Fancy Logger

Fancy logger used by AdonisJS CLI apps

Fancy logger for logging colorful messages with consistent UI output. AdonisJs has various command line utilities including ace. (A framework to create CLI applications). We make use of this module to make sure that all parts of the framework output logs with consistent formatting.

A big thanks to the creator of signale for being an inspiration for this module.

We didn't used signale coz of following reasons:

1. AdonisJs uses kleur for colorizing strings and signale uses chalk. We want to avoid loading different color libraries.
2. Signale has too many features that we don't need.

Table of contents

• Installation
• Usage
• Using a custom instance
• Deferred logs
• Testing log messages

Installation

Install the package from npm registry as follows:

npm i @poppinss/fancy-logs

# yarn
yarn add @poppinss/fancy-logs

Usage

Import and use the logger as follows

import fancyLogger from '@poppinss/fancy-logs'

fancyLogger.success('Operation successful')
fancyLogger.info('Hello from L59')
fancyLogger.pending('Write release notes for %s', '1.2.0')
fancyLogger.fatal(new Error('Unable to acquire lock'))
fancyLogger.watch('Recursively watching build directory...')
fancyLogger.complete({
  prefix: '[task]',
  message: 'Fix issue #59',
})

Using a custom instance

import { Logger } from '@poppinss/fancy-logs'

/**
 * Disable underlines and icons
 */
const fancyLogger = new Logger({
  underline: false,
  icon: false,
  color: true,
})

Deferred logs

When running CLI tasks from 3rd party plugins, you may end in a situation where multiple plugins will print the same log messages. For example:

Plugin A updates tsconfig.json

logger.update('tsconfig.json')

Plugin B update tsconfig.json with a different option but logs the same message

logger.update('tsconfig.json')

After this the CLI will reflect 2 lines saying update tsconfig.json. You can avoid this behavior by pausing and resuming the logger.

logger.pauseLogger()

runPluginA()
runPluginB()

const logsSet = new Set()
logger.resumeLogger((message) => {
  if (logsSet.has(message.message)) {
    return false
  }

  logsSet.add(message.message)
  return true
})

The callback passed to resumeLogger must return true when it wants to print a message and false for opposite behavior.

Testing log messages

You can also safely test the log messages by creating an instance with fake=true. For example:

import { Logger } from '@poppinss/fancy-logs'

const logger = new Logger({ fake: true })

logger.warn('Fire in the hole')
logger.info('Account created')

assert.deepEqual(logger.logs, [
  'underline(yellow(warn)) Fire in the hole',
  'underline(blue(info)) Account created',
])