wip(test): add text normalization test

[andrewda]

Question	Response
Version?	all
Devices tested?	n/a
Bug fix?	no
New feature?	no
Includes tests?	yes
All Tests pass?	yes*
Related ticket?	#518

---

Description

Adds a test for the text-normalize file. Currently WIP.

[andrewda]

Need to figure out how to reset the mock each time. The first run mockRequiredClasses values are carried on to all the remaining tests. Not sure how to fix this.

[coveralls]

Coverage increased (+0.8%) to 47.811% when pulling 3d027d8 on test-normalize into dd2a50c on master.

[alejandronanez]

@andrewda have you tried with beforeEach / afterEach?

[andrewda]

@alejandronanez What should I use them for?

[alejandronanez]

@andrewda I think you can reset the mock for every test that is run. (or I am just misunderstanding everything 😞 )

[andrewda]

Yea, but I'm not sure how to reset just the Dimension and PixelRatio mocks, instead of everything (like the ones defined in testenv.js).

[machour]

@andrewda I had a look at this PR and after a lot of trial and error, the only working thing I can come up with is chaining .mockReturnValueOnce() calls:

jest.mock('Dimensions', () => ({
  get: jest
    .fn()
    .mockReturnValueOnce(mockScreens.iPhone5)
    .mockReturnValueOnce(mockScreens.iPhone6),
}));
jest.mock('PixelRatio', () => ({
  get: jest
    .fn()
    .mockReturnValueOnce(2)
    .mockReturnValueOnce(2),
}));

describe('Normalize Text', () => {
  // iOS Devices

  it('should normalize correctly on iPhone 5', () => {
    const { normalize } = require('config');
    expect(normalize(1)).toEqual(0.95);
  });

  it('should normalize correctly on iPhone 6', () => {
    const { normalize } = require('config');
    expect(normalize(1)).toEqual(0.95);
  });

This require a change in the src/config/normalize-text.js file where Dimensions.get('window') is currently called twice (and as we mock once, a single test ends up consuming two mocks).

[chinesedfan]

How about jest.unmock(moduleName)?

[machour]

Didn't work for me. If you console.log() in mockClassWithGetter , you'll see the log only once

[chinesedfan]

Jest@24 provides jest.isolateModules(fn). I think it is what we want.

[andrewda]

Closing in favor of #899 (thanks @chinesedfan!)