message: feat(modal): add test case for id unspecified case in config (ModalOptions)
diff: @@ -2,6 +2,7 @@ import { Component, NgModule } from '@angular/core';
  import { TestBed, ComponentFixture } from '@angular/core/testing';
  import { BsModalService, ModalModule } from '../modal';
  +import { pairwise, tap } from 'rxjs/operators';
  /* tslint:disable-next-line: max-classes-per-file */
  @Component({ template: '<div>Dummy Component</div>' })
  @@ -49,6 +50,20 @@ describe('Modal service', () => {
  modalService.show(TestModalComponent);
  });
  + it('should return different random id when open nested modal without specifying id', done => {
  + modalService.onShown.pipe(
  + pairwise(),
  + tap(([firstData, secondData]) => {
  + /* tslint:disable-next-line: no-floating-promises */
  + expect(firstData.id).not.toBe(secondData);
  + done();
  + })
  + ).subscribe();
  +
  + modalService.show(TestModalComponent);
  + modalService.show(TestModalComponent);
  + });
  +
  it('should return id in config when specified', done => {
  const id = 20;
  