Is there a way to verify the functionality of this Angular 2 service?

In my Angular application, there is a service called BookService:

import { Injectable } from '@angular/core';
import { Http } from '@angular/http';

@Injectable()
export class BookService {

  constructor(private http: Http) {}

  getList() {
    return this.http.get('/api/books.json');
  }
}

I am wondering how to properly test the getList() function.

I don't need all the specifics, just some guidance. I know that testing services like this is common practice, but I'm struggling to find clear documentation on the process. Once I have a general direction to follow, I can delve into the details on my own.

Answer №1

import {addProviders, inject} from '@angular/core/testing';

describe('testing my code', () => {
  beforeEach(() => {
    addProviders([
      BookService, 
      HTTP_PROVIDERS,
      MockBackend,
      {provide: XHRBackend, useMock: MockBackend}]);
  });

  it('performs a task', inject([BookService], (service) => {
    // implementation of the test
  });
});

To learn more, visit https://angular.io/docs/ts/latest/api/http/testing/MockBackend-class.html

Answer №2

After tinkering with it independently, I developed the following code snippet for the test itself:

  it('should assign a list of books', inject([BookService, MockBackend, Http], (bookService, backend, http) => {
    backend.connections.subscribe(connection => {
      var mockResponse = new Response(new ResponseOptions({
        body: [{ name: 'Whiteboard Interviews' }]
      }));
      connection.mockRespond(mockResponse);
    });

    let service = new BookService(http);
    service.getList().subscribe(response => {
      expect(response.json()).toEqual([{ name: 'Whiteboard Interviews' }]);
    });
  }));

Here is the complete spec file:

/* tslint:disable:no-unused-variable */

import { provide } from '@angular/core';
import { MockBackend } from '@angular/http/testing';

import {
  Http,
  HTTP_PROVIDERS,
  Response,
  ResponseOptions,
  BaseRequestOptions,
  ConnectionBackend
} from '@angular/http';

import {
  beforeEach, beforeEachProviders,
  describe, xdescribe,
  expect, it, xit,
  async, inject
} from '@angular/core/testing';

import { BookService } from './book.service';

describe('Book Service', () => {
  beforeEachProviders(() => [
    BookService,
    HTTP_PROVIDERS,
    MockBackend,
    BaseRequestOptions,
    provide(Http, {
      useFactory: function (backend:ConnectionBackend, defaultOptions:BaseRequestOptions) {
        return new Http(backend, defaultOptions);
      },
      deps: [MockBackend, BaseRequestOptions]
    })
  ]);

  it('should ...',
      inject([BookService], (service: BookService) => {
    expect(service).toBeTruthy();
  }));

  it('should assign a list of books', inject([BookService, MockBackend, Http], (bookService, backend, http) => {
    backend.connections.subscribe(connection => {
      var mockResponse = new Response(new ResponseOptions({
        body: [{ name: 'Whiteboard Interviews' }]
      }));
      connection.mockRespond(mockResponse);
    });

    let service = new BookService(http);
    service.getList().subscribe(response => {
      expect(response.json()).toEqual([{ name: 'Whiteboard Interviews' }]);
    });
  }));
});

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

What is the best way to pass data between sibling components in Angular?

Within my Angular application, I have three sibling components that share a variable called "data". This data contains sensitive information related to API endpoints for determining discounts. Due to security concerns, passing this data through the router ...

Having trouble resolving npm install -g @angular/cli due to issue with checking the installable status of [email protected] module

When attempting to install @angular/cli using the npm command in the command prompt, I encountered an issue with resolveWithNewModule. It seems to be stuck at checking installable status.[email protected] ...

Error: Invalid character '&' after initializing create-t3-application bootstrap

After initiating a new next.js app with the command npm create t3-app@latest, I encountered an unexpected syntax error when running the app using npm run dev. The error displayed was SyntaxError: Unexpected token '??='. Additionally, my console o ...

Troubleshooting issues encountered while sending HttpClient Get Requests from Angular Front-End to Node.js Back-End

I am encountering an issue where I keep getting the error message "Cannot GET /" on my local host URL when attempting to send a HttpClient get request from my Angular front-end to my Node.js back-end endpoint. Despite the fact that my back-end endpoint suc ...

