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Angular 5 and 4 Unit Test - Karma and Jasmine!

Introduction to Angular Test- Driven Development | Unit/e2e Testing Guides‎
ü  What is Unit Test in Angular?
ü  What Is Integration Testing in Angular?
ü  How to Test a components inputs as well as its outputs?
ü  How to Interact with a components view?

Types of Test in Angular 4/2 and Angular
The all great developer knows his/her testing tools uses. Understanding your tools for testing is essential before diving into writing tests.

The Testing is depends on your project requirements and the project cost. The types of Testing looks like -
1.     Unit Test
2.     Integration Test
3.     End to End (e2e) Test

Unit TestWhat is Unit Test in Angular? The Unit Test is used to testing a single function, single components in Isolation. This is very fast.

In this Test, we are not able to say that everything is all right in the application. Just for a single Unit or function assure that working fine.

Integration Testing – What Is Integration Testing in Angular? The Integration Testing is used to testing a component with templates and this testing containing more time as per comparison Unit Test.

End to End Test (e2e) – What is End-to-End Testing in Angular? The End to End Testing is used to testing the entire application looks like -
1.     All User Interactions
2.     All Service Calls
3.     Authentication/Authorization of app
4.     Everything of App

This is the actual testing of your append it is fast action.
Unit testing and Integrations testing will do as fake calls but e2e testing is done with your actual Services and APIs calls.


Recommended Unit Testing Tools – Angular 4/2 and Angular
·       Karma
·       Jasmine and
·       QUnit

Test Function – After installing everything as per your project requirements, CREATE your project.
The following Steps –
ü  ng new YourTestProject
ü  ng install
ü  ng serve/ng test

Note – If you are going to development then type ng server command and if you want to test your project, you should type ng test command.  After type ng test command and press inter. It’s taking some time to installing everything in your project for test.

Test functions
1.     describe – Test suit (just a function)
2.     it  - The spec or test
3.     expect -  Expected outcome.

Triple Rule of Testing –
1.     Arrange - Create and Initialize the Components
2.     Act -  Invoke the Methods/Functions of Components
3.     Assert - Assert the expected outcome/behaviour

Best Practices - The quick list of best practices.
ü  Use beforeEach() to Initialize the context for your tests.
ü  Make sure the string descriptions you put in describe () and it () make sense as output
ü  Use after () and afterEach () to clean-up your tests if there is any state that may bleed over.
ü  If any one test is over 15 lines of code, you may need to refactor the test

A Simple Example as –
import { TestBed, async } from '@angular/core/testing';
import { AppComponent } from './app.component';

//describe – Test suit (just a function)
describe('AppComponent', () => {
  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [AppComponent]
    }).compileComponents();
  }));

 // it - The spec or test
 it('should have hello property', function() {
  const fixture = TestBed.createComponent(AppComponent);
  const app = fixture.debugElement.componentInstance;

   //expect – This Is For expected outcome.
   expect(app.hello).toBe('Hello, Anil!');
 });
});


Example 1
app.component.ts –
import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'app';
}


app.component.spec.ts –
import { TestBed, async } from '@angular/core/testing';
import { AppComponent } from './app.component';

describe('AppComponent', () => {
  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [
        AppComponent
      ],
    }).compileComponents();
  }));

  it('should create the app', async(() => {
    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.debugElement.componentInstance;
   
    expect(app).toBeTruthy();
  }));

  it(`should have as title 'app'`, async(() => {
    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.debugElement.componentInstance;

    expect(app.title).toEqual('app');
  }));

  it('should render title in a h1 tag', async(() => {
    const fixture = TestBed.createComponent(AppComponent);
    fixture.detectChanges();
    const compiled = fixture.debugElement.nativeElement;

    expect(compiled.querySelector('h1').textContent).toContain('Welcome to app!');
  }));
});


app.component.html –
<div style="text-align:center">
  <h1>  Welcome to {{title}}! </h1>
</div>
<h2>Here are some links to help you start: </h2>
<ul>
  <li>
    <h2><a target="_blank" rel="noopener" href="https://code-sample.com/">Tour of Examples</a></h2>
  </li>
  <li>
    <h2><a target="_blank" rel="noopener" href="https://code-sample.com/">CLI Documentation</a></h2>
  </li>
</ul>


Example 2 – Login Testing
login.component.ts-
import { Component, OnInit, EventEmitter,Input, Output, ViewEncapsulation } from '@angular/core';

@Component({
  selector: 'app-login',
  templateUrl: './login.component.html',
  styleUrls: ['./login.component.css'],
  encapsulation: ViewEncapsulation.None
})
export class LoginComponent implements OnInit {

  @Output() loggedIn = new EventEmitter<User>();
  @Input() enabled = true;

  constructor() { }

  ngOnInit() {  }

  login(email, password) {
    if (email && password) {
       this.loggedIn.emit(new User(email, password));
    }
   
    console.log(`Login ${email} ${password}`);
  }
}

export class User {
  constructor(public email: string, public password: string) {
  }
}

login.component.spec.ts –
import { async, ComponentFixture, TestBed } from '@angular/core/testing';
import {Component, DebugElement} from "@angular/core";
import {LoginComponent, User } from './login.component';
import {By} from "@angular/platform-browser";

describe('LoginComponent', () => {
  let component: LoginComponent;
  let fixture: ComponentFixture<LoginComponent>;
  let submitElement: DebugElement;
  let loginElement: DebugElement;
  let passwordElement: DebugElement;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [LoginComponent]
    })
    .compileComponents();
  }));

  beforeEach(() => {
    fixture = TestBed.createComponent(LoginComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();

    submitElement = fixture.debugElement.query(By.css('button'));
    loginElement = fixture.debugElement.query(By.css('input[type=email]'));
    passwordElement = fixture.debugElement.query(By.css('input[type=password]'));
  });

  it('Setting enabled to false disabled the submit button', () => {
    component.enabled = false;
    fixture.detectChanges();

    //Expected outcome
    expect(submitElement.nativeElement.disabled).toBeTruthy();
  });

  it('Setting enabled to true enables the submit button', () => {
    component.enabled = true;
    fixture.detectChanges();

    //Expected outcome
    expect(submitElement.nativeElement.disabled).toBeFalsy();
  });

  it('Entering email and password emits loggedIn event', () => {
    let user: User;

    loginElement.nativeElement.value = "anil.singh@code-sample.com";
    passwordElement.nativeElement.value = "$ystem!1356";

    // Subscribe to the Observable and store the user in a local variable.
    component.loggedIn.subscribe((value) => user = value);

    // This sync emits the event and the subscribe callback gets executed above
    submitElement.triggerEventHandler('click', null);

    //Expected outcome
    expect(user.email).toBe("anil.singh@code-sample.com");
    expect(user.password).toBe("$ystem!1356");
  });

});


login.component.html –
<form>
  <label>Email</label>
  <input type="email" #email>
  <label>Password</label>
  <input type="password" #password>
  <button type="button"
          (click)="login(email.value, password.value)"
          [disabled]="!enabled">Login
  </button>
</form>



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