Use int64 to store time.Time internally in memory implementation.

impl/memory/datastore_test.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 (
         "fmt"
         "testing"
+        "time"
 
         dsS "github.com/luci/gae/service/datastore"
         "github.com/luci/gae/service/datastore/dskey"
         "github.com/luci/gae/service/datastore/serialize"
         infoS "github.com/luci/gae/service/info"
         . "github.com/smartystreets/goconvey/convey"
         "golang.org/x/net/context"
 )
 
 func TestDatastoreKinder(t *testing.T) {
@@ skipping 503 matching lines @@
 
                 idx.SortBy = append(idx.SortBy, dsS.IndexColumn{Property: "Field1"})
                 So(head.GetCollection(idxKey(idx)), ShouldBeNil)
 
                 t.AddIndexes(&idx)
                 coll = head.GetCollection(idxKey(idx))
                 So(coll, ShouldNotBeNil)
                 So(numItms(coll), ShouldEqual, 4)
         })
 }
+
+// High level test for regression in how zero time is stored,
+// see https://codereview.chromium.org/1334043003/
+func TestDefaultTimeField(t *testing.T) {
+        t.Parallel()
+
+        Convey("Default time.Time{} can be stored", t, func() {
+                type Model struct {
+                        ID   int64 `gae:"$id"`
+                        Time time.Time
+                }
+                ds := dsS.Get(Use(context.Background()))
+                m := Model{ID: 1}
+                So(ds.Put(&m), ShouldBeNil)
+
+                // Reset to something non zero to ensure zero is fetched.
+                m.Time = time.Now().UTC()
+                So(ds.Get(&m), ShouldBeNil)
+                So(m.Time.IsZero(), ShouldBeTrue)
+        })
+}