Logger package implements logging methods with formatted output and more detailed logging information than provided in the standard logging package of golang. It is possible to specify the level of logging information to be written as output.

setLevel(level LogLevel)

sets the level of logging information written as output.

There are four possible values for argument level of type LogLevel in ascending info order:

1. LEVEL_ERROR: Only Error logs are written to stderr.
2. LEVEL_WARNING: Warnings and errors are written to stderr.
3. LEVEL_INFO: Errors and warnings are written to stderr, infos to stdout.
4. LEVEL_DEBUG: Errors and warnings are written to stderr, infos and debugs to stdout.

To print logging information you can choose one of the following *log.Logger variables chaining to common I/O writers:

Error
Warning
Info
Debug

The following Log flags are set:

log.Ldate: the date in the local time zone
log.Ltime: the time in the local time zone
log.Lshortfile: final file name element and line number
log.Lmsgprefix: move the "prefix" log level tag from the beginning of the line to before the message

logger.SetLevel(logger.LEVEL_WARNING)
suffix := 2
logger.Error.Printf("error %d", suffix)
logger.Warning.Printf("warning  %d", suffix)
logger.Info.Printf("info  %d", suffix)
logger.Debug.Printf("debug  %d", suffix)

has the following output:

2021/10/07 12:18:12 main.go:16: [ERROR]: error 2
2021/10/07 12:18:12 main.go:17: [WARNING]: warning  2

logger.SetLevel(logger.LEVEL_DEBUG)
suffix := 4
logger.Error.Printf("error %d", suffix)
logger.Warning.Printf("warning  %d", suffix)
logger.Info.Printf("info  %d", suffix)
logger.Debug.Printf("debug  %d", suffix)

prints all logging information:

2021/10/07 12:18:12 main.go:32: [ERROR]: error 4
2021/10/07 12:18:12 main.go:33: [WARNING]: warning  4
2021/10/07 12:18:12 main.go:34: [INFO]: info  4
2021/10/07 12:18:12 main.go:35: [DEBUG]: debug  4

To perform the unit tests, you can call from the root folder:

go test

To run the example:

go run example/main.go

Apache License 2.0