I have encountered challenges trying to consume form data containing a zip file and several other parameters sent from an Angular 2 frontend in my Java backend

I keep encountering the issue with error code 415 Unsupported media type. My current process involves sending form data with a zipped file along with several other parameters. I have set the content type as multipart/form-data in Angular 2. On the Java ...

My inquiry was met with silence from the Angular project

I have encountered an issue with my dockerized angular project. Upon starting my container, it appears that the 4200 port is already in use, even though the CMD command within the container does not initiate the application startup. Here is how my Docke ...

Setting up Electron with React and TypeScript: A Comprehensive Guide

I've been developing an app using Electron, React (jsx), and Babel. However, I recently made the switch to TypeScript and I'm struggling to get everything functioning properly. The npm packages I've tried only work for either React or TypeSc ...

Tips for adding a time increment of 24 hours to a date variable in Angular 6

My goal is to update a date variable called EndDate stored in localStorage by adding exactly 24 hours to it. The current value in the localStorage is Sun Jun 09 2019 20:39:44 GMT+0530 (India Standard Time). var endDate = new Date(); endDate.setDat ...

Encountering an error when attempting to access undefined property while using a method as a callback

Exploring OOP and angular is new to me. I am currently trying to implement a reusable table with pagination that triggers an API request when the page changes (pagination within the table component). The issue arises when I attempt to access my method usi ...

The powerful combination of Visual Studio 2015, TypeScript, Cordova, Angular 2, and System

I am encountering an issue with the loading of external modules using systemJS. I have created a small sample project for VS2015. Feel free to check out the code here: https://github.com/dbiele/TypeScript-Cordova-SystemJS After building the project and at ...

Several mat-radio-button options chosen within mat-radio-group

`<mat-radio-group [ngClass]="cssForGroup" name="test"> <mat-radio-button *ngFor="let option of options | filter:searchText" class="cssForRow" [value]="option" ...

Challenges with integrating a Bootstrap 4 table into a card component

Here is a problem I am facing. It seems that the table inside the card is not displaying correctly. I want the table to be centered or at least eliminate the blank space that is currently showing. Here is my code (using Angular 6): <div class="row ...

What is the function return type in a NextJS function?

In my project using NextJS 13, I've come across a layout.tsx file and found the following code snippet: export default function RootLayout({ children }: { children: React.ReactNode }) { return ( <html> <head /> <body&g ...

Challenges with importing and using jspdf and autotable-jspdf in Angular 8

Issue with Generating PDF Using Angular 8, JSPDF, and JSPDF-AutoTable I am facing a challenge with exporting/generating a PDF based on an HTML grid. I need to make some DOM changes with CSS, remove toggle buttons, alter the header, etc. However, all the s ...

Is there a way to dynamically assign values to [routerLink] based on the elements in an array?

Looking to create a dynamic routing within my template. The routing values are sourced from an array that is being iterated through with ngFor. Additionally, I need to perform some transformations on these string values. Any help would be appreciated. En ...

Can you show me the correct way to use Test::Exception in Perl with Selenium, along with a good

When using selenium IDE with the perl driver/formatter, a default code template includes the following line: use Test::Exception; I have some questions regarding this module in relation to Test::WWW::Selenium. Should I use Test::Exception in my .t files ...

Is there a way for me to implement a "view more posts" button on

I need help figuring out how to hide the "Show More" button when there are no posts. I have created a showLoad function and an isLoad state variable, but I'm unsure of how to implement this. The button display logic is dependent on the isLoad state. ...

Tips for effectively crafting a component capable of managing both a value and an observable for that specific value

I'm actually curious about two things. When is it appropriate to pass an observable of an object into a component versus resolving it with the | async method? If I want to create a versatile reusable component that can handle both scenarios - accept ...

Is there a way to access the name of a generic type T class in TypeScript?

I'm currently working on incorporating the Service Locator pattern into my TypeScript project. Below is the snippet of my code: //due to only partial knowledge of TypeScript private static serviceMap: Map<string, any>; public static get& ...

Steps to execute an Angular directory within a project

Click here for imageWhenever I try to run ng serve command from the directory, it doesn't seem to work and just takes me back to the same directory. I'm having trouble running my Angular project. Any suggestions on how to solve this issue? ...