test(sample): add required file test

ensure sample 29 controller throws an error when a file is required but none is given

Author: thiagomini

sample/29-file-upload/e2e/app/app.e2e-spec.ts

@@ -51,6 +51,13 @@ describe('E2E FileTest', () => {
       .expect(400);
   });
 
+  it('should throw when file is required but no file is uploaded', async () => {
+    return request(app.getHttpServer())
+      .post('/file/fail-validation')
+      .send()
+      .expect(400);
+  });
+
   it('should allow for optional file uploads with validation enabled (fixes #10017)', () => {
     return request(app.getHttpServer())
       .post('/file/pass-validation')