How to mock/spy an imported function in Angular unit testing

Let's say i have an angular 6 component with a method test which returns some value:

import { doSomething } from './helper';

@Component({
...
})
export class AppComponent {
test() {
const data = doSomething(1);
return data.something ? 1: 2;
}
}


doSomething is just a simple helper function:

export function doSomething() {
return { something: 1 };
}


Is it possible to mock or spy this function in a unit test (so i can control its returnValue)? Or do i have to change my approach in the component?

Please note: doSomething() can be a lodash function, a const, a class etc. I just tried to keep the example as simple as possible.


Things i've tried:

• 
  SpyOn doesn't work because function is not attached to anything
  
  
• 
  Importing an mock-function into the imports array of TestBed.configureTestingModule gives Unexpected value 'doSomething' imported by the module 'DynamicTestModule'. Please add a @NgModule annotation.
  
  
• 
  Creating a service for it works but it feels silly to have to create services for each imported function
  

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