使用Jest模拟和取消模拟命名的导入

Question

I've been reading about this in the official documentation , in this blogpost , and this issue in jest repo . Neither the documentation or the blogpost cover the scenario I'm trying to test. The issue thread does cover it, but I can't get the tests to pass using any of the solutions proposed there.

Can you complete the following code to make the tests pass?

Edit : To be clearer, I want to know how to mock the imported functions in a way that I can still use the original implementation in some tests and the mock in others.

These foo and bar functions may seem very simple and a small change in the implementation could make the tests pass, but the question that I have is about mocking.

For a bit more context I'm actually trying to test two sagas defined in the same file that have side effects that I don't want to run. I still want to unit test each of those sagas separately

// a.js
export const foo = () => 'foo-' + bar()
export const bar = () => 'bar'

// a.test.js
import {
  foo,
  bar
} from './a'

describe('foo', () => {
  it('should return foo-MOCKED_BAR', () => {
    expect(foo()).toBe('foo-MOCKED_BAR')
  })

  it('should have the mocked implementation of bar', () => {
    expect(bar()).toBe('MOCKED_BAR')
  })
})

describe('bar', () => {
  it('should have the original implementation of bar', () => {
    expect(bar()).toBe('bar')
  })
})

describe('foo and bar together', () => {
  it('should have the original implementation of both', () => {
    expect(foo()).toBe('foo-bar')
  })
})

Thanks!

Answer 1

i dont really use the framework but this should work

 //a.js export const foo = (arg) => 'foo-' + bar(arg) export const bar = (arg) => arg ? 'bar' : 'MOCKED_BAR' //a.test.js describe('foo', () => { it('should return foo-MOCKED_BAR', () => { expect(foo(0)).toBe('foo-MOCKED_BAR') }) it('should have the mocked implementation of bar', () => { expect(bar(1)).toBe('MOCKED_BAR') }) }) describe('bar', () => { it('should have the original implementation of bar', () => { expect(bar(1)).toBe('bar') }) }) describe('foo and bar together', () => { it('should have the original implementation of both', () => { expect(foo(1)).toBe('foo-bar') }) })