fix: flush thread-stream missing callback

file.js

@@ -1,7 +1,7 @@
 'use strict'
 
 const { Transform, pipeline } = require('stream')
-const pino = require('../pino')
+const pino = require('./pino')
 const { once } = require('events')
 
 module.exports = async function (opts = {}) {

lib/proto.js

@@ -190,7 +190,9 @@ function write (_obj, msg, num) {
   stream.write(s)
 }
 
+function noop () {}
+
 function flush () {
   const stream = this[streamSym]
-  if ('flush' in stream) stream.flush()
+  if ('flush' in stream) stream.flush(noop)
 }

test/fixtures/console-transport.js

@@ -0,0 +1,12 @@
+const { Writable } = require('stream')
+
+module.exports = (options) => {
+  const myTransportStream = new Writable({
+    write (chunk, enc, cb) {
+      // apply a transform and send to stdout
+      console.log(chunk.toString().toUpperCase())
+      cb()
+    }
+  })
+  return myTransportStream
+}

test/syncfalse.test.js

@@ -116,3 +116,13 @@ test('flush does nothing with sync true (default)', async () => {
   const instance = require('..')()
   instance.flush()
 })
+
+test('thread-stream async flush', async () => {
+  const pino = require('..')
+  const transport = pino.transport({
+    target: join(__dirname, 'fixtures', 'console-transport.js')
+  })
+  const instance = pino(transport)
+  instance.info('hello')
+  instance.flush()
+})

test/targets.test.js

@@ -8,7 +8,7 @@ test('file-target mocked', async function ({ equal, same, plan, pass }) {
   plan(1)
   let ret
   const fileTarget = proxyquire('../file', {
-    '../pino': {
+    './pino': {
       destination (opts) {
         same(opts, { dest: 1, sync: false })