How to mock non ng2 module? - unit-testing

Question

I'm working with a 3rd party module in my ng2 project. I want to be able to mock this module for testing, but the module itself doesn't get injected into my service, it's just required in.
How do I overwrite this Client so that my test isn't using the actual module?
import {Injectable} from '#angular/core';
var Client = require('ssh2').Client;
#Injectable()
export class SshService {
constructor(){
//Should log "hello world"
Client.myFunc();
}
}
import { TestBed, inject } from '#angular/core/testing';
describe('My Service', () => {
beforeEach(() => {
TestBed.configureTestingModule({
providers: [
SshService
]
});
});
it('should work as expected',
inject([SshService], (sshService:SshService) => {
sshService.Client = {
myFunc:function(){
console.log('hello world')
}
}
console.log(sshService.Client)
}));
});

Answer 1

You can't directly mock Client module for the test since it's required in the same file. You could wrap the Client in to a separate Angular service and inject that as a dependency:
import { Injectable } from '#angular/core';
import { TestBed, inject } from '#angular/core/testing';
let Ssh2 = require('ssh2');
#Injectable()
export class Ssh2Client {
public client: any = Ssh2.Client;
}
#Injectable()
export class Ssh2ClientMock {
// Mock your client here
public client: any = {
myFunc: () => {
console.log('hello world')
}
};
}
#Injectable()
export class SshService {
constructor(public client: Ssh2Client) {
client.myFunc();
}
}
describe('My Service', () => {
beforeEach(() => {
TestBed.configureTestingModule({
providers: [
SshService,
{ provide: Ssh2Client, useClass: Ssh2ClientMock }
]
});
});
it('should work as expected',
inject([SshService], (sshService: SshService) => {
sshService.client.myFunc() // Should print hello world to console
})
);
});

Answer 2

Maybe wrap the 3rd party module in a angular2 service and inject that service in the SshService.