+
+ d.D = Duration(time.Second)
+ err = json.Unmarshal([]byte(`{"D":"0"}`), &d)
+ c.Check(err, check.IsNil)
+ c.Check(d.D.Duration(), check.Equals, time.Duration(0))
+
+ d.D = Duration(time.Second)
+ err = json.Unmarshal([]byte(`{"D":0}`), &d)
+ c.Check(err, check.IsNil)
+ c.Check(d.D.Duration(), check.Equals, time.Duration(0))