feat: emit request and response event on app

src/application.ts

@@ -187,10 +187,16 @@ export class Application extends Emitter {
    * @private
    */
   protected async handleRequest(ctx: ContextDelegation, fnMiddleware: (ctx: ContextDelegation) => Promise<void>) {
+    this.emit('request', ctx);
     const res = ctx.res;
     res.statusCode = 404;
     const onerror = (err: any) => ctx.onerror(err);
-    onFinished(res, onerror);
+    onFinished(res, (err: any) => {
+      if (err) {
+        onerror(err);
+      }
+      this.emit('response', ctx);
+    });
     try {
       await fnMiddleware(ctx);
       return this._respond(ctx);

test/application/index.test.ts

@@ -4,7 +4,6 @@ import CreateError from 'http-errors';
 import Koa from '../../src/index.js';
 
 describe('app', () => {
-  // ignore test on Node.js v18
   it('should handle socket errors', done => {
     const app = new Koa();
 
@@ -25,6 +24,36 @@ describe('app', () => {
       });
   });
 
+  it('should emit request and response event', done => {
+    const app = new Koa();
+    let requestCount = 0;
+    let responseCount = 0;
+    app.on('request', ctx => {
+      assert.equal(ctx.url, '/');
+      requestCount++;
+    });
+    app.on('response', ctx => {
+      assert.equal(ctx.url, '/');
+      assert.equal(ctx.status, 404);
+      responseCount++;
+      if (responseCount === 2) {
+        assert.equal(requestCount, 2);
+        done();
+      }
+    });
+
+    request(app.callback())
+      .get('/')
+      .end(() => {
+        // empty
+      });
+    request(app.callback())
+      .get('/')
+      .end(() => {
+        // empty
+      });
+  });
+
   it('should not .writeHead when !socket.writable', done => {
     const app = new Koa();