Invalid provider for the NgModule 'DynamicTestModule' when testing a service in Angular 2

Question

I have the following service:

import { Injectable } from '@angular/core';  import { MenuItem } from './../classes/menu-item'; import { ITEMS } from './../static-data/items-list';  @Injectable() export class ItemsListService {      getItems(): Promise<MenuItem[]> {         return Promise.resolve(ITEMS);     }  } 

The test for this service is here:

import { TestBed, async, inject } from '@angular/core/testing';  import { ItemListService } from './item-list.service'; import { MenuItem } from './../classes/menu-item'; import { ITEMS } from './../static-data/items-list';  describe('ItemListService', () => {   beforeEach(() => {     TestBed.configureTestingModule({         providers: [ ItemListService, MenuItem, ITEMS ]     });   });    it('should ...', inject([ItemListService], (service: ItemListService) => {     expect(service).toBeTruthy();   })); }); 

The MenuItem is defined here:

export class MenuItem {     name: string;     link: string; } 

ITEMS is defined here: import { MenuItem } from './../classes/menu-item';

export var ITEMS: MenuItem[] = [     {name: 'Vehicles', link: '/vehicles'},     {name: 'Gateways', link: '/gateways'},     {name: 'Statuses', link: '/statuses'},     {name: 'Logs', link: '/logs'} ] 

When I run the test I am getting in the browsers console the followings errors:

FAILED ItemListService should ... 

and

So why do I have these errors? And what is the solution for the test to work?

Answer 1

This is such an annoying error, thought I'd include another subtle cause to look for in your spec. In my case I specified providers instead of the correct value of provide as below

 TestBed.configureTestingModule({       providers: [{provider: ApplicationActions, useClass: ActionMock}] 

rather than offer useful information like "no 'provide' key specified" it simply reports

Failed: Invalid provider for the NgModule 'DynamicTestModule' - only instances of Provider and Type are allowed, got: [?[object Object]?, ...]