I’m running into a very troubling issue with NestJS and dependency injection.

Here is my NestJS Controller:

import { Controller, Get } from '@nestjs/common'
import { TestService } from './TestService.service'

@Controller()
export class TestController {
  constructor(private testService: TestService) {}

  @Get('join')
  join() {
    this.service.foo()
    return 'success'
  }
}

Here is my NestJS Service:

import { Injectable } from '@nestjs/common'

@Injectable()
export class TestService {
  foo() {
    console.log('foo')
  }
}

Here is my AppModule:

@Module({
  providers: [
    TestService,
  ],
  controllers: [
    TestController,
  ],
})
export class AppModule {}

Calling the above route throws an error:

TypeError: Cannot read properties of undefined (reading 'foo')

If I annotate the controller with property injection like so:

import { Controller, Get, Inject } from '@nestjs/common'
import { TestService } from './TestService.service'

@Controller()
export class TestController {
  @Inject(TestService) // <----- HERE
  constructor(private testService: TestService) {}

  @Get('join')
  join() {
    this.service.foo()
    return 'success'
  }
}

Then the call is a success. It would seem that without property-based injection, Nest DI isn’t registering my service.

Any ideas what could be wrong here?

NestJS deps:

"@nestjs/common": "^10.3.8",
"@nestjs/core": "^10.3.7",
"@nestjs/platform-express": "^10.3.7",