TestBed configuration in Angular - Mini Project: Build & Apply

Angular TestBed Configuration

📖 Scenario: You are writing tests for a simple Angular component that displays a greeting message. To test it properly, you need to set up Angular's TestBed configuration.

🎯 Goal: Set up the Angular TestBed configuration for a component called GreetingComponent and write a basic test to check if the component is created successfully.

📋 What You'll Learn

Create a TestBed configuration with GreetingComponent declared

Compile the components in the TestBed

Create a fixture and component instance for GreetingComponent

Write a test to check if the component instance is created

💡 Why This Matters

🌍 Real World

Setting up TestBed is essential for writing unit tests in Angular applications to ensure components work as expected.

💼 Career

Understanding TestBed configuration is a key skill for Angular developers to write maintainable and reliable tests.

1

Import and declare the component

Import TestBed and ComponentFixture from @angular/core/testing and import GreetingComponent from ./greeting.component. Then create a variable called fixture of type ComponentFixture<GreetingComponent> and a variable called component of type GreetingComponent.

Angular

// Import TestBed and ComponentFixture from '@angular/core/testing'
// Import GreetingComponent from './greeting.component'

// Declare fixture and component variables
// Your code here

Need a hint?

Use Angular's testing imports and declare variables for the fixture and component instance.

2

Configure TestBed with the component

Use TestBed.configureTestingModule to declare GreetingComponent in the declarations array. Then call TestBed.compileComponents() to compile the component.

Angular

import { TestBed, ComponentFixture } from '@angular/core/testing';
import { GreetingComponent } from './greeting.component';

let fixture: ComponentFixture;
let component: GreetingComponent;

// Configure TestBed with GreetingComponent and compile components
// Your code here

Need a hint?

Use beforeEach(async () => { ... }) to configure and compile the TestBed.

3

Create the component fixture and instance

Inside a beforeEach block, assign fixture by calling TestBed.createComponent(GreetingComponent). Then assign component to fixture.componentInstance. Finally, call fixture.detectChanges().

Angular

import { TestBed, ComponentFixture } from '@angular/core/testing';
import { GreetingComponent } from './greeting.component';

let fixture: ComponentFixture;
let component: GreetingComponent;

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

// Create fixture and component instance, then call detectChanges
// Your code here

Need a hint?

Create the component fixture and instance before each test and trigger change detection.

4

Write a test to check component creation

Write a test using it with the description 'should create GreetingComponent'. Inside the test, use expect(component) with toBeTruthy() to check if the component instance is created.

Angular

import { TestBed, ComponentFixture } from '@angular/core/testing';
import { GreetingComponent } from './greeting.component';

let fixture: ComponentFixture;
let component: GreetingComponent;

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

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

// Write a test to check if component is created
// Your code here

Need a hint?

Use it and expect to write a simple test that checks if the component exists.