Basic typescript stubs

stub.ts

export function stub<T>(): T {
  const typeAssertion = {} as T;
  for (const prop in typeAssertion) {
      if (typeAssertion.hasOwnProperty(prop)) {
          typeAssertion[prop] = undefined;
      }
  }

  return typeAssertion;
}

usage.ts

import * from 'stub'

const amplifyStub = stub<AmplifyService>();
amplifyStub.authStateChange$ = Observable.create();
amplifyStub.auth = () => {};