Refactor a bit.

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"
-
-        "github.com/luci/luci-go/common/clock/testclock"
-        . "github.com/smartystreets/goconvey/convey"
-        "golang.org/x/net/context"
-)
-
-func TestMathRand(t *testing.T) {
-        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)
-                })
-        })
-}