Add context-aware "time" library wrapper.

go/src/infra/libs/clock/clockflag/time_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 clockflag
+
+import (
+        "encoding/json"
+        "flag"
+        "testing"
+        "time"
+
+        . "github.com/smartystreets/goconvey/convey"
+)
+
+func TestTime(t *testing.T) {
+        t.Parallel()
+
+        Convey(`A Time flag`, t, func() {
+                fs := flag.NewFlagSet("test", flag.ContinueOnError)
+                var d Time
+                fs.Var(&d, "time", "Test time parameter.")
+
+                Convey(`Parses a 10-second Time from "2015-05-05T23:47:17+00:00".`, func() {
+                        err := fs.Parse([]string{"-time", "2015-05-05T23:47:17+00:00"})
+                        So(err, ShouldBeNil)
+                        So(d.Time().Equal(time.Unix(1430869637, 0)), ShouldBeTrue)
+                })
+
+                Convey(`Returns an error when parsing "asdf".`, func() {
+                        err := fs.Parse([]string{"-time", "asdf"})
+                        So(err, ShouldNotBeNil)
+                })
+
+                Convey(`When treated as a JSON field`, func() {
+                        var s struct {
+                                T Time `json:"time"`
+                        }
+
+                        testJSON := `{"time":"asdf"}`
+                        Convey(`Fails to unmarshal from `+testJSON+`.`, func() {
+                                testJSON := testJSON
+                                err := json.Unmarshal([]byte(testJSON), &s)
+                                So(err, ShouldNotBeNil)
+                        })
+
+                        Convey(`Marshals correctly to RFC3339 time string.`, func() {
+                                s.T = Time(time.Unix(1430869637, 0))
+                                testJSON, err := json.Marshal(&s)
+                                So(err, ShouldBeNil)
+                                So(string(testJSON), ShouldEqual, `{"time":"2015-05-05T23:47:17Z"}`)
+
+                                Convey(`And Unmarshals correctly.`, func() {
+                                        s.T = Time{}
+                                        err := json.Unmarshal([]byte(testJSON), &s)
+                                        So(err, ShouldBeNil)
+                                        So(s.T.Time().Equal(time.Unix(1430869637, 0)), ShouldBeTrue)
+                                })
+                        })
+                })
+        })
+}