Express route HMR with Webpack - express

Question

I'm trying to get HMR to work on the server-side with an express app and I'm seeing some odd behavior. My simple test project;
index.ts
let httpListener: Server = null;
let AppServer = require('./AppServer').default;
const port = Config.serverPort;
if (process.env.NODE_ENV === 'dev') {
if ((module as any).hot) {
(module as any).hot.addDisposeHandler((data: any) => {
httpListener.close();
AppServer = require('./AppServer').default;
});
console.log('index.ts', (module as any).hot.dependencies);
(module as any).hot.accept((err: any) => {
console.log('HMR Error', err);
});
}
}
httpListener = AppServer.app.listen(port, (error: Error) => {
if (error) {
console.error(error);
} else {
console.info(`Listening on port ${port}.`);
}
});
AppServer.ts
class AppServer {
public app: express.Application = express();
constructor() {
this.app.use('/api', (new ApiRouter()).router);
}
}
export default new AppServer();
and ApiRouter.ts
export class ApiRouter {
public router: express.Router = express.Router();
constructor() {
this.router.use('/auth', (new AuthRouter()).router);
this.router.get('/', (req, res) => {
res.json({success: true});
});
}
}
Webpack bundles correctly, and HMR reports modules being updated. If I change some code in index.ts, those changes take effect. However, when I flip {success: true} to {success: false}, I see HMR update;
[HMR] Updated modules:
[HMR] - ./src/server/AppServer.ts
[HMR] - ./src/server/index.ts
[HMR] - ./src/server/api/ApiRouter.ts
but when I hit the endpoint, I get back {success: true}. So despite HMR seemingly doing the right thing, the code isn't being changed at run-time. I suspect I'm missing something fundamental about how module.hot.accept works here, but I can not figure out where I'm going wrong.
Has anyone gotten this to work correctly?