[Express] [Type Update] Use generics for Response (#42662)

* use-generics-for-express-response-type: Use generics for Response in express

* use-generics-for-express-response-type: fixing ghost-storage-base-tests

types/express/express-tests.ts

@@ -164,6 +164,18 @@ namespace express_tests {
     // Params cannot be a custom type that does not conform to constraint
     router.get<{ foo: number }>('/:foo', () => {}); // $ExpectError
 
+    // Response will default to any type
+    router.get("/", (req: Request, res: express.Response) => {
+        res.json({});
+    });
+
+    // Response will be of Type provided
+    router.get("/", (req: Request, res: express.Response<string>) => {
+        res.json();
+        res.json(1); // $ExpectError
+        res.send(1); // $ExpectError
+    });
+
     app.use((req, res, next) => {
         // hacky trick, router is just a handler
         router(req, res, next);

types/express/index.d.ts

@@ -2,6 +2,7 @@
 // Project: http://expressjs.com
 // Definitions by: Boris Yankov <https://github.com/borisyankov>
 //                 China Medical University Hospital <https://github.com/CMUH>
+//                 Puneet Arora <https://github.com/puneetar>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.3
 
@@ -99,7 +100,7 @@ declare namespace e {
     interface Request<P extends core.Params = core.ParamsDictionary> extends core.Request<P> { }
     interface RequestHandler<P extends core.Params = core.ParamsDictionary> extends core.RequestHandler<P> { }
     interface RequestParamHandler extends core.RequestParamHandler { }
-    export interface Response extends core.Response { }
+    export interface Response<ResBody = any> extends core.Response<ResBody> { }
     interface Router extends core.Router { }
     interface Send extends core.Send { }
 }

types/ghost-storage-base/ghost-storage-base-tests.ts

@@ -41,5 +41,5 @@ storage.getSanitizedFileName('IMAGE.jpg'); // $ExpectType string
 
 storage.exists('tmp/123456.jpg', '/'); // $ExpectType Promise<boolean>
 storage.save(image, '/'); // $ExpectType Promise<string>
-storage.serve(); // $ExpectType (req: Request<ParamsDictionary>, res: Response, next: NextFunction) => void
+storage.serve(); // $ExpectType (req: Request<ParamsDictionary>, res: Response<any>, next: NextFunction) => void
 storage.delete('tmp/123456.jpg', '/'); // $ExpectType Promise<boolean>