From 143bb0afbce8cd65a281784b8291aadb2b4f51f0 Mon Sep 17 00:00:00 2001
From: Carlos Fuentes <me@metcoder.dev>
Date: Wed, 3 Jan 2024 12:24:14 +0100
Subject: [PATCH 01/10] feat: add debug support through diagnostics channel

---
 lib/core/diagnostics.js | 214 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 214 insertions(+)
 create mode 100644 lib/core/diagnostics.js

diff --git a/lib/core/diagnostics.js b/lib/core/diagnostics.js
new file mode 100644
index 00000000000..e97207c6108
--- /dev/null
+++ b/lib/core/diagnostics.js
@@ -0,0 +1,214 @@
+let channels
+try {
+  const diagnosticsChannel = require('diagnostics_channel')
+  let isClientSet = false
+  channels = {
+    // Client
+    beforeConnect: diagnosticsChannel.channel('undici:client:beforeConnect'),
+    connected: diagnosticsChannel.channel('undici:client:connected'),
+    connectError: diagnosticsChannel.channel('undici:client:connectError'),
+    sendHeaders: diagnosticsChannel.channel('undici:client:sendHeaders'),
+    // Request
+    create: diagnosticsChannel.channel('undici:request:create'),
+    bodySent: diagnosticsChannel.channel('undici:request:bodySent'),
+    headers: diagnosticsChannel.channel('undici:request:headers'),
+    trailers: diagnosticsChannel.channel('undici:request:trailers'),
+    error: diagnosticsChannel.channel('undici:request:error'),
+    // WebSocket
+    open: diagnosticsChannel.channel('undici:websocket:open'),
+    close: diagnosticsChannel.channel('undici:websocket:close'),
+    socketError: diagnosticsChannel.channel('undici:websocket:socket_error'),
+    ping: diagnosticsChannel.channel('undici:websocket:ping'),
+    pong: diagnosticsChannel.channel('undici:websocket:pong')
+  }
+
+  if (process.env.NODE_DEBUG.match(/(fetch|undici)/) != null) {
+    // Track all Client events
+    diagnosticsChannel.channel('undici:client:beforeConnect').subscribe(evt => {
+      const {
+        connectParams: { version, protocol, port, host }
+      } = evt
+      console.log(
+        `HTTP:undici ${process.pid}: connecting to ${host}${
+          port ? `:${port}` : ''
+        } using ${protocol}${version}`
+      )
+    })
+
+    diagnosticsChannel.channel('undici:client:connected').subscribe(evt => {
+      const {
+        connectParams: { version, protocol, port, host }
+      } = evt
+      console.log(
+        `HTTP:undici ${process.pid}: connected to ${host}${
+          port ? `:${port}` : ''
+        } using ${protocol}${version}`
+      )
+    })
+
+    diagnosticsChannel.channel('undici:client:connectError').subscribe(evt => {
+      const {
+        connectParams: { version, protocol, port, host },
+        error
+      } = evt
+      console.log(
+        `HTTP:undici ${process.pid}: connection to ${host}${
+          port ? `:${port}` : ''
+        } using ${protocol}${version} errored - ${error.message}`
+      )
+    })
+
+    diagnosticsChannel.channel('undici:client:sendHeaders').subscribe(evt => {
+      const {
+        request: { method, path, origin }
+      } = evt
+      console.log(
+        `HTTP:undici ${process.pid}: sending request to ${method} ${origin}/${path}`
+      )
+    })
+
+    // Track Request events
+    diagnosticsChannel.channel('undici:request:headers').subscribe(evt => {
+      const {
+        request: { method, path, origin },
+        response: { statusCode }
+      } = evt
+      console.log(
+        `HTTP:undici ${process.pid}: received response ${method} ${origin}/${path} - HTTP ${statusCode}`
+      )
+    })
+
+    diagnosticsChannel.channel('undici:request:trailers').subscribe(evt => {
+      const {
+        request: { method, path, origin }
+      } = evt
+      console.log(
+        `HTTP:undici ${process.pid}: trailers received from ${method} ${origin}/${path}`
+      )
+    })
+
+    diagnosticsChannel.channel('undici:request:error').subscribe(evt => {
+      const {
+        request: { method, path, origin },
+        error
+      } = evt
+      console.log(
+        `HTTP:undici ${process.pid}: request errored ${method} ${origin}/${path} - ${error.message}`
+      )
+    })
+
+    isClientSet = true
+  }
+
+  if (process.env.NODE_DEBUG.match(/websocket/) != null) {
+    if (!isClientSet) {
+      diagnosticsChannel
+        .channel('undici:client:beforeConnect')
+        .subscribe(evt => {
+          const {
+            connectParams: { version, protocol, port, host }
+          } = evt
+          console.log(
+            `HTTP:undici ${process.pid}: connecting to ${host}${
+              port ? `:${port}` : ''
+            } using ${protocol}${version}`
+          )
+        })
+
+      diagnosticsChannel.channel('undici:client:connected').subscribe(evt => {
+        const {
+          connectParams: { version, protocol, port, host }
+        } = evt
+        console.log(
+          `HTTP:undici ${process.pid}: connected to ${host}${
+            port ? `:${port}` : ''
+          } using ${protocol}${version}`
+        )
+      })
+
+      diagnosticsChannel
+        .channel('undici:client:connectError')
+        .subscribe(evt => {
+          const {
+            connectParams: { version, protocol, port, host },
+            error
+          } = evt
+          console.log(
+            `HTTP:undici ${process.pid}: connection to ${host}${
+              port ? `:${port}` : ''
+            } using ${protocol}${version} errored - ${error.message}`
+          )
+        })
+
+      diagnosticsChannel.channel('undici:client:sendHeaders').subscribe(evt => {
+        const {
+          request: { method, path, origin }
+        } = evt
+        console.log(
+          `HTTP:undici ${process.pid}: sending request to ${method} ${origin}/${path}`
+        )
+      })
+    }
+
+    // Track all Client events
+    diagnosticsChannel.channel('undici:websocket:open').subscribe(evt => {
+      const {
+        address: { address, port },
+        protocol,
+        extensions
+      } = evt
+      console.log(
+        `WebSocket:undici ${process.pid}: connection opened ${address}${
+          port ? `:${port}` : ''
+        } using ${protocol}-${extensions}`
+      )
+    })
+
+    diagnosticsChannel.channel('undici:websocket:close').subscribe(evt => {
+      const { websocket, code, reason } = evt
+      console.log(
+        `WebSocket:undici ${process.pid}: closed connection to ${websocket.url} - ${code} ${reason}`
+      )
+    })
+
+    diagnosticsChannel
+      .channel('undici:websocket:socket_error')
+      .subscribe(err => {
+        console.log(
+          `WebSocket:undici ${process.pid}: connection errored - ${err.message}`
+        )
+      })
+
+    diagnosticsChannel.channel('undici:websocket:ping').subscribe(evt => {
+      console.log(`WebSocket:undici ${process.pid}: ping received`)
+    })
+
+    diagnosticsChannel.channel('undici:websocket:pong').subscribe(evt => {
+      console.log(`WebSocket:undici ${process.pid}: pong received`)
+    })
+  }
+} catch (error) {
+  channels = {
+    // Client
+    sendHeaders: { hasSubcribers: false },
+    beforeConnect: { hasSubcribers: false },
+    connectError: { hasSubcribers: false },
+    connected: { hasSubcribers: false },
+    // Request
+    create: { hasSubcribers: false },
+    bodySent: { hasSubcribers: false },
+    headers: { hasSubcribers: false },
+    trailers: { hasSubcribers: false },
+    error: { hasSubcribers: false },
+    // WebSocket
+    open: { hasSubcribers: false },
+    close: { hasSubcribers: false },
+    socketError: { hasSubcribers: false },
+    ping: { hasSubcribers: false },
+    pong: { hasSubcribers: false }
+  }
+}
+
+module.exports = {
+  channels
+}

From 67be3a8800e01e012899b4895be28c1983770986 Mon Sep 17 00:00:00 2001
From: Carlos Fuentes <me@metcoder.dev>
Date: Wed, 3 Jan 2024 12:24:56 +0100
Subject: [PATCH 02/10] refactor: replace old diagnostics with new abstraction

