我正在使用angular2 rc 5，我编写了一个从json获取值的自定义管道。自定义管道：literal.pipe.ts看起来像：
import {Pipe, PipeTransform, Inject} from '@angular/core';
import {MessageService} from '../service/message.service';
@Pipe({
name: 'literalString',
pure: false
})
export class LiteralPipe implements PipeTransform{
private messageBundle:any;
private request:any;
constructor(private _messageService: MessageService){
this._messageService = _messageService;
this.messageBundle = {};
}
transform(value:string, args:string[]):any {
if(!this.request){
this.request = this._messageService.getBundle();
this.request.subscribe(
(data:any) => this.messageBundle = data
);
}
if(this.messageBundle[value])
return this.messageBundle[value];
else if(args[0])
return args;
else
return "String not available. Pls include in bundle.json";
}
}
MessageService.ts：
import {Injectable} from "@angular/core"
import {Http} from '@angular/http';
import 'rxjs/Rx'
@Injectable()
export class MessageService{
http:any;
constructor(http: Http){
this.http = http;
}
getBundle (){
return this.http.get('../src/bundle.json').map((res:any) => res.json());
}
}
Bundle.json的键值对为
{
"Home.title": "Login",
"DashBoard.Title": "Dashboard",
"CheckOutGiftCard.Title": "GIFT CARD CHECKOUT"
}
我正在使用liteServer运行我的单元测试。我的unitTests.html：
<meta http-equiv="content-type" content="text/html;charset=utf-8">
<title>Ng App Unit Tests</title>
<link rel="stylesheet" href="../node_modules/jasmine-core/lib/jasmine-core/jasmine.css">
<script src="../node_modules/jasmine-core/lib/jasmine-core/jasmine.js"></script>
<script src="../node_modules/jasmine-core/lib/jasmine-core/jasmine-html.js"></script>
<script src="../node_modules/jasmine-core/lib/jasmine-core/boot.js"></script>
<script src="node_modules/zone.js/dist/zone.js"></script>
<script src="node_modules/reflect-metadata/Reflect.js"></script>
<script src="node_modules/systemjs/dist/system.src.js"></script>
<script src="systemjs.config.js"></script>
</head>
<body>
<!-- Unit Testing Chapter #1: Proof of life. -->
<script>
it('true is true', function(){ expect(true).toEqual(true); });
</script>
<script>
// #2. Configure systemjs to use the .js extension
// for imports from the app folder
System.config({defaultJSExtensions:true});
// #3. Load and configure the TestComponentBuilder.
// #2. Import the spec files explicitly
Promise.all([
System.import('app/literal.pipe.spec')
])
// #3. wait for all imports to load ...
// then re-execute `window.onload` which
// triggers the Jasmine test-runner start
// or explain what went wrong.
//System.import('app/literal.pipe.spec')
.then(window.onload)
.catch(console.error.bind(console));
</script>
</body>
</html>
literal.pipe.spec.ts如下：
import { By } from '@angular/platform-browser';
import { provide } from '@angular/core';
import { ViewMetadata } from '@angular/core';
import {LiteralPipe} from '../pipe/literal.pipe';
import {MessageService} from '../service/message.service';
import {Http} from '@angular/http';
import { TestBed } from '@angular/core/testing';
//import {BrowserDynamicTestingModule, platformBrowserDynamicTesting} from '@angular/platform-browser-dynamic/testing';
// TestBed.initTestEnvironment(
// BrowserDynamicTestingModule,
// platformBrowserDynamicTesting()
// );
let pipe: LiteralPipe;
let msgService: MessageService;
//////// SPECS /////////////
describe('LiteralPipe', () => {
beforeEach(()=>{
[addProviders([MessageService]) ]
});
TestBed.configureTestingModule({
declarations:[MessageService],
providers: [{provide:MessageService, useClass:MessageService } ],
imports: [MessageService, Http]
});
it('can get an instance', inject([MessageService], (msgService: MessageService) => {
//create instance of pipe using msgService as the instance of service.
