 func (*txnDsImpl) Testable() ds.Testable {
         return nil
 }