---
 lib/client.js               | 31 +++++++++++++++++--------------
 lib/core/request.js         | 31 ++++++++++++++++---------------
 lib/websocket/connection.js | 10 +++++-----
 lib/websocket/receiver.js   |  8 ++++----
 4 files changed, 42 insertions(+), 38 deletions(-)

diff --git a/lib/client.js b/lib/client.js
index 25f3478490e..377e2e4d52f 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -9,6 +9,7 @@ const net = require('net')
 const http = require('http')
 const { pipeline } = require('stream')
 const util = require('./core/util')
+const { channels } = require('./core/diagnostics')
 const timers = require('./timers')
 const Request = require('./core/request')
 const DispatcherBase = require('./dispatcher-base')
@@ -108,20 +109,20 @@ const FastBuffer = Buffer[Symbol.species]
 
 const kClosedResolve = Symbol('kClosedResolve')
 
-const channels = {}
-
-try {
-  const diagnosticsChannel = require('diagnostics_channel')
-  channels.sendHeaders = diagnosticsChannel.channel('undici:client:sendHeaders')
-  channels.beforeConnect = diagnosticsChannel.channel('undici:client:beforeConnect')
-  channels.connectError = diagnosticsChannel.channel('undici:client:connectError')
-  channels.connected = diagnosticsChannel.channel('undici:client:connected')
-} catch {
-  channels.sendHeaders = { hasSubscribers: false }
-  channels.beforeConnect = { hasSubscribers: false }
-  channels.connectError = { hasSubscribers: false }
-  channels.connected = { hasSubscribers: false }
-}
+// const channels = {}
+
+// try {
+//   const diagnosticsChannel = require('diagnostics_channel')
+//   channels.sendHeaders = diagnosticsChannel.channel('undici:client:sendHeaders')
+//   channels.beforeConnect = diagnosticsChannel.channel('undici:client:beforeConnect')
+//   channels.connectError = diagnosticsChannel.channel('undici:client:connectError')
+//   channels.connected = diagnosticsChannel.channel('undici:client:connected')
+// } catch {
+//   channels.sendHeaders = { hasSubscribers: false }
+//   channels.beforeConnect = { hasSubscribers: false }
+//   channels.connectError = { hasSubscribers: false }
+//   channels.connected = { hasSubscribers: false }
+// }
 
 /**
  * @type {import('../types/client').default}
@@ -1191,6 +1192,7 @@ async function connect (client) {
         hostname,
         protocol,
         port,
+        version: client[kHTTPConnVersion],
         servername: client[kServerName],
         localAddress: client[kLocalAddress]
       },
@@ -1284,6 +1286,7 @@ async function connect (client) {
           hostname,
           protocol,
           port,
+          version: client[kHTTPConnVersion],
           servername: client[kServerName],
           localAddress: client[kLocalAddress]
         },
diff --git a/lib/core/request.js b/lib/core/request.js
index fe63434ea98..dc706fc1981 100644
--- a/lib/core/request.js
+++ b/lib/core/request.js
@@ -7,6 +7,7 @@ const {
 const assert = require('assert')
 const { kHTTP2BuildRequest, kHTTP2CopyHeaders, kHTTP1BuildRequest } = require('./symbols')
 const util = require('./util')
+const { channels } = require('./diagnostics.js')
 const { headerNameLowerCasedRecord } = require('./constants')
 
 // headerCharRegex have been lifted from
@@ -25,24 +26,24 @@ const invalidPathRegex = /[^\u0021-\u00ff]/
 
 const kHandler = Symbol('handler')
 
-const channels = {}
+// const channels = {}
 
 let extractBody
 
-try {
-  const diagnosticsChannel = require('diagnostics_channel')
-  channels.create = diagnosticsChannel.channel('undici:request:create')
-  channels.bodySent = diagnosticsChannel.channel('undici:request:bodySent')
-  channels.headers = diagnosticsChannel.channel('undici:request:headers')
-  channels.trailers = diagnosticsChannel.channel('undici:request:trailers')
-  channels.error = diagnosticsChannel.channel('undici:request:error')
-} catch {
-  channels.create = { hasSubscribers: false }
-  channels.bodySent = { hasSubscribers: false }
-  channels.headers = { hasSubscribers: false }
-  channels.trailers = { hasSubscribers: false }
-  channels.error = { hasSubscribers: false }
-}
+// try {
+//   const diagnosticsChannel = require('diagnostics_channel')
+//   channels.create = diagnosticsChannel.channel('undici:request:create')
+//   channels.bodySent = diagnosticsChannel.channel('undici:request:bodySent')
+//   channels.headers = diagnosticsChannel.channel('undici:request:headers')
+//   channels.trailers = diagnosticsChannel.channel('undici:request:trailers')
+//   channels.error = diagnosticsChannel.channel('undici:request:error')
+// } catch {
+//   channels.create = { hasSubscribers: false }
+//   channels.bodySent = { hasSubscribers: false }
+//   channels.headers = { hasSubscribers: false }
+//   channels.trailers = { hasSubscribers: false }
+//   channels.error = { hasSubscribers: false }
+// }
 
 class Request {
   constructor (origin, {
diff --git a/lib/websocket/connection.js b/lib/websocket/connection.js
index 4bc60b3b90b..7ca9b176ed5 100644
--- a/lib/websocket/connection.js
+++ b/lib/websocket/connection.js
@@ -1,6 +1,5 @@
 'use strict'
 
-const diagnosticsChannel = require('diagnostics_channel')
 const { uid, states } = require('./constants')
 const {
   kReadyState,
@@ -9,6 +8,7 @@ const {
   kReceivedClose
 } = require('./symbols')
 const { fireEvent, failWebsocketConnection } = require('./util')
+const { channels } = require('../core/diagnostics')
 const { CloseEvent } = require('./events')
 const { makeRequest } = require('../fetch/request')
 const { fetching } = require('../fetch/index')
@@ -16,10 +16,10 @@ const { Headers } = require('../fetch/headers')
 const { getGlobalDispatcher } = require('../global')
 const { kHeadersList } = require('../core/symbols')
 
-const channels = {}
-channels.open = diagnosticsChannel.channel('undici:websocket:open')
-channels.close = diagnosticsChannel.channel('undici:websocket:close')
-channels.socketError = diagnosticsChannel.channel('undici:websocket:socket_error')
+// const channels = {}
+// channels.open = diagnosticsChannel.channel('undici:websocket:open')
+// channels.close = diagnosticsChannel.channel('undici:websocket:close')
+// channels.socketError = diagnosticsChannel.channel('undici:websocket:socket_error')
 
 /** @type {import('crypto')} */
 let crypto
diff --git a/lib/websocket/receiver.js b/lib/websocket/receiver.js
index bdd2031b418..4822bcf9531 100644
--- a/lib/websocket/receiver.js
+++ b/lib/websocket/receiver.js
@@ -1,9 +1,9 @@
 'use strict'
 
 const { Writable } = require('stream')
-const diagnosticsChannel = require('diagnostics_channel')
 const { parserStates, opcodes, states, emptyBuffer } = require('./constants')
 const { kReadyState, kSentClose, kResponse, kReceivedClose } = require('./symbols')
+const { channels } = require('../core/diagnostics')
 const { isValidStatusCode, failWebsocketConnection, websocketMessageReceived } = require('./util')
 const { WebsocketFrameSend } = require('./frame')
 
@@ -12,9 +12,9 @@ const { WebsocketFrameSend } = require('./frame')
 // Copyright (c) 2013 Arnout Kazemier and contributors
 // Copyright (c) 2016 Luigi Pinca and contributors
 
-const channels = {}
-channels.ping = diagnosticsChannel.channel('undici:websocket:ping')
-channels.pong = diagnosticsChannel.channel('undici:websocket:pong')
+// const channels = {}
+// channels.ping = diagnosticsChannel.channel('undici:websocket:ping')
+// channels.pong = diagnosticsChannel.channel('undici:websocket:pong')
 
 class ByteParser extends Writable {
   #buffers = []

