Jest test for helper file and external function

I need to add jest test into the current project. however i found that a helper files here i don't know how to write the test for it

the file stores some functions like this

import SDK from 'privateSDK'

export function login(){
  SDK.login() // Call the native app login if webview
}

If you run the functions on browser on PC, you will not get any data or effects How Can I test the file?