fix: handle cases of chunked middleware (#2574)

* test: make middleware fixture produce chunked middleware

* fix: handle cases of chunked middleware

Author: pieh

src/build/functions/edge.ts

@@ -125,7 +125,7 @@ const copyHandlerDependencies = async (
     const entrypoint = await readFile(join(srcDir, file), 'utf8')
     parts.push(`;// Concatenated file: ${file} \n`, entrypoint)
   }
-  const exports = `export default _ENTRIES["middleware_${name}"].default;`
+  const exports = `const middlewareEntryKey = Object.keys(_ENTRIES).find(entryKey => entryKey.startsWith("middleware_${name}")); export default _ENTRIES[middlewareEntryKey].default;`
   await mkdir(dirname(join(destDir, `server/${name}.js`)), { recursive: true })
 
   await writeFile(join(destDir, `server/${name}.js`), [...parts, exports].join('\n'))

tests/fixtures/middleware/next.config.js

@@ -4,6 +4,13 @@ const nextConfig = {
   eslint: {
     ignoreDuringBuilds: true,
   },
+  webpack: (config) => {
+    // this is a trigger to generate multiple `.next/server/middleware-[hash].js` files instead of
+    // single `.next/server/middleware.js` file
+    config.optimization.splitChunks.maxSize = 100_000
+
+    return config
+  },
 }
 
 module.exports = nextConfig