feat: Added transformer injection

README.md

@@ -1,12 +1,13 @@
 # Tracing Hooks
 
-This repository contains a ESM loader for injecting tracing channel hooks into Node.js modules. It also has a patch for Module to be used to patch CJS modules.
+This repository contains a ESM loader for injecting tracing channel hooks into
+Node.js modules. It also has a patch for Module to be used to patch CJS modules.
 
 ## Usage
 
 Note: the module loading hooks API in Node.js has changed as of
 v26. To support all active Node.js versions with
-forward-compatibility, create a combined loader as an ESM module.
+forward-compatibility, create a combined loader as an ES Module (ESM).
 
 This can be done for any CommonJS _or_ ES Module application, but
 the loader itself must use ESM.
@@ -138,4 +139,4 @@ On this path, diagnostics for ES modules are posted from the loader thread and
 therefore arrive asynchronously, some time after the module was transformed;
 diagnostics for CommonJS modules come from the `_compile` patch and are emitted
 synchronously as before. The port does not keep the process alive, so
-diagnostics still in flight when the process exits are dropped.
+diagnostics still in flight when the process exits are dropped.

hook-sync.mjs

@@ -1 +1,7 @@
-export { initializeSync as initialize, loadSync as load, resolveSync as resolve, setDiagnosticsHook, createDiagnosticsPort } from './hook.mjs'
+export {
+  initializeSync as initialize,
+  loadSync as load,
+  resolveSync as resolve,
+  setDiagnosticsHook,
+  createDiagnosticsPort
+} from './hook.mjs'

hook.mjs

@@ -1,12 +1,15 @@
 'use strict'
-import createDebug from 'debug'
-import { create } from '@apm-js-collab/code-transformer'
-import parse from 'module-details-from-path'
+
+import { readFile } from 'node:fs/promises'
+import { readFileSync } from 'node:fs'
 import { fileURLToPath } from 'node:url'
 import { MessageChannel } from 'node:worker_threads'
-import getPackageVersion from './lib/get-package-version.js'
+import { create as defaultCreate } from '@apm-js-collab/code-transformer'
+import createDebug from 'debug'
+import parse from 'module-details-from-path'
 import { setDiagnosticsHook, emitDiagnostics } from './lib/diagnostics.js'
-import { readFileSync } from 'node:fs'
+import getPackageVersion from './lib/get-package-version.js'
+
 const debug = createDebug('@apm-js-collab/tracing-hooks:esm-hook')
 let transformers = null
 let packages = null
@@ -34,10 +37,10 @@ export function createDiagnosticsPort() {
   return port2
 }
 
-export async function initialize(data = {}) {
-  return initializeSync(data)
+export async function initialize(data = {}, { create = defaultCreate } = {}) {
+  return initializeSync(data, { create })
 }
-export function initializeSync(data = {}) {
+export function initializeSync(data = {}, { create = defaultCreate } = {}) {
   const instrumentations = data?.instrumentations || []
   instrumentator = create(instrumentations)
   packages = new Set(instrumentations.map(i => i.module.name))
@@ -152,4 +155,4 @@ export function loadResult(url, result) {
   }
 
   return result
-}
+}

index.js

@@ -1,5 +1,5 @@
 'use strict'
-const { create } = require('@apm-js-collab/code-transformer')
+const { create: defaultCreate } = require('@apm-js-collab/code-transformer')
 const Module = require('node:module')
 const parse = require('module-details-from-path')
 const { pathToFileURL } = require('node:url')
@@ -8,7 +8,7 @@ const { emitDiagnostics } = require('./lib/diagnostics')
 const debug = require('debug')('@apm-js-collab/tracing-hooks:module-patch')
 
 class ModulePatch {
-  constructor({ instrumentations = [] } = {}) {
+  constructor({ instrumentations = [], create = defaultCreate } = {}) {
     this.packages = new Set(instrumentations.map(i => i.module.name))
     this.instrumentator = create(instrumentations)
     this.compile = Module.prototype._compile