how to mock http error for angular2 testing

Question

I am writing unit tests for an angular2 service. Code snippets:

// jasmine specfile

// already injected MockConnection into Http

backend.connections.subscribe ((c: MockConnection) => {
    connection = c;
});

// doing get-request
myServiceCallwithHttpRequest ().subscribe (result => {
    // this test passes!
    expect (result).toEqual ({
        "message": "No Such Object"
    });
    // this test fails, don't know how to get the response code
    expect (whereIsResponseStatus).toBe (404);
});

connection.mockRespond (new Response (new ResponseOptions ({
    body: {
        "message": "No Such Object"
    },
    status: 404
})));

my Service:

// service

myServiceCallwithHttpRequest (): Observable<Response> {
    return this.http.get ('/my/json-service').map (res => {
            // res.status == null
            return res.json ()
        })
        .catch (this.handleError); // from angular2 tutorial
}

The first expect is OK, the program goes into the map call, not the catch. But how do I get the status code 404? res.status is null.

Answer 1

To get the mock error working, you need to import ResponseType from @angular/http and include the error type in the mock response, then extend Response and implement Error

import { Response, ResponseOptions, ResponseType, Request } from '@angular/http';
import { MockConnection } from '@angular/http/testing';

class MockError extends Response implements Error {
    name:any
    message:any
}

...
handleConnection(connection:MockConnection) {
    let body = JSON.stringify({key:'val'});
    let opts = {type:ResponseType.Error, status:404, body: body};
    let responseOpts = new ResponseOptions(opts);
    connection.mockError(new MockError(responseOpts));
}

Answer 2

Going over the source code at node_modules\\@angular\\http\\testing\\mock_backend.d.ts . MockConnection.mockRespond is already in your code. MockConnection.mockError is what you may need. Play with it and see what you get.

Answer 3

You need to use .subscribe over the observable to register success , error & completed callback

Code

myServiceCallwithHttpRequest (): Observable<Response> {
    return this.http.get ('/my/json-service').map (res => {
            // res.status == null
            return res.json ()
        })
        .subscribe(
            data => this.saveJwt(data.id_token), //success
            err => { //error function
               //error object will have status of request.
               console.log(err);
            }, 
            () => console.log('Authentication Complete') //completed
        );
        //.catch (this.handleError); // from angular2 tutorial
}

Answer 4

works for me:

    mockConnection.mockRespond (new Response (new ResponseOptions ({
        body: {},
        status: 404
    })));