feature: improve error handling when starting server fails (#261)

* feature: improve error handling when starting server fails

* update code

* feature: add getFirstEvent function

* lint

* lint

* fix

* fix

* test

* test

* test

* lint

* lint

packages/preview-process/src/parts/WaitForServerToBeReady/WaitForServerToBeReady.ts

@@ -1,7 +1,14 @@
 import type { WebViewServer } from '../WebViewServerTypes/WebViewServerTypes.ts'
+import * as GetFirstEvent from '../GetFirstEvent/GetFirstEvent.ts'
 
 export const waitForServerToBeReady = async (server: WebViewServer, port: string): Promise<void> => {
-  const { resolve, promise } = Promise.withResolvers<void>()
-  server.listen(port, resolve)
-  await promise
+  const responsePromise = GetFirstEvent.getFirstEvent(server as any, {
+    error: 1,
+    listening: 2,
+  })
+  server.listen(port, () => {})
+  const { type, event } = await responsePromise
+  if (type === 1) {
+    throw new Error(`Server error: ${event}`)
+  }
 }

packages/preview-process/test/WaitForServerToBeReady.test.ts

@@ -1,16 +1,49 @@
-import { expect, jest, test } from '@jest/globals'
+import { expect, test } from '@jest/globals'
+import { EventEmitter } from 'node:events'
+import type { WebViewServer } from '../src/parts/WebViewServerTypes/WebViewServerTypes.ts'
 import * as WaitForServerToBeReady from '../src/parts/WaitForServerToBeReady/WaitForServerToBeReady.ts'
 
-test('waitForServerToBeReady', async () => {
-  const mockServer = {
-    listen: jest.fn((port, callback) => {
-      // @ts-ignore
+class MockServer extends EventEmitter implements WebViewServer {
+  handler = undefined
+  listening = false
+
+  setHandler(handler: any): void {
+    this.handler = handler
+  }
+
+  listen(port: string, callback: () => void): void {
+    process.nextTick(() => {
+      this.listening = true
+      this.emit('listening')
       callback()
-    }),
+    })
   }
+  isListening(): boolean {
+    return this.listening
+  }
+}
+
+test('waitForServerToBeReady - success', async () => {
+  const server = new MockServer()
+  const port = '3000'
+  await WaitForServerToBeReady.waitForServerToBeReady(server, port)
+  expect(server.listening).toBe(true)
+})
+
+test('waitForServerToBeReady - handles EADDRINUSE error', async () => {
+  const server = new MockServer()
+  const port = '3000'
+  process.nextTick(() => {
+    server.emit('error', new Error('EADDRINUSE'))
+  })
+  await expect(WaitForServerToBeReady.waitForServerToBeReady(server, port)).rejects.toThrow('EADDRINUSE')
+})
+
+test('waitForServerToBeReady - handles other errors', async () => {
+  const server = new MockServer()
   const port = '3000'
-  // @ts-ignore
-  await WaitForServerToBeReady.waitForServerToBeReady(mockServer, port)
-  expect(mockServer.listen).toHaveBeenCalledTimes(1)
-  expect(mockServer.listen).toHaveBeenCalledWith(port, expect.any(Function))
+  process.nextTick(() => {
+    server.emit('error', new Error('Some other error'))
+  })
+  await expect(WaitForServerToBeReady.waitForServerToBeReady(server, port)).rejects.toThrow('Some other error')
 })

packages/test-integration/test/PreviewProcessPortConflict.test.ts

@@ -2,7 +2,7 @@ import { expect, test } from '@jest/globals'
 import getPort from 'get-port'
 import { createPreviewProcess } from '../src/parts/CreatePreviewProcess/CreatePreviewProcess.js'
 
-test.skip('preview process - handles port already in use', async () => {
+test('preview process - handles port already in use', async () => {
   const previewProcess1 = createPreviewProcess()
   const previewProcess2 = createPreviewProcess()
   const id1 = 1
@@ -13,9 +13,8 @@ test.skip('preview process - handles port already in use', async () => {
   await previewProcess1.invoke('WebViewServer.start', id1, port)
 
   await previewProcess2.invoke('WebViewServer.create', id2)
-  // TODO improve error message
   await expect(previewProcess2.invoke('WebViewServer.start', id2, port)).rejects.toThrow(
-    "Failed to start webview server: TypeError: Cannot read properties of undefined (reading 'server')",
+    `Failed to start webview server: Server error: Error: listen EADDRINUSE: address already in use :::${port}`,
   )
 
   previewProcess1[Symbol.dispose]()