Better attempt at an appengine wrapper.

go/src/infra/gae/libs/wrapper/dummy_test.go

Index: go/src/infra/gae/libs/wrapper/dummy_test.go
diff --git a/go/src/infra/gae/libs/wrapper/dummy_test.go b/go/src/infra/gae/libs/wrapper/dummy_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..f67a08e417663e6b88baa3301a8b10fcba2d9dbc
--- /dev/null
+++ b/go/src/infra/gae/libs/wrapper/dummy_test.go
@@ -0,0 +1,88 @@
+// 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 wrapper
+
+import (
+	"math/rand"
+	"testing"
+	"time"
+
+	"golang.org/x/net/context"
+
+	"appengine/memcache"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestContextAccess(t *testing.T) {
+	Convey("Context Access", t, func() {
+		c := context.Background()
+
+		Convey("blank", func() {
+			So(GetDS(c), ShouldBeNil)
+			So(GetMC(c), ShouldBeNil)
+			So(GetTQ(c), ShouldBeNil)
+			So(GetGI(c), ShouldBeNil)
+
+			now := time.Now()
+			So(GetTimeNow(c), ShouldHappenAfter, now)

[M-A Ruel, 2015/05/25 17:14:51]

FYI, that fails on Windows and likely on oversubscribed VMs.

[iannucci, 2015/05/26 18:25:06]

yeah I was wondering.... should I sleep for a second or something? I hate
sleeping in tests :(

[M-A Ruel, 2015/05/27 00:27:10]

Use >=, this will catch 99.9999% of the cases except when the clock goes
backward but it's infrequent enough it's not worth optimizing for.

+		})
+
+		Convey("DS", func() {
+			c = SetDS(c, DummyDS())
+			So(GetDS(c), ShouldNotBeNil)
+			So(func() { GetDS(c).Kind(nil) }, ShouldPanic)
+		})
+
+		Convey("MC", func() {
+			c = SetMC(c, DummyMC())
+			So(GetMC(c), ShouldNotBeNil)
+			So(func() { GetMC(c).InflateCodec(memcache.Codec{}) }, ShouldPanic)
+		})
+
+		Convey("TQ", func() {
+			c = SetTQ(c, DummyTQ())
+			So(GetTQ(c), ShouldNotBeNil)
+			So(func() { GetTQ(c).Purge("") }, ShouldPanic)
+		})
+
+		Convey("GI", func() {
+			c = SetGI(c, DummyGI())
+			So(GetGI(c), ShouldNotBeNil)
+			So(func() { GetGI(c).Datacenter() }, ShouldPanic)
+		})
+
+		Convey("QY", func() {
+			q := DummyQY()
+			So(func() { q.Distinct() }, ShouldPanic)
+		})
+
+		Convey("TimeNow", func() {
+			thing := time.Date(2000, time.August, 20, 0, 0, 0, 0, time.UTC)
+			c = SetTimeNow(c, &thing)
+			So(GetTimeNow(c), ShouldResemble, thing)
+
+			Convey("MathRand", func() {
+				r := rand.New(rand.NewSource(thing.UnixNano()))
+				i := r.Int()
+
+				// when it's unset it picks TimeNow every time
+				So(GetMathRand(c).Int(), ShouldEqual, i)
+				So(GetMathRand(c).Int(), ShouldEqual, i)
+
+				// But we could set it to something concrete to have it persist.
+				c = SetMathRand(c, rand.New(rand.NewSource(thing.UnixNano())))
+				r = rand.New(rand.NewSource(thing.UnixNano()))
+				So(GetMathRand(c).Int(), ShouldEqual, r.Int())
+				So(GetMathRand(c).Int(), ShouldEqual, r.Int())
+			})
+
+			c = SetTimeNow(c, nil)
+			now := time.Now()
+			So(GetTimeNow(c), ShouldHappenAfter, now)
+		})
+
+	})
+}