From 5750b6e340e04545ac7ce6fbe6c10437913314a7 Mon Sep 17 00:00:00 2001
From: Carlos Fuentes <me@metcoder.dev>
Date: Fri, 5 Jan 2024 10:36:16 +0100
Subject: [PATCH 03/10] refactor: handle diagnostics simpler

---
 lib/core/diagnostics.js | 300 ++++++++++++++++++----------------------
 1 file changed, 136 insertions(+), 164 deletions(-)

diff --git a/lib/core/diagnostics.js b/lib/core/diagnostics.js
index e97207c6108..16c3c8e1dc2 100644
--- a/lib/core/diagnostics.js
+++ b/lib/core/diagnostics.js
@@ -1,29 +1,106 @@
-let channels
-try {
-  const diagnosticsChannel = require('diagnostics_channel')
-  let isClientSet = false
-  channels = {
-    // Client
-    beforeConnect: diagnosticsChannel.channel('undici:client:beforeConnect'),
-    connected: diagnosticsChannel.channel('undici:client:connected'),
-    connectError: diagnosticsChannel.channel('undici:client:connectError'),
-    sendHeaders: diagnosticsChannel.channel('undici:client:sendHeaders'),
-    // Request
-    create: diagnosticsChannel.channel('undici:request:create'),
-    bodySent: diagnosticsChannel.channel('undici:request:bodySent'),
-    headers: diagnosticsChannel.channel('undici:request:headers'),
-    trailers: diagnosticsChannel.channel('undici:request:trailers'),
-    error: diagnosticsChannel.channel('undici:request:error'),
-    // WebSocket
-    open: diagnosticsChannel.channel('undici:websocket:open'),
-    close: diagnosticsChannel.channel('undici:websocket:close'),
-    socketError: diagnosticsChannel.channel('undici:websocket:socket_error'),
-    ping: diagnosticsChannel.channel('undici:websocket:ping'),
-    pong: diagnosticsChannel.channel('undici:websocket:pong')
-  }
+const diagnosticsChannel = require('diagnostics_channel')
+
+let isClientSet = false
+const channels = {
+  // Client
+  beforeConnect: diagnosticsChannel.channel('undici:client:beforeConnect'),
+  connected: diagnosticsChannel.channel('undici:client:connected'),
+  connectError: diagnosticsChannel.channel('undici:client:connectError'),
+  sendHeaders: diagnosticsChannel.channel('undici:client:sendHeaders'),
+  // Request
+  create: diagnosticsChannel.channel('undici:request:create'),
+  bodySent: diagnosticsChannel.channel('undici:request:bodySent'),
+  headers: diagnosticsChannel.channel('undici:request:headers'),
+  trailers: diagnosticsChannel.channel('undici:request:trailers'),
+  error: diagnosticsChannel.channel('undici:request:error'),
+  // WebSocket
+  open: diagnosticsChannel.channel('undici:websocket:open'),
+  close: diagnosticsChannel.channel('undici:websocket:close'),
+  socketError: diagnosticsChannel.channel('undici:websocket:socket_error'),
+  ping: diagnosticsChannel.channel('undici:websocket:ping'),
+  pong: diagnosticsChannel.channel('undici:websocket:pong')
+}
+
+if (process.env.NODE_DEBUG?.match(/(fetch|undici)/) != null) {
+  // Track all Client events
+  diagnosticsChannel.channel('undici:client:beforeConnect').subscribe(evt => {
+    const {
+      connectParams: { version, protocol, port, host }
+    } = evt
+    console.log(
+      `HTTP:undici ${process.pid}: connecting to ${host}${
+        port ? `:${port}` : ''
+      } using ${protocol}${version}`
+    )
+  })
+
+  diagnosticsChannel.channel('undici:client:connected').subscribe(evt => {
+    const {
+      connectParams: { version, protocol, port, host }
+    } = evt
+    console.log(
+      `HTTP:undici ${process.pid}: connected to ${host}${
+        port ? `:${port}` : ''
+      } using ${protocol}${version}`
+    )
+  })
+
+  diagnosticsChannel.channel('undici:client:connectError').subscribe(evt => {
+    const {
+      connectParams: { version, protocol, port, host },
+      error
+    } = evt
+    console.log(
+      `HTTP:undici ${process.pid}: connection to ${host}${
+        port ? `:${port}` : ''
+      } using ${protocol}${version} errored - ${error.message}`
+    )
+  })
+
+  diagnosticsChannel.channel('undici:client:sendHeaders').subscribe(evt => {
+    const {
+      request: { method, path, origin }
+    } = evt
+    console.log(
+      `HTTP:undici ${process.pid}: sending request to ${method} ${origin}/${path}`
+    )
+  })
+
+  // Track Request events
+  diagnosticsChannel.channel('undici:request:headers').subscribe(evt => {
+    const {
+      request: { method, path, origin },
+      response: { statusCode }
+    } = evt
+    console.log(
+      `HTTP:undici ${process.pid}: received response ${method} ${origin}/${path} - HTTP ${statusCode}`
+    )
+  })
+
+  diagnosticsChannel.channel('undici:request:trailers').subscribe(evt => {
+    const {
+      request: { method, path, origin }
+    } = evt
+    console.log(
+      `HTTP:undici ${process.pid}: trailers received from ${method} ${origin}/${path}`
+    )
+  })
+
+  diagnosticsChannel.channel('undici:request:error').subscribe(evt => {
+    const {
+      request: { method, path, origin },
+      error
+    } = evt
+    console.log(
+      `HTTP:undici ${process.pid}: request errored ${method} ${origin}/${path} - ${error.message}`
+    )
+  })
+
+  isClientSet = true
+}
 
-  if (process.env.NODE_DEBUG.match(/(fetch|undici)/) != null) {
-    // Track all Client events
+if (process.env.NODE_DEBUG?.match(/websocket/) != null) {
+  if (!isClientSet) {
     diagnosticsChannel.channel('undici:client:beforeConnect').subscribe(evt => {
       const {
         connectParams: { version, protocol, port, host }
@@ -66,147 +143,42 @@ try {
         `HTTP:undici ${process.pid}: sending request to ${method} ${origin}/${path}`
       )
     })
-
-    // Track Request events
-    diagnosticsChannel.channel('undici:request:headers').subscribe(evt => {
-      const {
-        request: { method, path, origin },
-        response: { statusCode }
-      } = evt
-      console.log(
-        `HTTP:undici ${process.pid}: received response ${method} ${origin}/${path} - HTTP ${statusCode}`
-      )
-    })
-
-    diagnosticsChannel.channel('undici:request:trailers').subscribe(evt => {
-      const {
-        request: { method, path, origin }
-      } = evt
-      console.log(
-        `HTTP:undici ${process.pid}: trailers received from ${method} ${origin}/${path}`
-      )
-    })
-
-    diagnosticsChannel.channel('undici:request:error').subscribe(evt => {
-      const {
-        request: { method, path, origin },
-        error
-      } = evt
-      console.log(
-        `HTTP:undici ${process.pid}: request errored ${method} ${origin}/${path} - ${error.message}`
-      )
-    })
-
-    isClientSet = true
   }
 
