测试服务角

Question

我遇到了一个问题，我不知道如何解决它，因为我对前面的测试非常陌生。

现在我正在测试具有此代码的服务：

import { Injectable } from '@angular/core';
import { EndpointLocatorService } from './endpointLocator.service';
import { Http, Headers } from '@angular/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';

@Injectable()
export class CancelAppService {

    constructor(private readonly http: Http,
        private readonly _endPointLocator: EndpointLocatorService) { }

    getScopeSignature(signatureToken: string) {
        const url = this._endPointLocator.locate('cancelApp');
        const language = sessionStorage.getItem('languageSession');
        const headers = new Headers({
            'Content-Type': 'application/json',
            'Accept-Language': language,
            'X-B3-TraceId': sessionStorage.getItem('requestID')
        });
        const body = JSON.stringify({ 'signatureToken': signatureToken });
        return this.http.post(url, body, { headers }).map(data => {
            return data.json();
        }).catch((error: any) => {
            return Observable.throw(new Error(error.status));
        });
    }
}

测试文件包含以下内容：

import { TestBed } from '@angular/core/testing';
import { CancelAppService } from './cancelApp.service';
import { HttpModule } from '@angular/http';
import { EndpointLocatorService } from './endpointLocator.service';
import { AppConfig } from '../app.config';
import 'jasmine';

fdescribe('CancelAppService', () => {
    let cancelService: CancelAppService; // Add this
    let endLocator: EndpointLocatorService;
    const mockData = {
        "signature_token": "returnedToken"
    };
    const body = JSON.stringify({ 'signatureToken': 'givenToken' });
    beforeEach(() => {
        TestBed.configureTestingModule({
            imports: [
                HttpModule
            ],
            providers: [
                CancelAppService,
                AppConfig,
                EndpointLocatorService
            ]
        });
        cancelService = TestBed.get(CancelAppService); // Add this
        endLocator = TestBed.get(EndpointLocatorService);
    });

    it('should be created', () => { // Remove inject()
        expect(cancelService).toBeDefined();
    });

    it('should call the service', () => {
        spyOn(endLocator, 'locate').and.returnValue('someUrl');
        spyOn(cancelService, 'getScopeSignature').and.callThrough();
        cancelService.getScopeSignature(body);
        expect(cancelService.getScopeSignature).toHaveBeenCalled();
    });

    it('should return a object', () => {
        (done: DoneFn) => {
            spyOn(endLocator, 'locate').and.returnValue('someUrl');
            spyOn(cancelService, 'getScopeSignature').and.returnValue(mockData);
            cancelService.getScopeSignature(body).subscribe(data => {
                expect(data).toEqual(mockData);
                done();
            });
        }
    });
});

问题是，当我尝试测试返回的数据映射时，我看起来像是一个成功的测试，但覆盖率说我没有覆盖地图的线条，然后捕获。

知道我做错了什么吗？以及如何解决？

非常感谢！！

Answer 1

您正在模拟正在测试的服务，您应该模拟您的服务 EndpointLocatorService 甚至可能是 HttpClient 正在使用的服务，以尽量减少模拟。您可以通过单步执行代码来验证这一点。

让我在代码中解释为什么这些行没有被命中。

// In this example, the lines are hit, but after the test exited.
it('should call the service', () => {
    spyOn(endLocator, 'locate').and.returnValue('someUrl');
    spyOn(cancelService, 'getScopeSignature').and.callThrough();
    // Here you are calling a method yourself and checking that it was
    // called, it doesn't make sense, this test should make sure
    // You should check that your endLocator was called.
    // Note that because you are not waiting for the promise to resolve,
    // The test finishes before either callback is handled.
    cancelService.getScopeSignature(body);
    expect(cancelService.getScopeSignature).toHaveBeenCalled();
});


// In this example the lines in your test are never hit because you
// mocked it
it('should return a object', () => {
    (done: DoneFn) => {
        spyOn(endLocator, 'locate').and.returnValue('someUrl');
        // Here you are mocking getScopeSignature completely so it doesn't
        // Run any of your lines that you are trying to test
        // It just tests that you mocked it correctly
        spyOn(cancelService, 'getScopeSignature').and.returnValue(mockData);
        cancelService.getScopeSignature(body).subscribe(data => {
            expect(data).toEqual(mockData);
            done();
        });
    }
});

我无法重写您的测试，所以它实际测试它，因为它取决于EndpointLocatorService 的工作方式，您也可以选择在该级别模拟它。我通常选择在HttpClient 级别进行模拟，因为我可以从网络选项卡复制粘贴响应。

关键是您需要模拟服务使用的服务，而不是服务本身。您可以选择模拟组件使用的直接服务，也可以在更深层次上模拟。例如，您的EndpointLocatorService 可能需要调用HttpClient，您可以选择模拟任一服务。

见https://angular.io/guide/testing#httpclienttestingmodule 和https://alligator.io/angular/testing-httpclient/