feat: Send server identification

src/server/ExpressHttpServer.ts

@@ -1,6 +1,6 @@
 import { Server } from 'http';
 import cors from 'cors';
-import express from 'express';
+import express, { Express } from 'express';
 import { HttpHandler } from './HttpHandler';
 
 export class ExpressHttpServer {
@@ -12,14 +12,26 @@ export class ExpressHttpServer {
 
   public listen(port?: number): Server {
     const app = express();
+    this.setup(app);
+    return app.listen(port);
+  }
 
+  protected setup(app: Express): void {
+    // Set up server identification
+    app.use((request, response, done): void => {
+      response.setHeader('X-Powered-By', 'Community Solid Server');
+      done();
+    });
+
+    // Set up Cross-Origin Resource Sharing (CORS)
     app.use(cors({
       // Based on https://github.com/solid/solid-spec/blob/master/recommendations-server.md#cors---cross-origin-resource-sharing
       // By default origin is always '*', this forces it to be the origin header if there is one
       origin: (origin, callback): void => callback(null, (origin ?? '*') as any),
       methods: [ 'GET', 'HEAD', 'OPTIONS', 'POST', 'PUT', 'PATCH', 'DELETE' ],
     }));
 
+    // Delegate to the main handler
     app.use(async(request, response, done): Promise<void> => {
       try {
         await this.handler.handleSafe({ request, response });
@@ -31,6 +43,5 @@ export class ExpressHttpServer {
         done();
       }
     });
-    return app.listen(port);
   }
 }

test/unit/server/ExpressHttpServer.test.ts

@@ -42,6 +42,13 @@ describe('ExpressHttpServer', (): void => {
     server.close();
   });
 
+  it('sends server identification in the X-Powered-By header.', async(): Promise<void> => {
+    const res = await request(server).get('/');
+    expect(res.header).toEqual(expect.objectContaining({
+      'x-powered-by': 'Community Solid Server',
+    }));
+  });
+
   it('returns CORS headers for an OPTIONS request.', async(): Promise<void> => {
     const res = await request(server)
       .options('/')