Fixes #1167 (dedupe should write to all streams matching the target level)

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 () {

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'