Move dummy service implementations into their own package.

go/src/infra/gae/libs/gae/mathrand_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 gae
+
+import (
+        "math/rand"
+        "testing"
+        "time"
+
+        "golang.org/x/net/context"
+
+        "github.com/luci/luci-go/common/clock/testclock"
+
+        . "github.com/smartystreets/goconvey/convey"
+)
+
+func TestMathRand(t *testing.T) {

[estaab, 2015/07/13 18:26:35]

I'm a little confused by this being here. This is just a test for the standard
math/rand module?

[iannucci, 2015/07/14 01:35:53]

gae (for better or worse.. actually probably just worse), has a "MathRand"
service (like RawDatastore and the rest), and this is a test for that. It should
be moved to a different, separate package like
https://github.com/luci/luci-go/tree/master/common/clock . I've added a TODO.

+        t.Parallel()
+
+        Convey("test mathrand", t, func() {
+                now := time.Date(2015, 1, 1, 0, 0, 0, 0, time.UTC)
+                c, _ := testclock.UseTime(context.Background(), now)
+
+                // Note that the non-randomness below is because time is fixed at the
+                // top of the outer test function. Normally it would evolve with time.
+                Convey("unset", func() {
+                        r := rand.New(rand.NewSource(now.UnixNano()))
+                        i := r.Int()
+                        So(GetMathRand(c).Int(), ShouldEqual, i)
+                        So(GetMathRand(c).Int(), ShouldEqual, i)
+                })
+
+                Convey("set persistance", func() {
+                        c = SetMathRand(c, rand.New(rand.NewSource(now.UnixNano())))
+                        r := rand.New(rand.NewSource(now.UnixNano()))
+                        So(GetMathRand(c).Int(), ShouldEqual, r.Int())
+                        So(GetMathRand(c).Int(), ShouldEqual, r.Int())
+                })
+
+                Convey("nil set", func() {
+                        c = SetMathRand(c, nil)
+                        r := rand.New(rand.NewSource(now.UnixNano()))
+                        i := r.Int()
+                        So(GetMathRand(c).Int(), ShouldEqual, i)
+                        So(GetMathRand(c).Int(), ShouldEqual, i)
+                })
+        })
+}