1auth.service.ts

import { Injectable } from '@angular/core';

@Injectable()
export class AuthService {

}

2auth.module.ts

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';

import { AuthService } from './auth.service';

@NgModule({
  imports: [
    CommonModule,
  ],
  declarations: [LoginComponent],
  providers: [AuthService]
})
export class AuthModule { }