Fix another issue with TypeScript default exports

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+### Fixed
+
+- Fix another issue with TypeScript default exports. See [#418](https://github.com/helmetjs/helmet/pull/418)
+
 ## 6.1.3 - 2023-04-10
 
 ### Fixed

build/build-package.ts

@@ -164,6 +164,9 @@ async function buildTypes({
   await bundle.write({
     file: outputPath,
     format: "esm",
+    // Despite this being an ES module, some TypeScript setups require this.
+    // (This doesn't remove the `export default` from the final file.)
+    outro: "export = helmet",
   });
 
   await bundle.close();

test/project-setups/typescript-nodenext-commonjs/package.json

@@ -0,0 +1,7 @@
+{
+  "private": true,
+  "type": "commonjs",
+  "scripts": {
+    "helmet:test": "ts-node-esm --compilerOptions '{\"module\": \"nodenext\", \"moduleResolution\": \"nodenext\"}' test.ts"
+  }
+}

test/project-setups/typescript-nodenext/package.json → test/project-setups/typescript-nodenext-esm/package.json

@@ -1,5 +1,6 @@
 {
   "private": true,
+  "type": "module",
   "scripts": {
     "helmet:test": "ts-node-esm --compilerOptions '{\"module\": \"nodenext\", \"moduleResolution\": \"nodenext\"}' test.ts"
   }

test/project-setups/typescript-nodenext-esm/test.ts

@@ -0,0 +1,42 @@
+import type { IncomingMessage, ServerResponse } from "http";
+import connect from "connect";
+import supertest from "supertest";
+import helmet, { frameguard } from "helmet";
+
+const handler = (_: IncomingMessage, res: ServerResponse) =>
+  res.end("Hello world");
+
+async function testTopLevel() {
+  const app = connect().use(helmet()).use(handler);
+  await supertest(app)
+    .get("/")
+    .expect(200, "Hello world")
+    .expect("x-download-options", "noopen");
+}
+
+async function testImportedMiddleware() {
+  const app = connect().use(frameguard()).use(handler);
+  await supertest(app)
+    .get("/")
+    .expect(200, "Hello world")
+    .expect("x-frame-options", "SAMEORIGIN");
+}
+
+async function testAttachedMiddleware() {
+  const app = connect().use(helmet.frameguard()).use(handler);
+  await supertest(app)
+    .get("/")
+    .expect(200, "Hello world")
+    .expect("x-frame-options", "SAMEORIGIN");
+}
+
+async function main() {
+  await testTopLevel();
+  await testImportedMiddleware();
+  await testAttachedMiddleware();
+}
+
+main().catch((err) => {
+  console.error(err);
+  process.exit(1);
+});