Receiving function prop as undefined

[Rafael Lages]

Hi guys Im having a weird problem where my component receive a function parameter as undefined if:
It is not declared in the same scope
OR
I don't declare and pass other variables on the same scope

describe('myTest', () => {
  let myComponent
  let myMock

  beforeEach(() => {
    myMock = jest.fn()
    myComponent = shallow(
      <MyComponent action={myMock} />
    )
  })
})

FAIL this.props.action is undefined

describe('myTest', () => {
  let myComponent

  beforeEach(() => {
    let myMock = jest.fn() // declared on the same block
    myComponent = shallow(
      <MyComponent action={myMock} />
    )
  })
})

WORKS this.props.action is my mock

describe('myTest', () => {
  let myComponent
  let myMock

  beforeEach(() => {
    myMock = jest.fn()
	let anything = 'anything' // anything else declared and passed in the same block
    myComponent = shallow(
      <MyComponent action={myMock} anything={anything}/>
    )
  })
})

WORKS this.props.action is my mock

my deps:

{
"jest": "^23.6.0",
"preact-cli": "^2.2.1",
"preact-render-spy": "^1.3.0",
"preact": "^8.4.2"
}

any ideas?
thanks