fix: improve error message when handler not found from worker (#117)

Author: AriPerkkio

src/entry/process.ts

@@ -69,7 +69,9 @@ async function onMessage(message: IncomingMessage & { source: 'port' }) {
   try {
     const handler = await getHandler(filename, name)
     if (handler === null) {
-      throw new Error(`No handler function exported from ${filename}`)
+      throw new Error(
+        `No handler function "${name}" exported from "${filename}"`
+      )
     }
     const result = await handler(task)
     response = {

src/entry/worker.ts

@@ -100,7 +100,9 @@ function onMessage(
     try {
       const handler = await getHandler(filename, name)
       if (handler === null) {
-        throw new Error(`No handler function exported from ${filename}`)
+        throw new Error(
+          `No handler function "${name}" exported from "${filename}"`
+        )
       }
       let result = await handler(task)
       if (isMovable(result)) {

test/uncaught-exception-from-handler.test.ts

@@ -1,4 +1,4 @@
-import { dirname, resolve } from 'node:path'
+import { dirname, resolve, sep } from 'node:path'
 import { Tinypool } from 'tinypool'
 import { fileURLToPath } from 'node:url'
 import { once } from 'node:events'
@@ -67,3 +67,23 @@ test('using parentPort is treated as an error', async () => {
       `)
   ).rejects.toThrow(/Unexpected message on Worker: 'some message'/)
 })
+
+test('no named handler found from worker', async () => {
+  const pool = new Tinypool({
+    filename: resolve(__dirname, 'fixtures/eval.js'),
+  })
+
+  let errorMessage = 'Worker did not throw error'
+
+  try {
+    await pool.run('', { name: 'someHandler' })
+  } catch (error) {
+    errorMessage = error instanceof Error ? error.message : String(error)
+  }
+
+  expect(
+    errorMessage.replace(process.cwd(), '<process-cwd>').replaceAll(sep, '/')
+  ).toMatchInlineSnapshot(
+    `"No handler function "someHandler" exported from "<process-cwd>/test/fixtures/eval.js""`
+  )
+})