Tools.spec.js

import { expect } from 'chai';
const proxyquire = require('proxyquire').noCallThru();

const requestsMock = { get: null };

const Tools = proxyquire('../Tools', {
  '../../../utils/api/requests': requestsMock,
});

describe('Tools', () => {
  describe('fileExists', () => {
    it('should return true if the file exists', () => {
      requestsMock.get = () => ({ status: 200, json: () => Promise.resolve('exists') });
      const exists = Tools.fileExists('foobar.txt');
      return exists.then(v => expect(v).to.be.true);
    });

    it('should return false if the file doesnt exist', () => {
      requestsMock.get = () => ({ status: 400 });
      const exists = Tools.fileExists('foobar.txt');
      return exists.then(v => expect(v).to.be.false);
    });
  });