`ReferenceError: Cannot access 'myMock' before initialization` even though the rule is respected

🐛 Bug Report

I’m getting the error:

ReferenceError: Cannot access 'myMock' before initialization

Even though i respected jest documentation about the hoisting: A limitation with the factory parameter is that, since calls to jest.mock() are hoisted to the top of the file, it’s not possible to first define a variable and then use it in the factory. An exception is made for variables that start with the word ‘mock’.

what i’m doing:

import MyClass from './my_class';
import * as anotherClass from './another_class';

const mockMethod1 = jest.fn();
const mockMethod2 = jest.fn();
jest.mock('./my_class', () => {
  return {
    default: {
      staticMethod: jest.fn().mockReturnValue(
        {
          method1: mockMethod1,
          method2: mockMethod2,
        })
    }
  }
});

As you can see, i’m mocking a singleton class. The static method (here: staticMethod) is the entry point of my class.

To Reproduce

Steps to reproduce the behavior: Having a singleton class like so:

class MyClass {
  private instance

  private constructor(){ /* constructor thing */}

  static staticMethod(){
     if MyClass.instance { return MyClass.instance}

     /* do constructor etc....*/
     }
}
```

And i'm using this in the file I actually want to test:

```typescript
import MyClass from '/path/to/myClass'

const myClass = MyClass.staticMethod()

/* business logic goes here */

About the test file, you can see what i’m doing above.

Expected behavior

Not throwing ReferenceError: Cannot access 'myMock' before initialization when the rule about mock variable starting with mockis respected.

Link to repl or repo (highly encouraged)

envinfo

  System:
    OS: macOS 10.15.5
    CPU: (16) x64 Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz
  Binaries:
    Node: 12.18.4 - ~/.nvm/versions/node/v12.18.4/bin/node
    npm: 6.14.6 - ~/.nvm/versions/node/v12.18.4/bin/npm
  npmPackages:
    jest: ^26.6.3 => 26.6.3 

Thanks in advance for any help !

[kylegoetz]

This is happening to me, too:

index.test.ts:

const mockUseAuthToken = jest.fn()

jest.mock('../../../src/hooks/use-auth-token', () => ({
	useAuthToken: mockUseAuthToken,
}))

Jest output:

ReferenceError: Cannot access 'mockUseAuthToken' before initialization

       8 | 
       9 | jest.mock('../../../src/hooks/use-auth-token', () => ({

package.json:

"jest": "26.6.3"

This was working before upgrading Jest. Previously was on `26.0.1`.

[amitnsky]

You may use this:

import { X } from 'path/to/module'

jest.mock('path/to/module', () => ({
    X: jest.fn()
}));

in your test block::

expect(X).toHaveBeenCalled()