How to mock a import?

Question

I am working on a tdd project with Node.js and Typescript. I have a class named HttpSample which is imported to another class named Sample as follows.

import {HttpSample} from "./httpService"

...

const http: HttpSample = new HttpSample();
http.get();

How can I mock the HttpSample class inside the Sample's test file?

Update

I am using Jasmine and mocha frameworks

what testing framework are you using? they should have the concept of stubs / mocks? — Lyubomir, Aug 13 '18 at 09:49
think this should answer your question: https://stackoverflow.com/questions/35240469/how-to-mock-the-imports-of-an-es6-module — Lyubomir, Aug 13 '18 at 09:52
@lustoykov this is for JavaScript I want a solution for TypeScript — Lasitha Yapa, Aug 13 '18 at 10:04
Anything working in Javascript will work in Typescript as well — Aleksey L., Aug 13 '18 at 10:48
Imports can be mocked on non-native modules. Where is `const http: HttpSample` located? Is it in function scope? Please, update the code, `...` is not specific enough, the solution depends on it. — Estus Flask, Aug 13 '18 at 13:51

score 1 · Accepted Answer · answered Sep 10 '18 at 09:31

ts-mock-imports is a library that is designed to fix this issue in Typescript while remaining type safe. It's built on top of sinon instead of Jasmine but will play nice with both.

In sample.spec.ts

import * as httpSample from './httpService';
import { ImportMock } from 'ts-mock-imports';
import { Sample } from './sample';

const httpMock = ImportMock.mockClass(httpSample, 'HttpSample');

// Sample will now get a mock version of HttpSample
const sample = new Sample();

How to mock a import?

1 Answers1