fix: Correctly assign response headers from httpGraphQLResponse (#34)

Response headers from Apollo Server weren't being assigned to the
final response object.

Author: trevor-scheer

src/__tests__/integration.test.ts

@@ -0,0 +1,67 @@
+import { ApolloServer, type ApolloServerOptions, type BaseContext } from '@apollo/server';
+import {
+  defineIntegrationTestSuite,
+  type CreateServerForIntegrationTestsOptions,
+} from '@apollo/server-integration-testsuite';
+import type { Server } from 'http';
+import type { AddressInfo } from 'net';
+import { format } from 'url';
+import { startServerAndCreateGoogleCloudFunctionsHandler } from '..';
+
+const { getTestServer } = require('@google-cloud/functions-framework/testing');
+
+describe('cloud functions handler', () => {
+  defineIntegrationTestSuite(
+    async function (
+      serverOptions: ApolloServerOptions<BaseContext>,
+      testOptions?: CreateServerForIntegrationTestsOptions,
+    ) {
+      const apolloServer = new ApolloServer({
+        ...serverOptions,
+      });
+
+      startServerAndCreateGoogleCloudFunctionsHandler(apolloServer, {
+        functionTarget: 'apolloServer',
+        context: testOptions?.context,
+      });
+
+      const testServer = getTestServer('apolloServer');
+      await new Promise<void>((resolve) => {
+        testServer.listen({ port: 0 }, resolve);
+      });
+
+      return {
+        server: apolloServer,
+        url: urlForHttpServer(testServer),
+        async extraCleanup() {
+          await new Promise<void>((resolve) => {
+            testServer.close(() => resolve());
+          });
+        },
+      };
+    },
+    {
+      serverIsStartedInBackground: true,
+      noIncrementalDelivery: true,
+    },
+  );
+});
+
+// Stolen from apollo server integration tests
+export function urlForHttpServer(httpServer: Server): string {
+  const { address, port } = httpServer.address() as AddressInfo;
+
+  // Convert IPs which mean "any address" (IPv4 or IPv6) into localhost
+  // corresponding loopback ip. Note that the url field we're setting is
+  // primarily for consumption by our test suite. If this heuristic is wrong for
+  // your use case, explicitly specify a frontend host (in the `host` option
+  // when listening).
+  const hostname = address === '' || address === '::' ? 'localhost' : address;
+
+  return format({
+    protocol: 'http',
+    hostname,
+    port,
+    pathname: '/',
+  });
+}

src/index.ts

@@ -10,7 +10,7 @@ interface Options<Context extends BaseContext> {
   functionTarget: string;
 }
 
-type GoogleCloudApiHandler = (req: Request, res: Response) => Promise<unknown> | unknown;
+export type GoogleCloudApiHandler = (req: Request, res: Response) => Promise<unknown> | unknown;
 
 const defaultContext: ContextFunction<[], any> = async () => ({});
 
@@ -60,6 +60,10 @@ export function startServerAndCreateGoogleCloudFunctionsHandler<Context extends
       },
     });
 
+    for (const [key, value] of httpGraphQLResponse.headers) {
+      res.setHeader(key, value);
+    }
+
     res.statusCode = httpGraphQLResponse.status || 200;
 
     if (httpGraphQLResponse.body.kind === 'complete') {