Add context-aware "time" library wrapper.

go/src/infra/libs/clock/testclock/testclock_test.go

Index: go/src/infra/libs/clock/testclock/testclock_test.go
diff --git a/go/src/infra/libs/clock/testclock/testclock_test.go b/go/src/infra/libs/clock/testclock/testclock_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..5fae355ada75b62c39d68a25f20e7eae54800470
--- /dev/null
+++ b/go/src/infra/libs/clock/testclock/testclock_test.go
@@ -0,0 +1,57 @@
+// 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 testclock
+
+import (
+	"testing"
+	"time"
+
+	. "github.com/smartystreets/goconvey/convey"
+	"infra/libs/clock"
+)
+
+func TestTestClock(t *testing.T) {
+	t.Parallel()
+
+	Convey(`A testing clock instance`, t, func() {
+		now := time.Date(2015, 01, 01, 00, 00, 00, 00, time.UTC)
+		c := New(now)
+
+		Convey(`Returns the current time.`, func() {
+			So(c.Now(), ShouldResemble, now)
+		})
+
+		Convey(`When sleeping with a time of zero, immediately awakens.`, func() {
+			c.Sleep(0)
+			So(c.Now(), ShouldResemble, now)
+		})
+
+		Convey(`When sleeping for a period of time, awakens when signalled.`, func() {
+			sleepingC := make(chan struct{})
+			c.SetTimerCallback(func(_ clock.Timer) {
+				close(sleepingC)
+			})
+
+			awakeC := make(chan time.Time)
+			go func() {
+				c.Sleep(2 * time.Second)
+				awakeC <- c.Now()
+			}()
+
+			<-sleepingC
+			c.Set(now.Add(1 * time.Second))
+			c.Set(now.Add(2 * time.Second))
+			So(<-awakeC, ShouldResemble, now.Add(2*time.Second))
+		})
+
+		Convey(`Awakens after a period of time.`, func() {
+			afterC := c.After(2 * time.Second)
+
+			c.Set(now.Add(1 * time.Second))
+			c.Set(now.Add(2 * time.Second))
+			So(<-afterC, ShouldResemble, now.Add(2*time.Second))
+		})
+	})
+}