add tests and docs for time location

README.md

@@ -50,7 +50,7 @@ var DefaultLogger = Logger{
 	Writer:     &IOWriter{os.Stderr},
 }
 
-// A Logger represents an active logging object that generates lines of JSON output to an io.Writer.
+// Logger represents an active logging object that generates lines of JSON output to an io.Writer.
 type Logger struct {
 	// Level defines log levels.
 	Level Level
@@ -59,13 +59,16 @@ type Logger struct {
 	// If Caller is negative, adds the full /path/to/file:line of the "caller" key.
 	Caller int
 
-	// TimeField defines the time filed name in output.  It uses "time" in if empty.
+	// TimeField defines the time field name in output.  It uses "time" in if empty.
 	TimeField string
 
-	// TimeFormat specifies the time format in output. It uses RFC3339 with millisecond if empty.
-	// If set with `TimeFormatUnix/TimeFormatUnixMs/TimeFormatUnixWithMs`, timestamps are formated.
+	// TimeFormat specifies the time format in output. Uses RFC3339 with millisecond if empty.
+	// If set to `TimeFormatUnix/TimeFormatUnixMs`, timestamps will be formatted.
 	TimeFormat string
 
+	// TimeLocation specifices that the location of TimeFormat used. Uses time.Local if empty.
+	TimeLocation *time.Location
+
 	// Writer specifies the writer of output. It uses a wrapped os.Stderr Writer in if empty.
 	Writer Writer
 }

logger_test.go

@@ -367,6 +367,29 @@ func TestLoggerTimeFormat(t *testing.T) {
 	logger.Info().Int64("timestamp_ms", timeNow().UnixNano()/1000000).Msg("this is rfc3339 time log entry")
 }
 
+func TestLoggerTimeLocation(t *testing.T) {
+	logger := Logger{}
+
+	for _, format := range []string{"", time.RFC822} {
+		logger.TimeFormat = format
+
+		logger.TimeLocation = nil
+		logger.Info().Msgf("this is TimeFormat=%#v TimeLocation=nil log entry", logger.TimeFormat)
+
+		logger.TimeLocation = time.Local
+		logger.Info().Msgf("this is TimeFormat=%#v TimeLocation=time.Local log entry", logger.TimeFormat)
+
+		logger.TimeLocation = time.UTC
+		logger.Info().Msgf("this is TimeFormat=%#v TimeLocation=time.UTC log entry", logger.TimeFormat)
+
+		logger.TimeLocation, _ = time.LoadLocation("Asia/Singapore")
+		logger.Info().Msgf("this is TimeFormat=%#v TimeLocation=Asia/Singapore log entry", logger.TimeFormat)
+
+		logger.TimeLocation, _ = time.LoadLocation("America/New_York")
+		logger.Info().Msgf("this is TimeFormat=%#v TimeLocation=America/New_York log entry", logger.TimeFormat)
+	}
+}
+
 func TestLoggerTimeOffset(t *testing.T) {
 	logger := Logger{}