Self-injection causes the app to get stuck in the initializing process without error

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

When an Injectable tries to inject itself in the constructor, the initializing process hangs without showing any error.

import { Injectable } from '@nestjs/common';

@Injectable()
export class AppService {
  constructor(private readonly appService: AppService) {}
  getHello(): string {
    return 'Hello World!';
  }
}

App’s logs:

[12:49:52 PM] File change detected. Starting incremental compilation...
api_1       | 
api_1       | [12:49:53 PM] Found 0 errors. Watching for file changes.
api_1       | 
api_1       | For help, see: https://nodejs.org/en/docs/inspector
api_1       | [Nest] 182  - 01/11/2022, 12:49:54 PM     LOG [NestFactory] Starting Nest application...
api_1       | [Nest] 182  - 01/11/2022, 12:49:54 PM     LOG [InstanceLoader] PrismaModule dependencies initialized +119ms
api_1       | [Nest] 182  - 01/11/2022, 12:49:54 PM     LOG [InstanceLoader] UsersModule dependencies initialized +2ms

Minimum reproduction code

https://codesandbox.io/s/friendly-lalande-ni9oq

Steps to reproduce

No response

Expected behavior

Nest should throw an error describing that the provider cannot inject itself.

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

8.1.9

Packages versions

{
  "name": "server",
  "version": "0.0.1",
  "description": "",
  "author": "",
  "private": true,
  "license": "UNLICENSED",
  "scripts": {
    "prebuild": "rimraf dist",
    "build": "nest build",
    "format": "prettier --write \"src/**/*.ts\" \"test/**/*.ts\"",
    "start": "nest start",
    "start:dev": "nest start --watch",
    "start:debug": "nest start --debug 0.0.0.0:9229 --watch",
    "start:prod": "node dist/main",
    "lint": "eslint \"{src,apps,libs,test}/**/*.ts\" --fix",
    "test": "jest",
    "test:watch": "jest --watch",
    "test:cov": "jest --coverage",
    "test:debug": "node --inspect-brk -r tsconfig-paths/register -r ts-node/register node_modules/.bin/jest --runInBand",
    "test:e2e": "jest --config ./test/jest-e2e.json"
  },
  "dependencies": {
    "@nestjs/common": "^8.0.0",
    "@nestjs/core": "^8.0.0",
    "@nestjs/mapped-types": "*",
    "@nestjs/platform-express": "^8.0.0",
    "@prisma/client": "^3.7.0",
    "class-transformer": "^0.5.1",
    "class-validator": "^0.13.2",
    "reflect-metadata": "^0.1.13",
    "rimraf": "^3.0.2",
    "rxjs": "^7.2.0"
  },
  "devDependencies": {
    "@nestjs/cli": "^8.0.0",
    "@nestjs/schematics": "^8.0.0",
    "@nestjs/testing": "^8.0.0",
    "@types/express": "^4.17.13",
    "@types/jest": "27.0.2",
    "@types/node": "^16.0.0",
    "@types/supertest": "^2.0.11",
    "@typescript-eslint/eslint-plugin": "^5.0.0",
    "@typescript-eslint/parser": "^5.0.0",
    "eslint": "^8.0.1",
    "eslint-config-prettier": "^8.3.0",
    "eslint-plugin-prettier": "^4.0.0",
    "jest": "^27.2.5",
    "prettier": "^2.3.2",
    "prisma": "^3.7.0",
    "source-map-support": "^0.5.20",
    "supertest": "^6.1.3",
    "ts-jest": "^27.0.3",
    "ts-loader": "^9.2.3",
    "ts-node": "^10.0.0",
    "tsconfig-paths": "^3.10.1",
    "typescript": "^4.3.5"
  },
  "jest": {
    "moduleFileExtensions": [
      "js",
      "json",
      "ts"
    ],
    "rootDir": "src",
    "testRegex": ".*\\.spec\\.ts$",
    "transform": {
      "^.+\\.(t|j)s$": "ts-jest"
    },
    "collectCoverageFrom": [
      "**/*.(t|j)s"
    ],
    "coverageDirectory": "../coverage",
    "testEnvironment": "node"
  }
}

Node.js version

v16.13.1

In which operating systems have you tested?

• macOS
• Windows
• Linux

Other

No response

[jmcdo29]

I was able to replicate this. I’ll try to figure out where the exit is happening so that it can be properly reported

[micalevisk]

for reference: using another token but the same class will lead to this issue as well.

class AppService {
  constructor(@Inject('Foo') appService: any) {}
}

@Module({
  providers: [
   { provide: 'Foo', useClass: AppService }
  ],
})
class AppModule {}