class MyService {

  protected otherService: OtherService;

  constructor(os: OtherService) {
    this.otherService = ds;
  }

  public someMethod() {
    this.otherService.doSomething();
  }

}

describe('Launcher Renderer', () => {

    //dependencies (mocked)
    const os = sinon.mock(new OtherService());

    // the renderer class
    let underTest: MyService;

    before(() => {
        underTest = new MyService(os);
    });

    // actual tests,....
});

class MyService {

  protected otherService: OtherService | any;

  constructor(os: OtherService | any) {
    this.otherService = ds;
  }

  public someMethod() {
    this.otherService.doSomething();
  }

}