# Angular Unit Testing (Angular)

> Jasmine, Karma, TestBed, component testing, service testing, mocking, spies, async testing, fixture

- 22 interview questions
- Mid-Level
- [Interview Questions: Angular](https://sharpskill.dev/en/technologies/angular/interview-questions.md)

## 1. What is the main role of TestBed in Angular unit testing?

**Answer**

TestBed is the primary utility for configuring and creating an Angular testing module. It allows configuring providers, imports, declarations and instantiating components in an isolated test environment. TestBed creates a test context that simulates how an Angular NgModule works, enabling dependency injection and component compilation.

## 2. Which TestBed method should be used to get a service instance?

**Answer**

TestBed.inject() is the recommended method to get a service instance from the testing module injector. This method replaces the older TestBed.get() syntax (deprecated) and provides better TypeScript typing. It accesses services provided in the TestBed configuration via configureTestingModule.

## 3. What does the TestBed.createComponent() method return?

**Answer**

createComponent() returns a ComponentFixture, a wrapper around the component that provides access to the component instance (componentInstance), its DOM element (nativeElement), DebugElement, and testing methods like detectChanges(). The ComponentFixture is the central object for testing an Angular component.

## 19 more questions available

- What is the role of fixture.detectChanges() in a component test?
- How to create a Jasmine spy to mock a service method?

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## Other Angular interview topics

- [TypeScript Basics](https://sharpskill.dev/en/technologies/angular/interview-questions/typescript-basics.md): 25 questions, Junior
- [TypeScript Advanced](https://sharpskill.dev/en/technologies/angular/interview-questions/typescript-advanced.md): 20 questions, Junior
- [Angular Fundamentals](https://sharpskill.dev/en/technologies/angular/interview-questions/angular-fundamentals.md): 20 questions, Junior
- [Components & Lifecycle](https://sharpskill.dev/en/technologies/angular/interview-questions/components-lifecycle.md): 20 questions, Junior
- [Services & Dependency Injection](https://sharpskill.dev/en/technologies/angular/interview-questions/services-dependency-injection.md): 20 questions, Junior
- [Angular Modules Organization](https://sharpskill.dev/en/technologies/angular/interview-questions/modules-organization.md): 22 questions, Mid-Level
- [Angular CLI](https://sharpskill.dev/en/technologies/angular/interview-questions/angular-cli.md): 18 questions, Junior
- [Directives & Pipes](https://sharpskill.dev/en/technologies/angular/interview-questions/directives-pipes.md): 22 questions, Mid-Level
- [Routing & Navigation](https://sharpskill.dev/en/technologies/angular/interview-questions/routing-navigation.md): 24 questions, Mid-Level
- [Reactive Forms](https://sharpskill.dev/en/technologies/angular/interview-questions/forms-reactive.md): 26 questions, Mid-Level
- [Template-driven Forms](https://sharpskill.dev/en/technologies/angular/interview-questions/forms-template-driven.md): 16 questions, Mid-Level
- [RxJS Fundamentals](https://sharpskill.dev/en/technologies/angular/interview-questions/rxjs-fundamentals.md): 22 questions, Mid-Level
- [RxJS Operators](https://sharpskill.dev/en/technologies/angular/interview-questions/rxjs-operators.md): 24 questions, Mid-Level
- [HttpClient & API Calls](https://sharpskill.dev/en/technologies/angular/interview-questions/http-client.md): 22 questions, Mid-Level
- [Basic State Management](https://sharpskill.dev/en/technologies/angular/interview-questions/state-management-basics.md): 20 questions, Mid-Level
- [Change Detection](https://sharpskill.dev/en/technologies/angular/interview-questions/change-detection.md): 20 questions, Mid-Level
- [Angular Signals](https://sharpskill.dev/en/technologies/angular/interview-questions/angular-signals.md): 20 questions, Mid-Level
- [Standalone Components](https://sharpskill.dev/en/technologies/angular/interview-questions/standalone-components.md): 18 questions, Mid-Level
- [End-to-End Testing](https://sharpskill.dev/en/technologies/angular/interview-questions/testing-e2e.md): 18 questions, Mid-Level
- [Build & Optimization](https://sharpskill.dev/en/technologies/angular/interview-questions/build-optimization.md): 20 questions, Mid-Level
- [NgRx Fundamentals](https://sharpskill.dev/en/technologies/angular/interview-questions/ngrx-fundamentals.md): 24 questions, Senior
- [NgRx Advanced](https://sharpskill.dev/en/technologies/angular/interview-questions/ngrx-advanced.md): 24 questions, Senior
- [Angular Architecture](https://sharpskill.dev/en/technologies/angular/interview-questions/angular-architecture.md): 22 questions, Senior
- [Performance Optimization](https://sharpskill.dev/en/technologies/angular/interview-questions/performance-optimization.md): 22 questions, Senior
- [Security & Best Practices](https://sharpskill.dev/en/technologies/angular/interview-questions/security-best-practices.md): 20 questions, Senior
- [Advanced RxJS Patterns](https://sharpskill.dev/en/technologies/angular/interview-questions/advanced-rxjs-patterns.md): 22 questions, Senior
- [Angular Universal & SSR](https://sharpskill.dev/en/technologies/angular/interview-questions/angular-universal-ssr.md): 20 questions, Senior
- [Angular Micro-frontends](https://sharpskill.dev/en/technologies/angular/interview-questions/micro-frontends-angular.md): 20 questions, Senior

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