Question

我有一个Angular服务，需要将配置对象传递给该服务：

// my.module.ts
@NgModule({ ... })
export class MyModule {
    static forRoot(config: MyServiceConfig): ModuleWithProviders {
        return {
            ngModule: MyModule,
            providers: [{ provide: MyServiceConfig, useValue: config }],
        };
    }
}


//my.service.ts
export class MyService {
        constructor(private _http: HttpClient, @Optional() config: MyServiceConfig) {
        if (config) {
            if (!config.attr1) {
                throw new Error('You must provide the attr1 to use this Module.');
            } else if (!config.attr2) {
                throw new Error('You must provide the attr2 to use this Module.');
            } else {
                this.attr1 = config.attr1;
                this.attr2 = config.attr2;
            }
        } else {
            throw new Error(
                'You must provide a MyServiceConfig object with the attr1 and the attr2 to use this module.',
            );
        }
    }

}

这一切都可行，但是我想围绕向该服务提供该配置对象编写一些测试。我在测试文件中有以下beforeEach，当未提供配置对象时，它按预期抛出了错误：

beforeEach(() => {
    TestBed.configureTestingModule({
        imports: [HttpClientTestingModule],
        providers: [FeedbackService],
    });
});

但是当我尝试将其移出beforeEach并进行单个测试时，我无法正确地抛出错误。如果完全按照上面的方式调用它，但在测试中，它将：

it('should do something', () => {
    TestBed.configureTestingModule({
        imports: [HttpClientTestingModule],
        providers: [FeedbackService],
    });
});

我在try/catch块中尝试了上述操作，试图捕获错误，但这给了我误报。我尝试了expect(() => {}).toThrowError()和toThrow()方法，但是即使将TestBed.configureTestingModule()放在期望的箭头函数中也无法正常工作。这样就不会引发错误。

有没有办法做到这一点？另外，是否有一种方法可以向服务提供配置对象，以测试是否将服务属性设置为正确的值？

Answer 1

只需为config对象提供一个值：

describe("FeedbackService", ()=>{
    beforeEach(() => {
        TestBed.configureTestingModule({
            imports: [HttpClientTestingModule],
            providers: [FeedbackService]
        });
    });

    describe("when config object is provided", ()=>{
        let dummyConfig : Object;
        beforeEach(()=>{
          dummyConfig = {/* set some properties*/};
          TestBed.overrideProvider(MyServiceConfig, {useValue: dummyConfig});
        });

        it("should not explode", ()=>{
          // a test in which the config object is dummyConfig
        });
    });
});

边注：：我没有看到用@Optional装饰配置对象的意义，并且在没有提供令牌值的情况下抛出该问题。您基本上是在重新实现默认未提供的逻辑。

Answer 2

我使用了@ Jota.Toledo的一些答案并进行了编辑，以获取以下测试文件：

import { TestBed } from '@angular/core/testing';

import { MyService } from './my.service';
import { MyServiceConfig } from './my-service-config';

describe('MyService', () => {
    beforeEach(() => {
        TestBed.configureTestingModule({
            imports: [HttpClientTestingModule],
            providers: [MyService],
        });
    });

    describe('config object provided', () => {
        let config: MyServiceConfig;
        const attr1 = 'https://my-test-api.test.com';
        const attr2 = 'testing';

        beforeEach(() => {
            config = null;
        });

        it('should use the values passed in the config for the attr1 and attr2', () => {
            config = { attr1, attr2 };
            TestBed.overrideProvider(MyService, { useFactory: () => new MyService(null, config) });
            const service: MyService = TestBed.get(MyService);

            expect(service.attr1).toBe(attr1);
            expect(service.attr2).toBe(attr2);
        });

        it('should throw an error if config object is provided but not the attr1 attribute', () => {
            try {
                config = { attr1: null, attr2 };
                TestBed.overrideProvider(MyService, { useFactory: () => new MyService(null, config) });
                const service: MyService = TestBed.get(MyService);
            } catch (e) {
                expect(e.message).toBe('You must provide the api URL to use this module.');
            }
        });

        it('should throw an error if config object is provided but not the attr2 attribute', () => {
            try {
                config = { attr1, attr2: null };
                TestBed.overrideProvider(MyService, { useFactory: () => new MyService(null, config) });
                const service: MyService = TestBed.get(MyService);
            } catch (e) {
                expect(e.message).toBe('You must provide the feedback source to use this module.');
            }
        });
    });

    describe('config object not provided', () => {
        beforeEach(() => {
            TestBed.overrideProvider(MyService, { useFactory: () => new MyService(null, null) });
        });
        it('should throw an error if no config object provided', () => {
            try {
                const service: MyService = TestBed.get(MyService);
            } catch (e) {
                expect(e.message).toBe(
                    'You must provide a MyServiceConfig object with the attr1 and the attr2 to use this module.',
                );
            }
        });
    });
});

这应该在应该发生的时候正确地抛出了错误，并且我能够检查message属性以确保它在正确的时间抛出了正确的错误。

角度测试：如何通过TestBed向服务类提供配置对象？

2 个答案: