pino-test

Provides a set of utilities for verifying logs generated by the Pino logger.

Getting started

npm install pino-test --save-dev

const test = require('node:test')
const pino = require('pino')
const pinoTest = require('pino-test')

test('pino should log a info message', async () => {
  const stream = pinoTest.sink()
  const logger = pino(stream)

  logger.info('hello world')

  const expected = { msg: 'hello world', level: 30 }
  await pinoTest.once(stream, expected)
})

// with a own assert function
function is (received, expected, msg) {
  if (received.msg !== expected.msg) {
    throw new Error(`expected msg ${expected.msg} doesn't match the received one ${received.msg}`)
  }
}

test('pino should log a info message using a own assert function', async () => {
  const stream = pinoTest.sink()
  const logger = pino(stream)

  logger.info('hello world')

  const expected = { msg: 'hello world', level: 30 }
  await pinoTest.once(stream, expected, is)
})

API

• sink()
• once()
• consecutive()

pinoTest.sink({ destroyOnError = false, emitErrorEvent = false }) => Transform

Create a Pino destination stream to easily inspect the logs processed by Pino.

const pino = require('pino')
const pinoTest = require('pino-test')

const stream = pinoTest.sink()
const logger = pino(stream)

logger.info('hello world')

stream.once('data', (data) => {
  console.log(chunk.msg) // 'hello world'
  console.log(chunk.level) // 30
})

Destroy the stream on error

const pino = require('pino')
const pinoTest = require('pino-test')

const stream = pinoTest.sink({ destroyOnError: true })
stream.write('helloworld')
stream.end()

stream.once('close', () => {
  console.log('close event') // "close event"
})

Destroy and send error event on error

const pino = require('pino')
const pinoTest = require('pino-test')

const stream = pinoTest.sink({ destroyOnError = false, emitErrorEvent = false })
stream.write('helloworld')
stream.end()

stream.on('error', (err) => {
  console.log(err) // Unexpected token h in JSON at position 0
})

stream.on('close', () => {
  console.log('close event') // "close event"
})

Send error event on error

const pino = require('pino')
const pinoTest = require('pino-test')

const stream = pinoTest.sink({ emitErrorEvent = false })
stream.write('helloworld')
stream.end()

stream.on('error', (err) => {
  console.log(err) // Unexpected token h in JSON at position 0
})

once(stream, expected, is) => Promise<void>

Assert that a single log is expected. The function internally

• assert log message time is less than or equal to the current time
• assert log message pid matches the current process id
• assert log message hostname matches the current hostname
• uses the default deepStrictEqual assert function of the node:assert module.

const pino = require('pino')
const pinoTest = require('pino-test')

const stream = pinoTest.sink()
const logger = pino(stream)

logger.info('hello world')

const expected = { msg: 'hello world', level: 30 }
await pinoTest.once(stream, expected) // doesn't throw a diff error
await pinoTest.once(stream, { msg: 'bye world', level: 30 }) // throw a diff error

// OR logging an object
logger.info({ hello: 'world', hi: 'world' })
await pinoTest.once(stream, { hello: 'world', hi: 'world', level: 30 }) // doesn't throw a diff error
await pinoTest.once(stream, { hello: 'world', level: 30 }) // throw a diff error

// OR using a custom assert function
function is (received, expected, msg) {
  if (received.msg !== expected.msg) {
    throw new Error(`expected msg ${expected.msg} doesn't match the received one ${received.msg}`)
  }
}

await pinoTest.once(stream, expected, is) // doesn't throw an error
await pinoTest.once(stream, { msg: 'bye world', level: 30 }, is) // throw an error

consecutive(stream, expected, is) => Promise<void>

Assert that consecutive logs are expected. The function internally

• assert log message time is less than or equal to the current time
• assert log message pid matches the current process id
• assert log message hostname matches the current hostname
• uses the default deepStrictEqual assert function of the node:assert module.

const pino = require('pino')
const pinoTest = require('pino-test')

const stream = pinoTest.sink()
const logger = pino(stream)

logger.info('hello world')
logger.info('hi world')

const expected = [
  { msg: 'hello world', level: 30 },
  { msg: 'hi world', level: 30 }
]

await pinoTest.consecutive(stream, expected) // doesn't throw a diff error
await pinoTest.consecutive(stream, [{ msg: 'bye world', level: 30 }]) // throw a diff error

// OR logging an object
logger.info({ hello: 'world' })
logger.info({ hi: 'world' })
await pinoTest.consecutive(stream, [
  { hello: 'world', level: 30 },
  { hi: 'world', level: 30 }
])

// OR using a custom assert function
function is (received, expected, msg) {
  if (received.msg !== expected.msg) {
    throw new Error(`expected msg ${expected.msg} doesn't match the received one ${received.msg}`)
  }
}

await pinoTest.consecutive(stream, expected, is) // doesn't throw an error
await pinoTest.consecutive(stream, [{ msg: 'bye world', level: 30 }], is) // throw an error