Cannot read property '_root' of undefined react native jest testcases

I am trying to run testcases in my project, one scenario is to mock the function and validate output. In that function I have used Toast.show(). Whenever I am trying to run that function through testcases, it gives me below error.

Cannot read property '_root' of undefined

Steps to reproduce

Create a function in React native component which will show Toast. Write test case to mock that class and run that function.

First.test.js

describe("Dashboard Component", () => {
  it("should call onFunctionCall", () => {
    const wrapper = shallow(
        <Dashboard navigation={navigation} />
    ).dive().dive().dive().dive()

    const onFunctionCall = jest.spyOn(wrapper.instance(), "onFunctionCall")
    wrapper.update()
    wrapper.instance().forceUpdate()
    wrapper.instance().onFunctionCall()

    expect(onFunctionCall).toHaveBeenCalled()
  })
})

I have reported this issue over their repo also, take a look https://github.com/GeekyAnts/NativeBase/issues/3075