angular 2 rc7 - testing service - Error: No provider for String - unit-testing

Question

I've getting an error in angular 2 testing using the webpack quickstart project.
Error: No provider for String! in config/karma-test-shim.js
I've never seen this error where the provider for String is missing. I figured out its related the private url:string in the services constructor but how do I resolve it?
Here's my testfile
describe('http.ts',()=>{
beforeEach(()=>{
TestBed.configureTestingModule({
providers:[
SbHttp,
MockBackend,
BaseRequestOptions,
{ provide: Http, useFactory: (backend: MockBackend, defaultOptions: BaseRequestOptions) => {
return new Http(backend, defaultOptions);
}, deps: [MockBackend, BaseRequestOptions]}
],
imports: [
HttpModule
]
})
});
afterEach(()=>{
TestBed.resetTestingModule()
});
it('get() should work', inject([SbHttp],(sbHttp:SbHttp)=>{
expect(true).toBeTruthy()
}))
})
and here's the SbHttp service
#Injectable()
export class SbHttp{
private baseUrl:string;
constructor( private url:string, private headers:Headers, private http:Http
){
this.baseUrl = utils.stripTrailingSlash(url)
}
}
If I change to private url:any I'm getting this error
Can't resolve all parameters for SbHttp: (?, Headers, Http).

Answer 1

You need to make it injectable by creating a token, using #Inject() to inject with the token, and then add it as a provider in the providers list .
import { OpaqueToken, Injct } from '#angular/core';
const APP_URL = new OpaqueToken('app.url');
class SbHttp {
constructor(#Inject(APP_URL) url: string, ...) {}
}
TestBed.configureTestingModule({
providers: [
{ provide: APP_URL, useValue: 'http://localhost' }
]
});
You'll also need to configure the providers in the real app also. As for the Headers, I'm not sure, but I think you might get the error also once you fix this one. I'm not sure where you expect to be getting that from.
I highly suggest you take a look at the dependency injection chapter from the Angular documentation if you are new to DI with Angular.