Unable to test a component with a service - unit-testing

Question

After reading this guide I've decided to test my simple login page which contains just 2 input boxes and a submit button. The component then uses a LoginService to pass these data to backend.
( Also note that I'm new to Unit testing as such, so I'm not sure if this is a good approach as how to test such component. )
For starters, I only wanted to check, if the initial value of #username input element is empty. But I couldn't even make the spec to work due to the below reported issues:
Chrome 55.0.2883 (Windows 7 0.0.0) LoginComponent Username field should be empty FAILED
Failed: Unexpected value 'Http' imported by the module 'DynamicTestModule'
Error: Unexpected value 'Http' imported by the module 'DynamicTestModule'
TypeError: Cannot read property 'detectChanges' of undefined
Chrome 55.0.2883 (Windows 7 0.0.0): Executed 4 of 4 (1 FAILED) (0 secs / 0.348 secs)
When I tried deleting the Http module, I got this error :
Chrome 55.0.2883 (Windows 7 0.0.0) LoginComponent Username field should be empty FAILED
Error: DI Error
Error: Uncaught (in promise): Error: No provider for Http!
TypeError: Cannot read property 'detectChanges' of undefined
Chrome 55.0.2883 (Windows 7 0.0.0): Executed 4 of 4 (1 FAILED) (0 secs / 0.456 secs)
login.component.html
<div class="login jumbotron center-block">
<h1>Login</h1>
<form (ngSubmit)="onSubmit($event)" #loginForm="ngForm">
<div class="form-group">
<label for="username">Username</label>
<input type="text" class="form-control" [(ngModel)]="model.username" name="username"
placeholder="Username" #username="ngModel" required>
<div [hidden]="username.valid || username.pristine" class="alert alert-danger"> Username is required </div>
</div>
<div class="form-group">
<label for="password">Password</label>
<input type="password" class="form-control" [(ngModel)]="model.password" name="password" placeholder="Password" #password="ngModel" required>
<div [hidden]="password.valid || password.pristine" class="alert alert-danger"> Password is required </div>
</div>
<button type="submit" class="btn btn-default" [disabled]="!loginForm.form.valid" >Submit</button>
<a [routerLink]="['/signup']">Click here to Signup</a>
</form>
</div>
login.component.ts
import { Component } from '#angular/core';
import { Router } from '#angular/router';
import { LoginService } from '../services/login.service';
import { User } from '../extensions/user.class';
#Component({
moduleId: module.id,
selector: 'login',
templateUrl: '../templates/login.component.html',
styleUrls: [ '../styles/login.component.css' ],
providers: [ LoginService ]
})
export class LoginComponent {
private submitted = false;
private model = new User();
constructor(
private router: Router,
private loginService: LoginService
) {}
public onSubmit(event: any): void {
event.preventDefault();
if ( ! this.submitted ) {
this.submitted = true;
if ( this.model.username && this.model.password ) {
this.loginService.login(this.model).then( (token) => {
localStorage.setItem('id_token', token.id);
this.router.navigate(['home']);
}).catch( (error) => this.onLoginFailed(error) );
} else {
console.warn('No username or password provided');
}
}
}
private onLoginFailed( error: any ): void {
//// errors are already handled in login-service ////
console.error(error);
this.submitted = false; /// reset form submit funcitonality ///
}
public signup(event: any): void {
event.preventDefault();
this.router.navigate(['signup']);
}
}
login.component.spec.ts
import { async } from '#angular/core/testing';
import { FormsModule } from '#angular/forms';
import { RouterTestingModule } from '#angular/router/testing';
import { Component } from '#angular/core';
import { Location } from '#angular/common';
import { LoginComponent } from './login.component';
import { LoginService } from '../services/login.service';
import { Http } from '#angular/http';
import { User } from '../extensions/user.class';
#Component({
template: ''
})
class DummyComponent{}
class LoginServiceStub {
login( user: User ){
return true;
}
}
describe('LoginComponent', () => {
let comp: LoginComponent;
let fixture: ComponentFixture<LoginComponent>;
let de: DebugElement;
let el: HTMLElement;
let location: Location;
// async beforeEach
beforeEach( async(() => {
TestBed.configureTestingModule({
declarations: [ LoginComponent, DummyComponent ], // declare the test component
providers: [
{ provide: LoginService, useClass: LoginServiceStub }
],
imports: [
FormsModule ,
RouterTestingModule.withRoutes([
{ path: 'singup', component: DummyComponent }
])
]
}).compileComponents() // compile template and css
.then( () => {
fixture = TestBed.createComponent(LoginComponent);
comp = fixture.componentInstance; // LoginComponent test instance
de = fixture.debugElement.query(By.css('input[name="username"]'));
el = de.nativeElement;
});
}));
it('Username field should be empty', () => {
fixture.detectChanges();
expect(el.textContent).toContain('');
});
});

Answer 1

The problem is that the LoginService is declared at the component level
#Component({
providers: [ LoginService ]
})
This will supersede any same service declared at the module level, which is where you declare the mock in the test. There are a couple things you can do:
Don't declare the service at the component level. If there is not good reason to scope it to the component, then just declare it at the #NgModule.providers and make it a singleton.
Override the #Component.providers in the test.
TestBed.configureTestingModule({})
TestBed.overrideComponent(LoginComponent, {
set: {
providers: [
{ provide: LoginService, useClass: LoginServiceStub }
]
}
});

Answer 2

Alexus,
Have you tried importing the Http module into your test component and adding it to the "providers" array? I think you would have to specify all of your dependencies in this case. I'm assuming your LoginService is requiring {Http} as a provision, but your test component does not register {Http} so it can't find an instance to use.
EDIT:
TestBed.configureTestingModule({
declarations: [ LoginComponent, DummyComponent ], // declare the test component
providers: [
{ provide: LoginService, useClass: LoginServiceStub },
Http,
],
imports: [
FormsModule ,
RouterTestingModule.withRoutes([
{ path: 'singup', component: DummyComponent }
])
]
DOUBLE EDIT!:
In addition, you'll probably want to mock out the Http module, as you won't actually want to send a request during your unit test. "MockBackend" from #angular/http/testing is sufficient for this -- in this case, you would want to use the "provide" syntax you uses with the Login Service to provide an Http module that uses the MockBackend to generate responses.