Add context-aware "time" library wrapper.

go/src/infra/libs/clock/systemtimer_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 clock
+
+import (
+        "testing"
+        "time"
+
+        . "github.com/smartystreets/goconvey/convey"
+)
+
+func TestSystemTimer(t *testing.T) {
+        t.Parallel()
+
+        Convey(`A systemTimer instance`, t, func() {
+                t := new(systemTimer)
+
+                Convey(`Should start with a nil channel.`, func() {
+                        So(t.GetC(), ShouldBeNil)
+                })
+
+                Convey(`When stopped, should return inactive.`, func() {
+                        So(t.Stop(), ShouldBeFalse)
+                })
+
+                Convey(`When reset`, func() {
+                        active := t.Reset(1 * time.Hour)
+                        So(active, ShouldBeFalse)
+
+                        Convey(`When reset to a short duration`, func() {
+                                active := t.Reset(1 * time.Microsecond)
+
+                                Convey(`Should return active.`, func() {
+                                        So(active, ShouldBeTrue)
+                                })
+
+                                Convey(`Should trigger shortly.`, func() {
+                                        tm := <-t.GetC()
+                                        So(tm, ShouldNotResemble, time.Time{})
+                                })
+                        })
+
+                        Convey(`When stopped, should return active and have a non-nil C.`, func() {
+                                active := t.Stop()
+                                So(active, ShouldBeTrue)
+                                So(t.GetC(), ShouldNotBeNil)
+                        })
+
+                        Convey(`When stopped, should return active.`, func() {
+                                active := t.Stop()
+                                So(active, ShouldBeTrue)
+                        })
+
+                        Convey(`Should have a non-nil channel.`, func() {
+                                So(t.GetC(), ShouldNotBeNil)
+                        })
+
+                        Reset(func() {
+                                t.Stop()
+                        })
+                })
+        })
+}