From 9cc90e37b18dda7bc305b4915df17c7a78f41551 Mon Sep 17 00:00:00 2001
From: Zsombor Franczia <me@frzsombor.com>
Date: Tue, 19 Oct 2021 09:41:31 +0200
Subject: [PATCH] Fixes #1167 (dedupe should write to all streams matching the
 target level) (#1172)

---
 lib/multistream.js       |  6 +-----
 test/multistream.test.js | 42 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/lib/multistream.js b/lib/multistream.js
index 69819b0b9..96527986b 100644
--- a/lib/multistream.js
+++ b/lib/multistream.js
@@ -59,17 +59,13 @@ function multistream (streamsArray, opts) {
           stream.lastObj = lastObj
           stream.lastLogger = lastLogger
         }
-        if (!opts.dedupe) {
+        if (!opts.dedupe || dest.level === level) {
           stream.write(data)
         }
       } else {
         break
       }
     }
-
-    if (opts.dedupe && stream) {
-      stream.write(data)
-    }
   }
 
   function flushSync () {
diff --git a/test/multistream.test.js b/test/multistream.test.js
index ff363d3cb..94ae848bf 100644
--- a/test/multistream.test.js
+++ b/test/multistream.test.js
@@ -429,6 +429,48 @@ test('dedupe', function (t) {
   t.end()
 })
 
+test('dedupe when some streams has the same level', function (t) {
+  let messageCount = 0
+  const stream1 = writeStream(function (data, enc, cb) {
+    messageCount -= 1
+    cb()
+  })
+
+  const stream2 = writeStream(function (data, enc, cb) {
+    messageCount += 1
+    cb()
+  })
+
+  const stream3 = writeStream(function (data, enc, cb) {
+    messageCount += 1
+    cb()
+  })
+
+  const streams = [
+    {
+      stream: stream1,
+      level: 'info'
+    },
+    {
+      stream: stream2,
+      level: 'fatal'
+    },
+    {
+      stream: stream3,
+      level: 'fatal'
+    }
+  ]
+
+  const log = pino({
+    level: 'trace'
+  }, multistream(streams, { dedupe: true }))
+  log.info('info stream')
+  log.fatal('fatal streams')
+  log.fatal('fatal streams')
+  t.equal(messageCount, 3)
+  t.end()
+})
+
 test('no stream', function (t) {
   const log = pino({
     level: 'trace'