I am struggling to mock rxjs functions using sinon. Usually I import a library as an object and mock the function I need;

// example.test.ts
import * as Rxjs from "rxjs";
import { stub } from "sinon";
import { equal } from "assert";
import { example } from "./example";

const throwErrorStub = stub(Rxjs, "throwError");

example();

equal(throwErrorStub.called, true); // fails

// example.ts
import { throwError } from "rxjs";

const export example = () => {
  throwError(() => new Error("Test"));
}

All other object / library mocks work within the test – just none of the rxjs functions.