fix: don't leak socket listener (#431)

Fixes: #430

lib/core/client.js

@@ -1102,10 +1102,6 @@ function write (client, request) {
     const onAbort = function () {
       onFinished(new RequestAbortedError())
     }
-    /* istanbul ignore next */
-    const onClose = function () {
-      assert(false, 'socket should not close without error')
-    }
     const onFinished = function (err) {
       if (finished) {
         return
@@ -1123,7 +1119,6 @@ function write (client, request) {
       socket
         .removeListener('drain', onDrain)
         .removeListener('error', onFinished)
-        .removeListener('close', onClose)
       body
         .removeListener('data', onData)
         .removeListener('end', onFinished)
@@ -1165,7 +1160,6 @@ function write (client, request) {
     socket
       .on('drain', onDrain)
       .on('error', onFinished)
-      .on('close', onFinished)
   }
 
   return true

test/client-write-max-listeners.js

@@ -0,0 +1,49 @@
+'use strict'
+
+const { test } = require('tap')
+const { Client } = require('..')
+const { createServer } = require('http')
+const { Readable } = require('stream')
+
+test('socket close listener does not leak', (t) => {
+  t.plan(32)
+
+  const server = createServer()
+
+  server.on('request', (req, res) => {
+    res.end('hello')
+  })
+  t.tearDown(server.close.bind(server))
+
+  const makeBody = () => {
+    return new Readable({
+      read () {
+        process.nextTick(() => {
+          this.push(null)
+        })
+      }
+    })
+  }
+
+  const onRequest = (err, data) => {
+    t.error(err)
+    data.body.on('end', () => t.pass()).resume()
+  }
+
+  process.on('warning', () => {
+    t.fail()
+  })
+
+  server.listen(0, () => {
+    const client = new Client(`http://localhost:${server.address().port}`)
+    t.tearDown(client.destroy.bind(client))
+
+    client.on('disconnect', () => {
+      t.fail()
+    })
+
+    for (let n = 0; n < 16; ++n) {
+      client.request({ path: '/', method: 'GET', body: makeBody() }, onRequest)
+    }
+  })
+})