-  if (process.env.NODE_DEBUG.match(/websocket/) != null) {
-    if (!isClientSet) {
-      diagnosticsChannel
-        .channel('undici:client:beforeConnect')
-        .subscribe(evt => {
-          const {
-            connectParams: { version, protocol, port, host }
-          } = evt
-          console.log(
-            `HTTP:undici ${process.pid}: connecting to ${host}${
-              port ? `:${port}` : ''
-            } using ${protocol}${version}`
-          )
-        })
-
-      diagnosticsChannel.channel('undici:client:connected').subscribe(evt => {
-        const {
-          connectParams: { version, protocol, port, host }
-        } = evt
-        console.log(
-          `HTTP:undici ${process.pid}: connected to ${host}${
-            port ? `:${port}` : ''
-          } using ${protocol}${version}`
-        )
-      })
-
-      diagnosticsChannel
-        .channel('undici:client:connectError')
-        .subscribe(evt => {
-          const {
-            connectParams: { version, protocol, port, host },
-            error
-          } = evt
-          console.log(
-            `HTTP:undici ${process.pid}: connection to ${host}${
-              port ? `:${port}` : ''
-            } using ${protocol}${version} errored - ${error.message}`
-          )
-        })
-
-      diagnosticsChannel.channel('undici:client:sendHeaders').subscribe(evt => {
-        const {
-          request: { method, path, origin }
-        } = evt
-        console.log(
-          `HTTP:undici ${process.pid}: sending request to ${method} ${origin}/${path}`
-        )
-      })
-    }
-
-    // Track all Client events
-    diagnosticsChannel.channel('undici:websocket:open').subscribe(evt => {
-      const {
-        address: { address, port },
-        protocol,
-        extensions
-      } = evt
-      console.log(
-        `WebSocket:undici ${process.pid}: connection opened ${address}${
-          port ? `:${port}` : ''
-        } using ${protocol}-${extensions}`
-      )
-    })
-
-    diagnosticsChannel.channel('undici:websocket:close').subscribe(evt => {
-      const { websocket, code, reason } = evt
-      console.log(
-        `WebSocket:undici ${process.pid}: closed connection to ${websocket.url} - ${code} ${reason}`
-      )
-    })
-
-    diagnosticsChannel
-      .channel('undici:websocket:socket_error')
-      .subscribe(err => {
-        console.log(
-          `WebSocket:undici ${process.pid}: connection errored - ${err.message}`
-        )
-      })
-
-    diagnosticsChannel.channel('undici:websocket:ping').subscribe(evt => {
-      console.log(`WebSocket:undici ${process.pid}: ping received`)
-    })
-
-    diagnosticsChannel.channel('undici:websocket:pong').subscribe(evt => {
-      console.log(`WebSocket:undici ${process.pid}: pong received`)
-    })
-  }
-} catch (error) {
-  channels = {
-    // Client
-    sendHeaders: { hasSubcribers: false },
-    beforeConnect: { hasSubcribers: false },
-    connectError: { hasSubcribers: false },
-    connected: { hasSubcribers: false },
-    // Request
-    create: { hasSubcribers: false },
-    bodySent: { hasSubcribers: false },
-    headers: { hasSubcribers: false },
-    trailers: { hasSubcribers: false },
-    error: { hasSubcribers: false },
-    // WebSocket
-    open: { hasSubcribers: false },
-    close: { hasSubcribers: false },
-    socketError: { hasSubcribers: false },
-    ping: { hasSubcribers: false },
-    pong: { hasSubcribers: false }
-  }
+  // Track all WebSocket events
+  diagnosticsChannel.channel('undici:websocket:open').subscribe(evt => {
+    const {
+      address: { address, port },
+      protocol,
+      extensions
+    } = evt
+    console.log(
+      `WebSocket:undici ${process.pid}: connection opened ${address}${
+        port ? `:${port}` : ''
+      } using ${protocol}-${extensions}`
+    )
+  })
+
+  diagnosticsChannel.channel('undici:websocket:close').subscribe(evt => {
+    const { websocket, code, reason } = evt
+    console.log(
+      `WebSocket:undici ${process.pid}: closed connection to ${websocket.url} - ${code} ${reason}`
+    )
+  })
+
+  diagnosticsChannel.channel('undici:websocket:socket_error').subscribe(err => {
+    console.log(
+      `WebSocket:undici ${process.pid}: connection errored - ${err.message}`
+    )
+  })
+
+  diagnosticsChannel.channel('undici:websocket:ping').subscribe(evt => {
+    console.log(`WebSocket:undici ${process.pid}: ping received`)
+  })
+
+  diagnosticsChannel.channel('undici:websocket:pong').subscribe(evt => {
+    console.log(`WebSocket:undici ${process.pid}: pong received`)
+  })
 }
 
 module.exports = {

From f0c25e89f510740601362de890015cfe4af4ff51 Mon Sep 17 00:00:00 2001
From: Carlos Fuentes <me@metcoder.dev>
Date: Fri, 5 Jan 2024 10:43:27 +0100
Subject: [PATCH 04/10] test: move tests to 'right' path

---
 test/{ => node-test}/diagnostics-channel/connect-error.js | 2 +-
 test/{ => node-test}/diagnostics-channel/error.js         | 0
 test/{ => node-test}/diagnostics-channel/get.js           | 0
 test/{ => node-test}/diagnostics-channel/post-stream.js   | 0
 test/{ => node-test}/diagnostics-channel/post.js          | 2 +-
 5 files changed, 2 insertions(+), 2 deletions(-)
 rename test/{ => node-test}/diagnostics-channel/connect-error.js (97%)
 rename test/{ => node-test}/diagnostics-channel/error.js (100%)
 rename test/{ => node-test}/diagnostics-channel/get.js (100%)
 rename test/{ => node-test}/diagnostics-channel/post-stream.js (100%)
 rename test/{ => node-test}/diagnostics-channel/post.js (99%)

diff --git a/test/diagnostics-channel/connect-error.js b/test/node-test/diagnostics-channel/connect-error.js
similarity index 97%
rename from test/diagnostics-channel/connect-error.js
rename to test/node-test/diagnostics-channel/connect-error.js
index a3bf2a45de7..35559fab86a 100644
--- a/test/diagnostics-channel/connect-error.js
+++ b/test/node-test/diagnostics-channel/connect-error.js
@@ -12,7 +12,7 @@ try {
   process.exit(0)
 }
 
-const { Client } = require('../..')
+const { Client } = require('../../..')
 
 test('Diagnostics channel - connect error', (t) => {
   const connectError = new Error('custom error')
diff --git a/test/diagnostics-channel/error.js b/test/node-test/diagnostics-channel/error.js
similarity index 100%
rename from test/diagnostics-channel/error.js
rename to test/node-test/diagnostics-channel/error.js
diff --git a/test/diagnostics-channel/get.js b/test/node-test/diagnostics-channel/get.js
similarity index 100%
rename from test/diagnostics-channel/get.js
rename to test/node-test/diagnostics-channel/get.js
diff --git a/test/diagnostics-channel/post-stream.js b/test/node-test/diagnostics-channel/post-stream.js
similarity index 100%
rename from test/diagnostics-channel/post-stream.js
rename to test/node-test/diagnostics-channel/post-stream.js
diff --git a/test/diagnostics-channel/post.js b/test/node-test/diagnostics-channel/post.js
similarity index 99%
rename from test/diagnostics-channel/post.js
rename to test/node-test/diagnostics-channel/post.js
index 30203a7e7c7..1f0475bd556 100644
--- a/test/diagnostics-channel/post.js
+++ b/test/node-test/diagnostics-channel/post.js
@@ -12,7 +12,7 @@ try {
   process.exit(0)
 }
 
-const { Client } = require('../..')
+const { Client } = require('../../..')
 const { createServer } = require('http')
 
 test('Diagnostics channel - post', (t) => {

From 97ddbc3d8c979969b9b9202e98da88529bc0a67e Mon Sep 17 00:00:00 2001
From: Carlos Fuentes <me@metcoder.dev>
Date: Fri, 5 Jan 2024 11:14:46 +0100
Subject: [PATCH 05/10] fix: smaller tweaks

---
 lib/client.js                                   | 16 +---------------
 lib/core/request.js                             | 17 -----------------
 lib/websocket/connection.js                     |  5 -----
 lib/websocket/receiver.js                       |  4 ----
 package.json                                    |  7 ++++---
 .../diagnostics-channel/connect-error.js        |  4 ++--
 test/node-test/diagnostics-channel/error.js     |  2 +-
 test/node-test/diagnostics-channel/get.js       |  6 +++---
 .../diagnostics-channel/post-stream.js          |  6 +++---
 test/node-test/diagnostics-channel/post.js      |  6 +++---
 10 files changed, 17 insertions(+), 56 deletions(-)

diff --git a/lib/client.js b/lib/client.js
index 377e2e4d52f..cc5c4890552 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -109,21 +109,6 @@ const FastBuffer = Buffer[Symbol.species]
 
 const kClosedResolve = Symbol('kClosedResolve')
 
