I am trying to write unit tests for my API service but have some trouble catching HTTP errors. I am following this guide along with the Angular2 docs since the guide is (slightly) out of date in some minor areas.

All unit tests pass apart from those where an error is thrown by the service (due to error HTTP status code). I can tell this by logging out response.ok. From what i've read this has something to do with the unit tests not executing asynchronously, hence, not waiting for the error response. However, I have no idea why this is the case here since I have used the async() utility function in the beforeEach method.

API Service

get(endpoint: string, authenticated: boolean = false): Observable<any> {
    endpoint = this.formatEndpoint(endpoint);
    return this.getHttp(authenticated) // Returns @angular/http or a wrapper for handling auth headers
        .get(endpoint)
        .map(res => this.extractData(res))
        .catch(err => this.handleError(err)); // Not in guide but should work as per docs
}
private extractData(res: Response): any {
    let body: any = res.json();
    return body || { };
}

private handleError(error: Response | any): Observable<any> {
    // TODO: Use a remote logging infrastructure
    // TODO: User error notifications
    let errMsg: string;
    if (error instanceof Response) {
        const body: any = error.json() || '';
        const err: string = body.error || JSON.stringify(body);
        errMsg = `${error.status} - ${error.statusText || ''}${err}`;
    } else {
        errMsg = error.message ? error.message : error.toString();
    }
    console.error(errMsg);
    return Observable.throw(errMsg);
}

Error unit test

// Imports

describe('Service: APIService', () => {
    let backend: MockBackend;
    let service: APIService;

    beforeEach(async(() => {
        TestBed.configureTestingModule({
            providers: [
                BaseRequestOptions,
                MockBackend,
                APIService,
                {
                    deps: [
                        MockBackend,
                        BaseRequestOptions
                    ],
                    provide: Http,
                        useFactory: (backend: XHRBackend, defaultOptions: BaseRequestOptions) => {
                            return new Http(backend, defaultOptions);
                        }
                },
                {provide: AuthHttp,
                    useFactory: (http: Http, options: BaseRequestOptions) => {
                        return new AuthHttp(new AuthConfig({}), http, options);
                    },
                    deps: [Http, BaseRequestOptions]
                }
            ]
        });
        const testbed: any = getTestBed();
        backend = testbed.get(MockBackend);
        service = testbed.get(APIService);
    }));

    /**
     * Utility function to setup the mock connection with the required options
     * @param backend
     * @param options
     */
    function setupConnections(backend: MockBackend, options: any): any {
        backend.connections.subscribe((connection: MockConnection) => {
            const responseOptions: any = new ResponseOptions(options);
            const response: any = new Response(responseOptions);
            console.log(response.ok); // Will return false during the error unit test and true in others (if spyOn log is commented).
            connection.mockRespond(response);
        });
    }

    it('should log an error to the console on error', () => {
        setupConnections(backend, {
            body: { error: `Some strange error` },
            status: 400
        });
        spyOn(console, 'error');
        spyOn(console, 'log');

        service.get('/bad').subscribe(null, e => {
            // None of this code block is executed.
            expect(console.error).toHaveBeenCalledWith("400 - Some strange error");
            console.log("Make sure an error has been thrown");
        });

        expect(console.log).toHaveBeenCalledWith("Make sure an error has been thrown."); // Fails
    });

Update 1

when I check the first callback, response.ok is undefined. This leads me to believe that there is something wrong in the setupConnections utility.

    it('should log an error to the console on error', async(() => {
        setupConnections(backend, {
            body: { error: `Some strange error` },
            status: 400
        });
        spyOn(console, 'error');
        //spyOn(console, 'log');

        service.get('/bad').subscribe(res => {
            console.log(res); // Object{error: 'Some strange error'}
            console.log(res.ok); // undefined
        }, e => {
            expect(console.error).toHaveBeenCalledWith("400 - Some strange error");
            console.log("Make sure an error has been thrown");
        });

        expect(console.log).toHaveBeenCalledWith("Make sure an error has been thrown.");
    }));

Update 2

If, instead of catching errors in the get method I do it explicitly in map then still have same problem.

get(endpoint: string, authenticated: boolean = false): Observable<any> {
    endpoint = this.formatEndpoint(endpoint);
    return this.getHttp(authenticated).get(endpoint)
        .map(res => {
            if (res.ok) return this.extractData(res);
            return this.handleError(res);
        })
        .catch(this.handleError);
}

Update 3

After some discussion this issue submitted