Add a NewDatastore helper function.

impl/memory/datastore.go

Index: impl/memory/datastore.go
diff --git a/impl/memory/datastore.go b/impl/memory/datastore.go
index 5b8581a71c8d9e6c3623086b949c3b7b613784dd..efc61d3ba5f1a13ee1ac6bc8c89a04c206a508c9 100644
--- a/impl/memory/datastore.go
+++ b/impl/memory/datastore.go
@@ -11,6 +11,7 @@ import (
 	"golang.org/x/net/context"
 
 	ds "github.com/luci/gae/service/datastore"
+	"github.com/luci/gae/service/info"
 )
 
 //////////////////////////////////// public ////////////////////////////////////
@@ -29,6 +30,29 @@ func useRDS(c context.Context) context.Context {
 	})
 }
 
+// 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.