-// const channels = {}
-
-// try {
-//   const diagnosticsChannel = require('diagnostics_channel')
-//   channels.sendHeaders = diagnosticsChannel.channel('undici:client:sendHeaders')
-//   channels.beforeConnect = diagnosticsChannel.channel('undici:client:beforeConnect')
-//   channels.connectError = diagnosticsChannel.channel('undici:client:connectError')
-//   channels.connected = diagnosticsChannel.channel('undici:client:connected')
-// } catch {
-//   channels.sendHeaders = { hasSubscribers: false }
-//   channels.beforeConnect = { hasSubscribers: false }
-//   channels.connectError = { hasSubscribers: false }
-//   channels.connected = { hasSubscribers: false }
-// }
-
 /**
  * @type {import('../types/client').default}
  */
@@ -1309,6 +1294,7 @@ async function connect (client) {
           hostname,
           protocol,
           port,
+          version: client[kHTTPConnVersion],
           servername: client[kServerName],
           localAddress: client[kLocalAddress]
         },
diff --git a/lib/core/request.js b/lib/core/request.js
index dc706fc1981..4a61da0e454 100644
--- a/lib/core/request.js
+++ b/lib/core/request.js
@@ -26,25 +26,8 @@ const invalidPathRegex = /[^\u0021-\u00ff]/
 
 const kHandler = Symbol('handler')
 
-// const channels = {}
-
 let extractBody
 
-// try {
-//   const diagnosticsChannel = require('diagnostics_channel')
-//   channels.create = diagnosticsChannel.channel('undici:request:create')
-//   channels.bodySent = diagnosticsChannel.channel('undici:request:bodySent')
-//   channels.headers = diagnosticsChannel.channel('undici:request:headers')
-//   channels.trailers = diagnosticsChannel.channel('undici:request:trailers')
-//   channels.error = diagnosticsChannel.channel('undici:request:error')
-// } catch {
-//   channels.create = { hasSubscribers: false }
-//   channels.bodySent = { hasSubscribers: false }
-//   channels.headers = { hasSubscribers: false }
-//   channels.trailers = { hasSubscribers: false }
-//   channels.error = { hasSubscribers: false }
-// }
-
 class Request {
   constructor (origin, {
     path,
diff --git a/lib/websocket/connection.js b/lib/websocket/connection.js
index 7ca9b176ed5..d8a4f04f637 100644
--- a/lib/websocket/connection.js
+++ b/lib/websocket/connection.js
@@ -16,11 +16,6 @@ const { Headers } = require('../fetch/headers')
 const { getGlobalDispatcher } = require('../global')
 const { kHeadersList } = require('../core/symbols')
 
-// const channels = {}
-// channels.open = diagnosticsChannel.channel('undici:websocket:open')
-// channels.close = diagnosticsChannel.channel('undici:websocket:close')
-// channels.socketError = diagnosticsChannel.channel('undici:websocket:socket_error')
-
 /** @type {import('crypto')} */
 let crypto
 try {
diff --git a/lib/websocket/receiver.js b/lib/websocket/receiver.js
index 4822bcf9531..512ef42a06b 100644
--- a/lib/websocket/receiver.js
+++ b/lib/websocket/receiver.js
@@ -12,10 +12,6 @@ const { WebsocketFrameSend } = require('./frame')
 // Copyright (c) 2013 Arnout Kazemier and contributors
 // Copyright (c) 2016 Luigi Pinca and contributors
 
-// const channels = {}
-// channels.ping = diagnosticsChannel.channel('undici:websocket:ping')
-// channels.pong = diagnosticsChannel.channel('undici:websocket:pong')
-
 class ByteParser extends Writable {
   #buffers = []
   #byteOffset = 0
diff --git a/package.json b/package.json
index 17015f7b1b8..3d5f7ed20c5 100644
--- a/package.json
+++ b/package.json
@@ -80,9 +80,10 @@
     "test:node-fetch": "mocha --exit test/node-fetch",
     "test:fetch": "npm run build:node && borp --expose-gc --coverage -p \"test/fetch/*.js\" && borp --coverage -p \"test/webidl/*.js\"",
     "test:jest": "jest",
-    "test:tap": "tap test/*.js test/diagnostics-channel/*.js",
-    "test:node-test": "borp --coverage -p \"test/node-test/*.js\"",
-    "test:tdd": "tap test/*.js test/diagnostics-channel/*.js -w",
+    "test:tap": "tap test/*.js",
+    "test:node-test": "borp --coverage -p \"test/node-test/**/*.js\"",
+    "test:tdd": "tap test/*.js --coverage -w",
+    "test:tdd:node-test": "borp -p \"test/node-test/**/*.js\" -w",
     "test:typescript": "tsd && tsc --skipLibCheck test/imports/undici-import.ts",
     "test:websocket": "borp --coverage -p \"test/websocket/*.js\"",
     "test:wpt": "node test/wpt/start-fetch.mjs && node test/wpt/start-FileAPI.mjs && node test/wpt/start-mimesniff.mjs && node test/wpt/start-xhr.mjs && node test/wpt/start-websockets.mjs",
diff --git a/test/node-test/diagnostics-channel/connect-error.js b/test/node-test/diagnostics-channel/connect-error.js
index 35559fab86a..1cc255c8d46 100644
--- a/test/node-test/diagnostics-channel/connect-error.js
+++ b/test/node-test/diagnostics-channel/connect-error.js
@@ -23,7 +23,7 @@ test('Diagnostics channel - connect error', (t) => {
     _connector = connector
 
     assert.equal(typeof _connector, 'function')
-    assert.equal(Object.keys(connectParams).length, 6)
+    assert.equal(Object.keys(connectParams).length, 7)
 
     const { host, hostname, protocol, port, servername } = connectParams
 
@@ -35,7 +35,7 @@ test('Diagnostics channel - connect error', (t) => {
   })
 
   diagnosticsChannel.channel('undici:client:connectError').subscribe(({ error, connectParams, connector }) => {
-    assert.equal(Object.keys(connectParams).length, 6)
+    assert.equal(Object.keys(connectParams).length, 7)
     assert.equal(_connector, connector)
 
     const { host, hostname, protocol, port, servername } = connectParams
diff --git a/test/node-test/diagnostics-channel/error.js b/test/node-test/diagnostics-channel/error.js
index 2a737d70b33..9b320b59824 100644
--- a/test/node-test/diagnostics-channel/error.js
+++ b/test/node-test/diagnostics-channel/error.js
@@ -12,7 +12,7 @@ try {
   process.exit(0)
 }
 
-const { Client } = require('../..')
+const { Client } = require('../../..')
 const { createServer } = require('http')
 
 test('Diagnostics channel - error', (t) => {
diff --git a/test/node-test/diagnostics-channel/get.js b/test/node-test/diagnostics-channel/get.js
index e0feeb2fe56..a41df9d2563 100644
--- a/test/node-test/diagnostics-channel/get.js
+++ b/test/node-test/diagnostics-channel/get.js
@@ -12,7 +12,7 @@ try {
   process.exit(0)
 }
 
-const { Client } = require('../..')
+const { Client } = require('../../..')
 const { createServer } = require('http')
 
 test('Diagnostics channel - get', (t) => {
@@ -51,7 +51,7 @@ test('Diagnostics channel - get', (t) => {
     _connector = connector
 
     assert.equal(typeof _connector, 'function')
-    assert.equal(Object.keys(connectParams).length, 6)
+    assert.equal(Object.keys(connectParams).length, 7)
 
     const { host, hostname, protocol, port, servername } = connectParams
 
@@ -67,7 +67,7 @@ test('Diagnostics channel - get', (t) => {
     _socket = socket
 
     assert.equal(_connector, connector)
-    assert.equal(Object.keys(connectParams).length, 6)
+    assert.equal(Object.keys(connectParams).length, 7)
 
     const { host, hostname, protocol, port, servername } = connectParams
 
diff --git a/test/node-test/diagnostics-channel/post-stream.js b/test/node-test/diagnostics-channel/post-stream.js
index 3510e74993b..aa2792a2732 100644
--- a/test/node-test/diagnostics-channel/post-stream.js
+++ b/test/node-test/diagnostics-channel/post-stream.js
@@ -13,7 +13,7 @@ try {
   process.exit(0)
 }
 
