How to mock js import in angular 5 in tests?

Question

I'm trying to write tests for an angular 5 application which uses a js import, I've been doing research but i cant seen to figure out how to mock the js import. In the test, I just want to check that the bar() method has been called using a spyOn but can't figure out how to do this. import {foo} from 'fooProject'; export class Component { constructor(){} trigger() { foo.bar(); } } JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

One option is you can create a factory method for foo and then register that factory in the providers for the module. Then, in your unit test, you can inject whatever you want and fake the members. import {foo} from 'fooProject'; export function fooFactory(): any { return foo; } @NgModule({ providers: [{ provide: 'Foo', useFactory: fooFactory }] }) export class YourModule { } import { Inject, Component } from '@angular/core'; export class YourComponent { constructor(@Inject('Foo') private foo:any){} trigger() { this.foo.bar(); } }