how to change jest mock function return value in each test?

Question

I have a mock module like this in my component test file

  jest.mock('../../../magic/index', () => ({     navigationEnabled: () => true,     guidanceEnabled: () => true   })); 

these functions will be called in render function of my component to hide and show some specific feature.

I want to take a snapshot on different combinations of the return value of those mock functions.

for suppose I have a test case like this

 it('RowListItem should not render navigation and guidance options', () => {     const wrapper = shallow(       <RowListItem type="regularList" {...props} />     );     expect(enzymeToJson(wrapper)).toMatchSnapshot();   }); 

to run this test case I want to change the mock module functions return values to false like this dynamically

jest.mock('../../../magic/index', () => ({     navigationEnabled: () => false,     guidanceEnabled: () => false   })); 

because i am importing RowListItem component already once so my mock module wont re import again. so it wont change. how can i solve this ?

Answer 1

You can mock the module so it returns spies and import it into your test:

import {navigationEnabled, guidanceEnabled} from '../../../magic/index'  jest.mock('../../../magic/index', () => ({     navigationEnabled: jest.fn(),     guidanceEnabled: jest.fn() })); 

Then later on you can change the actual implementation using mockImplementation

navigationEnabled.mockImplementation(()=> true) //or navigationEnabled.mockReturnValueOnce(true); 

and in the next test

navigationEnabled.mockImplementation(()=> false) //or navigationEnabled.mockReturnValueOnce(false); 

Answer 2

what you want to do is

import { navigationEnabled, guidanceEnabled } from '../../../magic/index';     jest.mock('../../../magic/index', () => ({   navigationEnabled: jest.fn(),   guidanceEnabled: jest.fn() }));  describe('test suite', () => {   it('every test', () => {     navigationEnabled.mockReturnValueOnce(value);     guidanceEnabled.mockReturnValueOnce(value);   }); }); 

you can look more about these functions here =>https://facebook.github.io/jest/docs/mock-functions.html#mock-return-values