Angular 2 unit test case is not working for services with external module configuration - unit-testing

Question

If I create a module with services using #Inject method is not working with Angular 2 Testbed Unit test cases. It is throwing No Provider for AppService Error.
app.module.ts
import { BrowserModule } from '#angular/platform-browser';
import { NgModule } from '#angular/core';
import { FormsModule } from '#angular/forms';
import { HttpModule } from '#angular/http';
import { AppComponent } from './app.component';
import { AppService } from './app.service';
#NgModule({
declarations: [
AppComponent
],
imports: [
BrowserModule,
FormsModule,
HttpModule
],
providers: [
{provide:'AppService',useClass:AppService}
],
bootstrap: [AppComponent]
})
export class AppModule { }
app.component.ts
import { Component, Inject } from '#angular/core';
#Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
title = 'app works!';
constructor(#Inject('AppService') private appService) {}
getName() {
this.title = this.appService.getName();
}
setName(name) {
this.appService.setName(name);
}
}
app.service.ts
import { Injectable } from '#angular/core';
#Injectable()
export class AppService {
private name = 'dummy';
public getName() {
return this.name;
}
public setName(name) {
console.log("ser", name);
this.name = name;
}
}
app.component.spec.ts
import { Injectable} from '#angular/core';
import { TestBed, async, inject } from '#angular/core/testing';
import { AppComponent } from './app.component';
import { FormsModule } from '#angular/forms';
import { AppService } from './app.service';
describe('AppComponent', () => {
let fixture, comp, appService;
beforeEach(() => {
TestBed.configureTestingModule({
imports: [FormsModule],
declarations: [
AppComponent
],
providers: [AppService]
}).compileComponents();
fixture = TestBed.createComponent(AppComponent);
comp = fixture.debugElement.componentInstance;
appService = fixture.debugElement.injector.get(AppService);
});
it('should create the app', async(() => {
expect(comp).toBeTruthy();
}));
});

Answer 1

try adding providers: [AppService] in #Component in app.component.ts as below
#Component({
providers: [AppService],
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})