茉莉花：spyOn由导出的模块函数调用的非导出模块函数

Question

请参见下面的示例代码。我该如何spyOn notExportedFunction调用exportedFunction？

// some-module.ts

const notExportedFunction = (arg1: SomeType, arg2: SomeType) => 42
const export exportedFunction = (arg1: SomeType, arg2: SomeType): SomeOtherType => {
  const intermediateCalculation = notExportedFunction(arg1, arg2)
  // ...
  return whatever
}

// some-spec.ts

import { exportedFunction } from './some-module.ts'

describe('exportedFunction', () => {
  it('works', () => {
    spyOn(WHAT_DO_I_PUT_HERE, 'notExportedFunction').and.returnValue({})

    exportedFunction('foo', 'bar')
  })
})