Use jest.requireActual() inside jest.mock()

jest.requireActual(moduleName)

Returns the actual module instead of a mock, bypassing all checks on whether the module should receive a mock implementation or not.

Example

I prefer this concise usage where you require and spread within the returned object:

// myModule.test.js

import { otherFn } from './myModule.js'

jest.mock('./myModule.js', () => ({
  ...(jest.requireActual('./myModule.js')),
  otherFn: jest.fn()
}))

describe('test category', () => {
  it('tests something about otherFn', () => {
    otherFn.mockReturnValue('foo')
    expect(otherFn()).toBe('foo')
  })
})

This method is also referenced in Jest’s Manual Mocks documentation (near the end of Examples):

To ensure that a manual mock and its real implementation stay in sync, it might be useful to require the real module using jest.requireActual(moduleName) in your manual mock and amending it with mock functions before exporting it.