-const { Client } = require('../..')
+const { Client } = require('../../..')
 const { createServer } = require('http')
 
 test('Diagnostics channel - post stream', (t) => {
@@ -53,7 +53,7 @@ test('Diagnostics channel - post stream', (t) => {
     _connector = connector
 
     assert.equal(typeof _connector, 'function')
-    assert.equal(Object.keys(connectParams).length, 6)
+    assert.equal(Object.keys(connectParams).length, 7)
 
     const { host, hostname, protocol, port, servername } = connectParams
 
@@ -68,7 +68,7 @@ test('Diagnostics channel - post stream', (t) => {
   diagnosticsChannel.channel('undici:client:connected').subscribe(({ connectParams, socket, connector }) => {
     _socket = socket
 
-    assert.equal(Object.keys(connectParams).length, 6)
+    assert.equal(Object.keys(connectParams).length, 7)
     assert.equal(_connector, connector)
 
     const { host, hostname, protocol, port, servername } = connectParams
diff --git a/test/node-test/diagnostics-channel/post.js b/test/node-test/diagnostics-channel/post.js
index 1f0475bd556..427853b66ea 100644
--- a/test/node-test/diagnostics-channel/post.js
+++ b/test/node-test/diagnostics-channel/post.js
@@ -12,7 +12,7 @@ try {
   process.exit(0)
 }
 
-const { Client } = require('../../..')
+const { Client } = require('../../../')
 const { createServer } = require('http')
 
 test('Diagnostics channel - post', (t) => {
@@ -51,7 +51,7 @@ test('Diagnostics channel - post', (t) => {
     _connector = connector
 
     assert.equal(typeof _connector, 'function')
-    assert.equal(Object.keys(connectParams).length, 6)
+    assert.equal(Object.keys(connectParams).length, 7)
 
     const { host, hostname, protocol, port, servername } = connectParams
 
@@ -66,7 +66,7 @@ test('Diagnostics channel - post', (t) => {
   diagnosticsChannel.channel('undici:client:connected').subscribe(({ connectParams, socket, connector }) => {
     _socket = socket
 
-    assert.equal(Object.keys(connectParams).length, 6)
+    assert.equal(Object.keys(connectParams).length, 7)
     assert.equal(_connector, connector)
 
     const { host, hostname, protocol, port, servername } = connectParams

From 4a1617470d7128d573f9572e5e24321904e7b55f Mon Sep 17 00:00:00 2001
From: Carlos Fuentes <me@metcoder.dev>
Date: Fri, 5 Jan 2024 12:12:42 +0100
Subject: [PATCH 06/10] refactor: use debuglog instead

---
 lib/core/diagnostics.js | 123 ++++++++++++++++++++++++----------------
 1 file changed, 73 insertions(+), 50 deletions(-)

diff --git a/lib/core/diagnostics.js b/lib/core/diagnostics.js
index 16c3c8e1dc2..c6bad94f050 100644
--- a/lib/core/diagnostics.js
+++ b/lib/core/diagnostics.js
@@ -1,5 +1,9 @@
 const diagnosticsChannel = require('diagnostics_channel')
+const util = require('util')
 
+const undiciDebugLog = util.debuglog('undici')
+const fetchDebuglog = util.debuglog('fetch')
+const websocketDebuglog = util.debuglog('websocket')
 let isClientSet = false
 const channels = {
   // Client
@@ -21,16 +25,19 @@ const channels = {
   pong: diagnosticsChannel.channel('undici:websocket:pong')
 }
 
-if (process.env.NODE_DEBUG?.match(/(fetch|undici)/) != null) {
+if (undiciDebugLog.enabled || fetchDebuglog.enabled) {
+  const debuglog = fetchDebuglog.enabled ? fetchDebuglog : undiciDebugLog
+
   // Track all Client events
   diagnosticsChannel.channel('undici:client:beforeConnect').subscribe(evt => {
     const {
       connectParams: { version, protocol, port, host }
     } = evt
-    console.log(
-      `HTTP:undici ${process.pid}: connecting to ${host}${
-        port ? `:${port}` : ''
-      } using ${protocol}${version}`
+    debuglog(
+      'connecting to %s using %s%s',
+      `${host}${port ? `:${port}` : ''}`,
+      protocol,
+      version
     )
   })
 
@@ -38,10 +45,11 @@ if (process.env.NODE_DEBUG?.match(/(fetch|undici)/) != null) {
     const {
       connectParams: { version, protocol, port, host }
     } = evt
-    console.log(
-      `HTTP:undici ${process.pid}: connected to ${host}${
-        port ? `:${port}` : ''
-      } using ${protocol}${version}`
+    debuglog(
+      'connected to %s using %s%s',
+      `${host}${port ? `:${port}` : ''}`,
+      protocol,
+      version
     )
   })
 
@@ -50,10 +58,12 @@ if (process.env.NODE_DEBUG?.match(/(fetch|undici)/) != null) {
       connectParams: { version, protocol, port, host },
       error
     } = evt
-    console.log(
-      `HTTP:undici ${process.pid}: connection to ${host}${
-        port ? `:${port}` : ''
-      } using ${protocol}${version} errored - ${error.message}`
+    debuglog(
+      'connection to %s using %s%s errored - %s',
+      `${host}${port ? `:${port}` : ''}`,
+      protocol,
+      version,
+      error.message
     )
   })
 
@@ -61,9 +71,7 @@ if (process.env.NODE_DEBUG?.match(/(fetch|undici)/) != null) {
     const {
       request: { method, path, origin }
     } = evt
-    console.log(
-      `HTTP:undici ${process.pid}: sending request to ${method} ${origin}/${path}`
-    )
+    debuglog('sending request to %s %s/%s', method, origin, path)
   })
 
   // Track Request events
@@ -72,8 +80,12 @@ if (process.env.NODE_DEBUG?.match(/(fetch|undici)/) != null) {
       request: { method, path, origin },
       response: { statusCode }
     } = evt
-    console.log(
-      `HTTP:undici ${process.pid}: received response ${method} ${origin}/${path} - HTTP ${statusCode}`
+    debuglog(
+      'received response to %s %s/%s - HTTP %d',
+      method,
+      origin,
+      path,
+      statusCode
     )
   })
 
@@ -81,9 +93,7 @@ if (process.env.NODE_DEBUG?.match(/(fetch|undici)/) != null) {
     const {
       request: { method, path, origin }
     } = evt
-    console.log(
-      `HTTP:undici ${process.pid}: trailers received from ${method} ${origin}/${path}`
-    )
+    debuglog('trailers received from %s %s/%s', method, origin, path)
   })
 
   diagnosticsChannel.channel('undici:request:error').subscribe(evt => {
@@ -91,24 +101,31 @@ if (process.env.NODE_DEBUG?.match(/(fetch|undici)/) != null) {
       request: { method, path, origin },
       error
     } = evt
-    console.log(
-      `HTTP:undici ${process.pid}: request errored ${method} ${origin}/${path} - ${error.message}`
+    debuglog(
+      'request to %s %s/%s errored - %s',
+      method,
+      origin,
+      path,
+      error.message
     )
   })
 
   isClientSet = true
 }
 
-if (process.env.NODE_DEBUG?.match(/websocket/) != null) {
+if (websocketDebuglog.enabled) {
   if (!isClientSet) {
+    const debuglog = undiciDebugLog.enabled ? undiciDebugLog : websocketDebuglog
     diagnosticsChannel.channel('undici:client:beforeConnect').subscribe(evt => {
       const {
         connectParams: { version, protocol, port, host }
       } = evt
-      console.log(
-        `HTTP:undici ${process.pid}: connecting to ${host}${
-          port ? `:${port}` : ''
-        } using ${protocol}${version}`
+      debuglog(
+        'connecting to %s%s using %s%s',
+        host,
+        port ? `:${port}` : '',
+        protocol,
+        version
       )
     })
 
