为什么我的茉莉花用ngOnInit中的方法测试组件确实失败了？

Question

我正在为组件编写测试以检查其真实性。组件的ngOnInit（）从本地存储中检索数据，并具有设置一些数据的方法

我的组件：

ngOnInit(){
  this.recordState =  JSON.parse(localStorage['mystate']);
      this.populateData();

}

我的测试：

beforeEach(() => {
    fixture = TestBed.createComponent(TestComponent);
    component = fixture.componentInstance;
    spyOn(localStorage, 'getItem').and.callFake((key: string): String => {
      return JSON.stringify({'mystate': {'testtext': 'hello'}});
  });
  fixture.detectChanges();
});

     it('should create', () => {  
        expect(component).toBeTruthy();
      });

错误：

should create FAILED
        SyntaxError: Unexpected token u in JSON at position 0
            at JSON.parse (<anonymous>)
            at TestComponent.ngOnInit (webpack:///./src/app/TestComponent?:22:46)
            at checkAndUpdateDirectiveInline (webpack:///./node_modules/@angular/core/fesm5/core.js?:9547:19)
            at checkAndUpdateNodeInline (webpack:///./node_modules/@angular/core/fesm5/core.js?:10811:20)
            at checkAndUpdateNode (webpack:///./node_modules/@angular/core/fesm5/core.js?:10773:16)
            at debugCheckAndUpdateNode (webpack:///./node_modules/@angular/core/fesm5/core.js?:11406:38)
            at debugCheckDirectivesFn (webpack:///./node_modules/@angular/core/fesm5/core.js?:11366:13)
            at Object.eval [as updateDirectives] (ng:///DynamicTestModule/SearchActionsComponent_Host.ngfactory.js:10:5)
            at Object.debugUpdateDirectives [as updateDirectives] (webpack:///./node_modules/@angular/core/fesm5/core.js?:11358:21)