Log Module

Logging module based on Zerolog.

• Installation
• Documentation
  • Usage
  • Context
  • Testing

Installation

go get github.com/ankorstore/yokai/log

Documentation

This module provides a Logger, offering all Zerolog methods.

Usage

To create a Logger:

package main

import (
	"os"

	"github.com/ankorstore/yokai/log"
	"github.com/rs/zerolog"
)

var logger, _ = log.NewDefaultLoggerFactory().Create()

// equivalent to:
var logger, _ = log.NewDefaultLoggerFactory().Create(
	log.WithServiceName("default"),   // adds {"service":"default"} to log records
	log.WithLevel(zerolog.InfoLevel), // logs records with level >= info
	log.WithOutputWriter(os.Stdout),  // sends logs records to stdout
)

To use the Logger:

package main

import (
	"github.com/ankorstore/yokai/log"
)

func main() {
	logger, _ := log.NewDefaultLoggerFactory().Create()

	logger.Info().Msg("some message") // {"level:"info", "service":"default", "message":"some message"}
}

See Zerolog documentation for more details about available methods.

Context

This module provides the log.CtxLogger() function that allow to extract the logger from a context.Context.

If no logger is found in context, a default Zerolog based logger will be used.

Testing

This module provides a TestLogBuffer, recording log records to be able to assert on them after logging:

package main

import (
	"fmt"

	"github.com/ankorstore/yokai/log"
	"github.com/ankorstore/yokai/log/logtest"
)

func main() {
	buffer := logtest.NewDefaultTestLogBuffer()

	logger, _ := log.NewDefaultLoggerFactory().Create(log.WithOutputWriter(buffer))

	logger.Info().Msg("some message example")

	// test on attributes exact matching
	hasRecord, _ := buffer.HasRecord(map[string]interface{}{
		"level":   "info",
		"message": "some message example",
	})

	fmt.Printf("has record: %v", hasRecord) // has record: true

	// test on attributes partial matching
	containRecord, _ := buffer.ContainRecord(map[string]interface{}{
		"level":   "info",
		"message": "message",
	})

	fmt.Printf("contain record: %v", containRecord) // contain record: true
}

You can also use the provided test assertion helpers in your tests:

• AssertHasLogRecord: to assert on exact attributes match
• AssertHasNotLogRecord: to assert on exact attributes non match
• AssertContainLogRecord: to assert on partial attributes match
• AssertContainNotLogRecord: to assert on partial attributes non match

and use Dump() to print the current content of the TestLogBuffer.

For example:

package main_test

import (
	"fmt"
	"testing"

	"github.com/ankorstore/yokai/log"
	"github.com/ankorstore/yokai/log/logtest"
)

func TestLogger(t *testing.T) {
	buffer := logtest.NewDefaultTestLogBuffer()
	
	logger, _ := log.NewDefaultLoggerFactory().Create(log.WithOutputWriter(buffer))

	logger.Info().Msg("some message example")

	// print records
	buffer.Dump()
	
	// assertion success
	logtest.AssertHasLogRecord(t, buffer, map[string]interface{}{
		"level":   "info",
		"message": "some message example",
	})

	// assertion success
	logtest.AssertHasNotLogRecord(t, buffer, map[string]interface{}{
		"level":   "info",
		"message": "some invalid example",
	})

	// assertion success
	logtest.AssertContainLogRecord(t, buffer, map[string]interface{}{
		"level":   "info",
		"message": "message",
	})

	// assertion success
	logtest.AssertContainNotLogRecord(t, buffer, map[string]interface{}{
		"level":   "info",
		"message": "invalid",
	})
}