@@ -116,10 +133,12 @@ if (process.env.NODE_DEBUG?.match(/websocket/) != null) {
       const {
         connectParams: { version, protocol, port, host }
       } = evt
-      console.log(
-        `HTTP:undici ${process.pid}: connected to ${host}${
-          port ? `:${port}` : ''
-        } using ${protocol}${version}`
+      debuglog(
+        'connected to %s%s using %s%s',
+        host,
+        port ? `:${port}` : '',
+        protocol,
+        version
       )
     })
 
@@ -128,10 +147,13 @@ if (process.env.NODE_DEBUG?.match(/websocket/) != null) {
         connectParams: { version, protocol, port, host },
         error
       } = evt
-      console.log(
-        `HTTP:undici ${process.pid}: connection to ${host}${
-          port ? `:${port}` : ''
-        } using ${protocol}${version} errored - ${error.message}`
+      debuglog(
+        'connection to %s%s using %s%s errored - %s',
+        host,
+        port ? `:${port}` : '',
+        protocol,
+        version,
+        error.message
       )
     })
 
@@ -139,9 +161,7 @@ if (process.env.NODE_DEBUG?.match(/websocket/) != null) {
       const {
         request: { method, path, origin }
       } = evt
-      console.log(
-        `HTTP:undici ${process.pid}: sending request to ${method} ${origin}/${path}`
-      )
+      debuglog('sending request to %s %s/%s', method, origin, path)
     })
   }
 
@@ -152,32 +172,35 @@ if (process.env.NODE_DEBUG?.match(/websocket/) != null) {
       protocol,
       extensions
     } = evt
-    console.log(
-      `WebSocket:undici ${process.pid}: connection opened ${address}${
-        port ? `:${port}` : ''
-      } using ${protocol}-${extensions}`
+    websocketDebuglog(
+      'connection opened %s%s using %s-%s',
+      address,
+      port ? `:${port}` : '',
+      protocol,
+      extensions
     )
   })
 
   diagnosticsChannel.channel('undici:websocket:close').subscribe(evt => {
     const { websocket, code, reason } = evt
-    console.log(
-      `WebSocket:undici ${process.pid}: closed connection to ${websocket.url} - ${code} ${reason}`
+    websocketDebuglog(
+      'closed connection to %s - %s %s',
+      websocket.url,
+      code,
+      reason
     )
   })
 
   diagnosticsChannel.channel('undici:websocket:socket_error').subscribe(err => {
-    console.log(
-      `WebSocket:undici ${process.pid}: connection errored - ${err.message}`
-    )
+    websocketDebuglog('connection errored - %s', err.message)
   })
 
   diagnosticsChannel.channel('undici:websocket:ping').subscribe(evt => {
-    console.log(`WebSocket:undici ${process.pid}: ping received`)
+    websocketDebuglog('ping received')
   })
 
   diagnosticsChannel.channel('undici:websocket:pong').subscribe(evt => {
-    console.log(`WebSocket:undici ${process.pid}: pong received`)
+    websocketDebuglog('pong received')
   })
 }
 

From 3c60f7ab270678a015febacc4be1465a57e1f0fc Mon Sep 17 00:00:00 2001
From: Carlos Fuentes <me@metcoder.dev>
Date: Fri, 5 Jan 2024 12:33:52 +0100
Subject: [PATCH 07/10] docs: add documentation

---
 docs/api/Debug.md              | 62 ++++++++++++++++++++++++++++++++++
 docs/api/DiagnosticsChannel.md |  6 ++--
 lib/core/diagnostics.js        | 12 ++-----
 3 files changed, 67 insertions(+), 13 deletions(-)
 create mode 100644 docs/api/Debug.md

diff --git a/docs/api/Debug.md b/docs/api/Debug.md
new file mode 100644
index 00000000000..1a1794c0ad9
--- /dev/null
+++ b/docs/api/Debug.md
@@ -0,0 +1,62 @@
+# Debug
+
+Undici (and subsenquently `fetch` and `websocket`) exposes a debug statement that can be enabled by setting `NODE_DEBUG` within the environment.
+
+The flags availabile are:
+
+## `undici`
+
+This flag enables debug statements for the core undici library.
+
+```sh
+NODE_DEBUG=undici node script.js
+
+UNDICI 16241: connecting to nodejs.org using https:h1
+UNDICI 16241: connecting to nodejs.org using https:h1
+UNDICI 16241: connected to nodejs.org using https:h1
+UNDICI 16241: sending request to GET https://nodejs.org//
+UNDICI 16241: received response to GET https://nodejs.org// - HTTP 307
+UNDICI 16241: connecting to nodejs.org using https:h1
+UNDICI 16241: trailers received from GET https://nodejs.org//
+UNDICI 16241: connected to nodejs.org using https:h1
+UNDICI 16241: sending request to GET https://nodejs.org//en
+UNDICI 16241: received response to GET https://nodejs.org//en - HTTP 200
+UNDICI 16241: trailers received from GET https://nodejs.org//en
+```
+
+## `fetch`
+
+This flag enables debug statements for the `fetch` API.
+
+> **Note**: statements are pretty similar to the ones in the `undici` flag, but scoped to `fetch`
+
+```sh
+NODE_DEBUG=fetch node script.js
+
+FETCH 16241: connecting to nodejs.org using https:h1
+FETCH 16241: connecting to nodejs.org using https:h1
+FETCH 16241: connected to nodejs.org using https:h1
+FETCH 16241: sending request to GET https://nodejs.org//
+FETCH 16241: received response to GET https://nodejs.org// - HTTP 307
+FETCH 16241: connecting to nodejs.org using https:h1
+FETCH 16241: trailers received from GET https://nodejs.org//
+FETCH 16241: connected to nodejs.org using https:h1
+FETCH 16241: sending request to GET https://nodejs.org//en
+FETCH 16241: received response to GET https://nodejs.org//en - HTTP 200
+FETCH 16241: trailers received from GET https://nodejs.org//en
+```
+
+## `websocket`
+
+This flag enables debug statements for the `Websocket` API.
+
+> **Note**: statements can overlap with `UNDICI` ones if `undici` or `fetch` flag has been enabled as well.
+
+```sh
+NODE_DEBUG=fetch node script.js
+
+WEBSOCKET 18309: connecting to echo.websocket.org using https:h1
+WEBSOCKET 18309: connected to echo.websocket.org using https:h1
+WEBSOCKET 18309: sending request to GET https://echo.websocket.org//
+WEBSOCKET 18309: connection opened <ip_address>
+```
\ No newline at end of file
diff --git a/docs/api/DiagnosticsChannel.md b/docs/api/DiagnosticsChannel.md
index 0aa0b9a0783..6e6ad6e4de8 100644
--- a/docs/api/DiagnosticsChannel.md
+++ b/docs/api/DiagnosticsChannel.md
@@ -105,7 +105,7 @@ You can not assume that this event is related to any specific request.
 import diagnosticsChannel from 'diagnostics_channel'
 
 diagnosticsChannel.channel('undici:client:beforeConnect').subscribe(({ connectParams, connector }) => {
-  // const { host, hostname, protocol, port, servername } = connectParams
+  // const { host, hostname, protocol, port, servername, version } = connectParams
   // connector is a function that creates the socket
 })
 ```
@@ -118,7 +118,7 @@ This message is published after a connection is established.
 import diagnosticsChannel from 'diagnostics_channel'
 
 diagnosticsChannel.channel('undici:client:connected').subscribe(({ socket, connectParams, connector }) => {
-  // const { host, hostname, protocol, port, servername } = connectParams
+  // const { host, hostname, protocol, port, servername, version } = connectParams
  // connector is a function that creates the socket
 })
 ```
@@ -131,7 +131,7 @@ This message is published if it did not succeed to create new connection
 import diagnosticsChannel from 'diagnostics_channel'
 
 diagnosticsChannel.channel('undici:client:connectError').subscribe(({ error, socket, connectParams, connector }) => {
-  // const { host, hostname, protocol, port, servername } = connectParams
+  // const { host, hostname, protocol, port, servername, version } = connectParams
   // connector is a function that creates the socket
   console.log(`Connect failed with ${error.message}`)
 })
diff --git a/lib/core/diagnostics.js b/lib/core/diagnostics.js
index c6bad94f050..fd9b3db4195 100644
--- a/lib/core/diagnostics.js
+++ b/lib/core/diagnostics.js
@@ -168,17 +168,9 @@ if (websocketDebuglog.enabled) {
   // Track all WebSocket events
   diagnosticsChannel.channel('undici:websocket:open').subscribe(evt => {
     const {
-      address: { address, port },
-      protocol,
-      extensions
+      address: { address, port }
     } = evt
-    websocketDebuglog(
-      'connection opened %s%s using %s-%s',
-      address,
-      port ? `:${port}` : '',
-      protocol,
-      extensions
-    )
+    websocketDebuglog('connection opened %s%s', address, port ? `:${port}` : '')
   })
 
   diagnosticsChannel.channel('undici:websocket:close').subscribe(evt => {

From e13d7a15a6b4c08898610222641d3e6557a5d4b0 Mon Sep 17 00:00:00 2001
From: Carlos Fuentes <me@metcoder.dev>
Date: Sun, 7 Jan 2024 11:28:54 +0100
Subject: [PATCH 08/10] fix: code review

