how properly mock multiple useSelector hooks

Question

my component has multiple selectors:

import { useSelector } from 'react-redux'
...
const data1 = useSelector(xxxxx)
const data2 = useSelector(yyyyy)

How properly mock each in test file?

import { useSelector } from 'react-redux'
jest.mock('react-redux', () => ({
    useSelector: jest.fn()
}))
....
useSelector.mockImplementation(() => ({
   dataready: true
}))

which selector it's really mocking in this case?

Answer 1

Don't mock the selector. You want to test the integration between Redux and React components, not the Redux implementation of selectors. If you use react-testing-library it's pretty simple to hijack the render() method and implement your store using a Redux Provider component. Here are the docs for setting up a reusable render function.

Here's your test re-written with the user in mind:

import { renderWithProviders } from '../../test-utils' // <-- Hijacked render

// Explanation of behavior
it('displays data when ready', { 
  renderWithProviders(<YourComponent />, { 
    preloadedState: {
      someSlice: {
        dataready: true // <-- Pass data for selector in store slice
      }
    }
  })

  // Check that something shows based on selector
  expect(screen.getByTestId('some-testId')).toBeInTheDocument()
})