pipe = new LiteralPipe(msgService);
}));
it('transforms "Home.title" to "Login"', () => {
expect(pipe.transform('Home.title', null)).toEqual('Login');
});
});
看起来我在spec文件的某个地方出错了，因为当我运行npm test并查看在浏览器中打开的unitTests时，我得到以下异常：
LiteralPipe can get an instance
TypeError: Cannot read property 'injector' of null
TypeError: Cannot read property 'injector' of null
at TestBed._createCompilerAndModule (http://localhost:3000/node_modules/@angular/core/testing/test_bed.js:246:44)
at TestBed._initIfNeeded (http://localhost:3000/node_modules/@angular/core/testing/test_bed.js:213:39)
at TestBed.execute (http://localhost:3000/node_modules/@angular/core/testing/test_bed.js:274:14)
at Object.eval (http://localhost:3000/node_modules/@angular/core/testing/test_bed.js:404:45)
at attemptSync (http://localhost:3000/node_modules/jasmine-core/lib/jasmine-core/jasmine.js:1886:24)
at QueueRunner.run (http://localhost:3000/node_modules/jasmine-core/lib/jasmine-core/jasmine.js:1874:9)
at QueueRunner.execute (http://localhost:3000/node_modules/jasmine-core/lib/jasmine-core/jasmine.js:1859:10)
at Spec.queueRunnerFactory (http://localhost:3000/node_modules/jasmine-core/lib/jasmine-core/jasmine.js:697:35)
at Spec.execute (http://localhost:3000/node_modules/jasmine-core/lib/jasmine-core/jasmine.js:359:10)
at Object.fn (http://localhost:3000/node_modules/jasmine-core/lib/jasmine-core/jasmine.js:2479:37)
LiteralPipe transforms "Home.title" to "Login"
TypeError: Cannot read property 'transform' of undefined
TypeError: Cannot read property 'transform' of undefined
at Object.eval (http://localhost:3000/app/literal.pipe.spec.js:30:20)
at attemptSync (http://localhost:3000/node_modules/jasmine-core/lib/jasmine-core/jasmine.js:1886:24)
我应该做些什么改变才能使这项工作。
答案 0 :(得分：4)
此处的问题是您正在错误地使用TeseBed。以下示例是literal.pipe.spec.ts文件的修改版本。
主要是你必须在初始化之前重置测试环境。
TestBed.resetTestEnvironment();
重置环境后，必须配置configureTestingModule：
TestBed
.initTestEnvironment(BrowserDynamicTestingModule, platformBrowserDynamicTesting())
.configureTestingModule({providers: [MessageService],imports: [HttpModule]});
import {By} from '@angular/platform-browser';
import {provide} from '@angular/core';
import {ViewMetadata} from '@angular/core';
import {LiteralPipe} from './pipe/literal.pipe';
import {MessageService} from '../services/message.service';
import {Http} from '@angular/http';
import {inject, TestBed} from '@angular/core/testing';
import {BrowserDynamicTestingModule, platformBrowserDynamicTesting} from "@angular/platform-browser-dynamic/testing";
import {HttpModule} from '@angular/http';
let pipe: LiteralPipe;
let msgService: MessageService;
//////// SPECS /////////////
describe('LiteralPipe', () => {
beforeEach(() => {
// Must reset the test environment before initializing it.
TestBed.resetTestEnvironment();
TestBed
.initTestEnvironment(BrowserDynamicTestingModule, platformBrowserDynamicTesting())
.configureTestingModule({
declarations: [],
providers: [
MessageService
],
imports: [
HttpModule
]
});
});
it('transforms "Home.title" to "Login"', inject([MessageService], (msgService: MessageService) => {
let pipe = new LiteralPipe(msgService);
expect(pipe.transform('Home.title', null)).toEqual('Login');
})
);
});
您的管道实现本身也存在问题。在尝试从中获取值之前，您应该检查args变量是否为null。
literal.pipe.ts
if(this.messageBundle[value])
return this.messageBundle[value];
else if(args != null && args[0])
return args;
else
return "String not available. Pls include in bundle.json";