fix(build): preserve websocket export in bun adapter output (#337)

* fix(build): preserve websocket export in bun adapter output

* ci: apply automated fixes

* chore(changeset): add patch release note for bun websocket export fix

* format

* add `// eslint-disable-next-line quotes`

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Yusuke Wada <yusuke@kamawada.com>

Author: 3 people

.changeset/clever-mails-warn.md

@@ -0,0 +1,6 @@
+---
+'@hono/vite-build': patch
+---
+
+Fix Bun adapter build output to preserve an entry's `websocket` handler in the generated default export.
+This prevents Bun runtime WebSocket upgrade failures when apps export `{ fetch, websocket }`.

packages/build/src/adapter/bun/index.ts

@@ -1,12 +1,38 @@
 import type { Plugin } from 'vite'
 import type { BuildOptions } from '../../base.js'
-import buildPlugin from '../../base.js'
+import buildPlugin, { defaultOptions as baseDefaultOptions } from '../../base.js'
 import { serveStaticHook } from '../../entry/serve-static.js'
 
 export type BunBuildOptions = {
   staticRoot?: string | undefined
 } & BuildOptions
 
+export const defaultOptions: BunBuildOptions = {
+  ...baseDefaultOptions,
+  entryContentAfterHooks: [
+    () => `
+      let websocket
+      for (const [, app] of Object.entries(modules)) {
+        if (
+          app &&
+          typeof app === 'object' &&
+          'websocket' in app &&
+          app.websocket !== undefined
+        ) {
+          if (websocket !== undefined) {
+            throw new Error(
+              \`Handler "websocket" is defined in multiple entry files. Please ensure each handler is defined only once.\`
+            )
+          }
+          websocket = app.websocket
+        }
+      }
+    `,
+  ],
+  entryContentDefaultExportHook: (appName) =>
+    `export default websocket !== undefined ? { fetch: ${appName}.fetch.bind(${appName}), websocket } : ${appName}`,
+}
+
 const bunBuildPlugin = (pluginOptions?: BunBuildOptions): Plugin => {
   return {
     ...buildPlugin({
@@ -25,6 +51,11 @@ const bunBuildPlugin = (pluginOptions?: BunBuildOptions): Plugin => {
         ],
       },
       ...pluginOptions,
+      entryContentAfterHooks:
+        pluginOptions?.entryContentAfterHooks ?? defaultOptions.entryContentAfterHooks,
+      entryContentDefaultExportHook:
+        pluginOptions?.entryContentDefaultExportHook ??
+        defaultOptions.entryContentDefaultExportHook,
     }),
     name: '@hono/vite-build/bun',
   }

packages/build/test/adapter.test.ts

@@ -45,6 +45,26 @@ describe('Build Plugin with Bun Adapter', () => {
     // eslint-disable-next-line quotes
     expect(outputJsClientJs).toContain("console.log('foo')")
   })
+
+  it('Should preserve websocket from entry default export in generated bundle', async () => {
+    const outputFile = `${testDir}/dist/index.js`
+
+    await build({
+      root: testDir,
+      plugins: [
+        bunBuildPlugin({
+          entry: './src/server-fetch-with-websocket.ts',
+          minify: false,
+        }),
+      ],
+    })
+
+    expect(existsSync(outputFile)).toBe(true)
+
+    const output = readFileSync(outputFile, 'utf-8')
+    expect(output).toContain('websocket')
+    expect(output).toMatch(/fetch:\s*mainApp\.fetch\.bind\(mainApp\)/)
+  })
 })
 
 describe('Build Plugin with Netlify Functions Adapter', () => {

packages/build/test/mocks/app-static-files/src/server-fetch-with-websocket.ts

@@ -0,0 +1,8 @@
+import app from './server'
+
+export default {
+  fetch: app.fetch,
+  websocket: {
+    open: () => {},
+  },
+}