Jest depends on mock function variable name

[MathObsessed]

Hello, kind people!

I'm very puzzled at the moment with the following behaviour:

const mockRequestHandler = jest.fn(async context => (context.body = ''))

jest.mock('../requestHandler', () => mockRequestHandler)

const server = require('../server')
const request = require('supertest')

afterEach(() => {
    server.close()
    jest.clearAllMocks()
})

it('Returns HTTP code 200 on GET request to "/"', async () => {
    const response = await request(server).get('/')

    expect(mockRequestHandler).toHaveBeenCalledTimes(1)
    expect(response.status).toBe(200)
})

This code works. But once I change the variable name from "mockRequestHandler" to "requestHandler" or "requestHandlerMock" Jest throws an exception:

babel-plugin-jest-hoist: The module factory of `jest.mock()` is not allowed to reference any out-of-scope variables.
    Invalid variable access: requestHandlerMock

[thymikee]

Can you please follow the bug report template and add a repro?

[SimenB]

Yeah, this is expected. Since we hoist jest.mock calls, most initializing code does not run. You can tell Jest that you know what you're doing by prefixing the variable with mock

[github-actions]

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