---
 docsify/sidebar.md      | 1 +
 lib/core/diagnostics.js | 1 +
 2 files changed, 2 insertions(+)

diff --git a/docsify/sidebar.md b/docsify/sidebar.md
index 35d5c614ce5..d5bd69a219c 100644
--- a/docsify/sidebar.md
+++ b/docsify/sidebar.md
@@ -18,6 +18,7 @@
   * [MockErrors](/docs/api/MockErrors.md "Undici API - MockErrors")
   * [API Lifecycle](/docs/api/api-lifecycle.md "Undici API - Lifecycle")
   * [Diagnostics Channel Support](/docs/api/DiagnosticsChannel.md "Diagnostics Channel Support")
+  * [Debug](/docs/api/Debug.md.md "Undici API - Debugging Undici")
   * [WebSocket](/docs/api/WebSocket.md "Undici API - WebSocket")
   * [MIME Type Parsing](/docs/api/ContentType.md "Undici API - MIME Type Parsing")
   * [CacheStorage](/docs/api/CacheStorage.md "Undici API - CacheStorage")
diff --git a/lib/core/diagnostics.js b/lib/core/diagnostics.js
index fd9b3db4195..e76f73a8c3a 100644
--- a/lib/core/diagnostics.js
+++ b/lib/core/diagnostics.js
@@ -1,3 +1,4 @@
+'use strict'
 const diagnosticsChannel = require('diagnostics_channel')
 const util = require('util')
 

From 8515e0b468154f38855dcac1ddbcc87fde68589a Mon Sep 17 00:00:00 2001
From: Carlos Fuentes <me@metcoder.dev>
Date: Sun, 7 Jan 2024 11:29:13 +0100
Subject: [PATCH 09/10] test: add testing coverage

---
 test/debug.js              | 94 ++++++++++++++++++++++++++++++++++++++
 test/fixtures/fetch.js     |  6 +++
 test/fixtures/undici.js    |  6 +++
 test/fixtures/websocket.js | 16 +++++++
 4 files changed, 122 insertions(+)
 create mode 100644 test/debug.js
 create mode 100644 test/fixtures/fetch.js
 create mode 100644 test/fixtures/undici.js
 create mode 100644 test/fixtures/websocket.js

diff --git a/test/debug.js b/test/debug.js
new file mode 100644
index 00000000000..dd07a87289f
--- /dev/null
+++ b/test/debug.js
@@ -0,0 +1,94 @@
+'use strict'
+
+const { test } = require('node:test')
+const { spawn } = require('node:child_process')
+const { tspl } = require('@matteo.collina/tspl')
+const { join } = require('node:path')
+
+test('debug#websocket', async t => {
+  const assert = tspl(t, { plan: 5 })
+  const child = spawn(
+    process.execPath,
+    [join(__dirname, 'fixtures/websocket.js')],
+    {
+      env: {
+        NODE_DEBUG: 'websocket'
+      }
+    }
+  )
+
+  t.after(() => {
+    child.kill()
+  })
+
+  child.stderr.setEncoding('utf8')
+
+  for await (const chunk of child.stderr) {
+    if (chunk.includes('[UNDICI-WS] Warning')) {
+      continue
+    }
+
+    assert.match(
+      chunk,
+      /(WEBSOCKET [0-9]+:) (connecting to|connected to|sending request|connection opened|closed connection)/
+    )
+  }
+})
+
+test('debug#fetch', async t => {
+  // Due to Node.js webpage redirect
+  const assert = tspl(t, { plan: 10 })
+  const child = spawn(
+    process.execPath,
+    [join(__dirname, 'fixtures/fetch.js')],
+    {
+      env: {
+        NODE_DEBUG: 'fetch'
+      }
+    }
+  )
+
+  t.after(() => {
+    child.kill()
+  })
+
+  child.stderr.setEncoding('utf8')
+
+  for await (const chunk of child.stderr) {
+    if (chunk.includes('[UNDICI-WS] Warning')) {
+      continue
+    }
+
+    assert.match(
+      chunk,
+      /(FETCH [0-9]+:) (connecting to|connected to|sending request|received response|trailers received|request to)/
+    )
+  }
+})
+
+test('debug#undici', async t => {
+  // Due to Node.js webpage redirect
+  const assert = tspl(t, { plan: 10 })
+  const child = spawn(
+    process.execPath,
+    [join(__dirname, 'fixtures/undici.js')],
+    {
+      env: {
+        NODE_DEBUG: 'undici'
+      }
+    }
+  )
+
+  t.after(() => {
+    child.kill()
+  })
+
+  child.stderr.setEncoding('utf8')
+
+  for await (const chunk of child.stderr) {
+    assert.match(
+      chunk,
+      /(UNDICI [0-9]+:) (connecting to|connected to|sending request|received response|trailers received|request to)/
+    )
+  }
+})
diff --git a/test/fixtures/fetch.js b/test/fixtures/fetch.js
new file mode 100644
index 00000000000..ef2ea7b6e98
--- /dev/null
+++ b/test/fixtures/fetch.js
@@ -0,0 +1,6 @@
+const { fetch } = require('../..')
+
+fetch('https://nodejs.org').then(
+  res => res.body.cancel(),
+  () => {}
+)
diff --git a/test/fixtures/undici.js b/test/fixtures/undici.js
new file mode 100644
index 00000000000..51aac6bf943
--- /dev/null
+++ b/test/fixtures/undici.js
@@ -0,0 +1,6 @@
+const { request } = require('../..')
+
+request('https://nodejs.org', { maxRedirections: 1 }).then(
+  res => res.body.dump(),
+  () => {}
+)
diff --git a/test/fixtures/websocket.js b/test/fixtures/websocket.js
new file mode 100644
index 00000000000..ca8c83513fc
--- /dev/null
+++ b/test/fixtures/websocket.js
@@ -0,0 +1,16 @@
+const { WebSocketServer } = require('ws')
+const { WebSocket } = require('../..')
+
+const server = new WebSocketServer({ port: 0 })
+
+server.on('connection', ws => {
+  ws.close(1000, 'goodbye')
+})
+
+const { port } = server.address()
+
+const ws = new WebSocket(`ws://localhost:${port}`, 'chat')
+
+ws.addEventListener('close', () => {
+  server.close()
+})

From b4c8883362d3ffd08d02c11b409df3086a31ed32 Mon Sep 17 00:00:00 2001
From: Carlos Fuentes <me@metcoder.dev>
Date: Sun, 7 Jan 2024 11:30:05 +0100
Subject: [PATCH 10/10] refactor: remove leftover

---
 test/debug.js | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/test/debug.js b/test/debug.js
index dd07a87289f..61930e75843 100644
--- a/test/debug.js
+++ b/test/debug.js
@@ -55,10 +55,6 @@ test('debug#fetch', async t => {
   child.stderr.setEncoding('utf8')
 
   for await (const chunk of child.stderr) {
-    if (chunk.includes('[UNDICI-WS] Warning')) {
-      continue
-    }
-
     assert.match(
       chunk,
       /(FETCH [0-9]+:) (connecting to|connected to|sending request|received response|trailers received|request to)/