Angular 如何测试处理局部变量并返回可观测值的角度服务方法？

假设这样的服务：

@Injectable()
export class PageNavService {
    private _expanded = true;
    private pageNavExpanded = new Subject<any>();

    public togglePageNav(): void {
        this._expanded = !this._expanded
        this.pageNavExpanded.next(this._expanded);
    }

    public setPageNavState(expanded) {
        this._expanded = expanded;
        this.pageNavExpanded.next(this._expanded);
    }

    public getPageNavState(): Observable<any> {
        return this.pageNavExpanded.asObservable();
    }

    constructor() { }
}

但是，由于以下原因，测试失败：

期望虚假成为真实

---

您应该调用方法

getPageNavState（）

 service.getPageNavState().subscribe((s) => {
            state = s;
 });

---

因为您的初始状态为

true

，所以测试无法成功，让我解释一下

describe('PageNavService', () => {
    let service;
    let state;

    beforeEach(() => TestBed.configureTestingModule({
        providers: [PageNavService]
    }));

    beforeEach(inject([PageNavService], svc => {
        service = svc;
        //At this moment, the state inside the service is true
        service.getPageNavState().subscribe((s) => {
            state = s;
        });
    }));

    describe('togglePageNav method', () => {
        it('should reverse the navbar state', () => {
            //Toggle will change the state from its initial state to an opposite one, making it false
            service.togglePageNav();
            //The test fails because the state is now false.
            expect(state).toBeTruthy();
        });
    });
});

---

您可以将初始状态（

private\u expanded

）更改为

false

，也可以将测试更改为期望

false

，因为这是您目前应该得到的结果。

getPageNavState

是一个方法，您必须调用它（

service.getPageNavState（）

而不是

服务。getPageNavState

）谢谢，这解决了语法错误，但测试仍然失败，就像未返回可观察对象一样。谢谢您的语法修复，但测试仍然失败。好像它没有被观察到，你是对的。一旦我解决了别人指出的语法错误，并且删除了前面的

expect（）。非常感谢。
describe('PageNavService', () => {
    let service;
    let state;

    beforeEach(() => TestBed.configureTestingModule({
        providers: [PageNavService]
    }));

    beforeEach(inject([PageNavService], svc => {
        service = svc;
        //At this moment, the state inside the service is true
        service.getPageNavState().subscribe((s) => {
            state = s;
        });
    }));

    describe('togglePageNav method', () => {
        it('should reverse the navbar state', () => {
            //Toggle will change the state from its initial state to an opposite one, making it false
            service.togglePageNav();
            //The test fails because the state is now false.
            expect(state).toBeTruthy();
        });
    });
});