public void TestDate1() { JObject json = new JObject { { "message", "2014-01-31 08:23:47,123" } }; string grokJson = @"{ ""TimberWinR"":{ ""Filters"":[ { ""date"":{ ""match"":[ ""message"", ""yyyy-MM-dd HH:mm:ss,fff"" ] } }] } }"; Configuration c = Configuration.FromString(grokJson); DateFilter date = c.Filters.First() as DateFilter; Assert.IsTrue(date.Apply(json)); var ts = json["@timestamp"].ToString(); Assert.AreEqual(ts, "1/31/2014 8:23:47 AM"); }