Underlying HttpServer is of type any

[royhadad]

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

app.listen() and app.getHttpServer() return the underlying HttpServer, but regarding types - the returned type is any.
Is there a way we can improve this type?
Currently, I'm doing this, which feels unsafe:

Minimum reproduction code

https://codesandbox.io/s/ecstatic-sanderson-xpxxfv

Steps to reproduce

1. go to the codesandbox link
2. hover over the server const.
3. see it's of type any

Expected behavior

I expect server to have a safer type, perhaps { Server } from 'https'?
maybe something else? Open for suggestions

Package

• I don't know. Or some 3rd-party package
• @nestjs/common
• @nestjs/core
• @nestjs/microservices
• @nestjs/platform-express
• @nestjs/platform-fastify
• @nestjs/platform-socket.io
• @nestjs/platform-ws
• @nestjs/testing
• @nestjs/websockets
• Other (see below)

Other package

No response

NestJS version

8.0.6

Packages versions

    "@nestjs/core": "8.0.6",

Node.js version

16.14.0

In which operating systems have you tested?

• macOS
• Windows
• Linux

Other

Relevant source code block:

nest/packages/common/interfaces/nest-application.interface.ts

Line 57 in 21bd8c3

listen(port: number | string, callback?: () => void): Promise<any>;

[micalevisk]

Let's use the express adapter as an example:

nest/packages/platform-express/adapters/express-adapter.ts

Lines 186 to 193 in 21bd8c3

	if (isHttpsEnabled) {
	this.httpServer = https.createServer(
	options.httpsOptions,
	this.getInstance(),
	);
	return;
	}
	this.httpServer = http.createServer(this.getInstance());

nest/packages/platform-express/adapters/express-adapter.ts

Lines 118 to 119 in 21bd8c3

	public listen(port: any, ...args: any[]) {
	return this.httpServer.listen(port, ...args);

as you can see above, we can't define the right return type statically for the return of listen because it could be either
import { Server } from 'https' or
import { Server } from 'http'
which is defined at runtime.

---

What we could do is narrow down that a bit. That method could then have the following return type instead of any:
HttpServer | HttpsServer
What do you think?

[micalevisk]

nvm lol

I just found that the Server is the same regardless of the http module being used:

• nodejs docs on server.listen of https: https://nodejs.org/api/https.html#serverlisten
• nodejs docs on server.listen of http: https://nodejs.org/api/http.html#serverlisten

both of them points to server.listen method from net module, which return net.Server.

So we could replace that any with net.Server since
server instanceof net.Server === true.

[kamilmysliwiec]

Let's track this here #10481

[royhadad]

Great! do we want to make the same adjustment in other places as well? (e.g. fastify)

[micalevisk]

I thought that the listen on fastify adapter always returns undefined due to the types defined below

nest/packages/platform-fastify/adapters/fastify-adapter.ts

Lines 222 to 228 in 60d286d

	public listen(port: string | number, callback?: () => void): void;
	public listen(
	port: string | number,
	hostname: string,
	callback?: () => void,
	): void;
	public listen(port: string | number, ...args: any[]): void {

but I just tested it and it returns the same Server instance. I'll update that too then.

[micalevisk]

I'm getting Type 'void' is not assignable to type 'Server' because instance.listen returns void even tho await app.listen(port, () => {}) returns Server 🤔 I might be missing something

nest/packages/platform-fastify/adapters/fastify-adapter.ts

Line 237 in 60d286d

return this.instance.listen(options, callback);

[royhadad]

Well, as you've stated yourself, the actual object is different from the type definition, it makes sense that you get a type error. Using the as keyword could potentially solve this, I guess.

[micalevisk]

yeah, I need to figure out why the type of this.instance.listen() is void. Feel free to investigate that please