test broke when changed model with interfaces to classes - json

Question

Sorry if its a bit long but I wanted to explain myself well.
I have a test for an api call im performing from my service to receive a simple json. (Karma-jasmin/angular2)
this is the call from my service:
#Injectable()
export class MyService {
constructor(private _myApiService:MyAPIService) {
}
public getCarsData():Observable<Car[]> {
return this._myApiService.getCurrentCarData().map(res => res.carList);
}
}
this is getCurrentCarData():
export interface CarsListResponse extends ServerResponse {
carList: Cars[];
}
public getCurrentCarData(): Observable<CarsListResponse> {
let apiURL = 'my/api/url'
return this.http.get(apiURL),
(ret, retJson) => ret.status === 200 ? {carList: retJson.cars.map(element => new Car(element.year, element.make))} : undefined);
}
Car interface is:
export interface Car {
make:string;
year:number;
}
the json Im getting looks like this (part of a mock):
status: 200,
headers: new Headers(HEADERS),
body: {
cars: [
{
"make": "Mercedes",
"year": 2016
},
{
"make": "Audi",
"year": 2017
},
{
"make": "BMW",
"year": 2015
}
]
}
Test: the test is for getCurrentCarData():
let carsResponse = () => {
return { cars: [
{
"make": "Mercedes",
"year": 2016
},
{
"make": "Audi",
"year": 2017
},
{
"make": "BMW",
"year": 2015
}
]}
};
let carsExpectedResponse = () => {
return [
{
"make": "Mercedes",
"year": 2016
},
{
"make": "Audi",
"year": 2017
},
{
"make": "BMW",
"year": 2015
}
]
};
describe('GET Car Data', () => {
it('should handle respond', inject([XHRBackend, api.MyApiService], (mock, myApiService) => {
let c:Connection = null;
mock.connections.subscribe((connection) => {
connection.mock(new Response(new ResponseOptions({
status: 200,
headers: jsoHeaders(),
body: carsResponse()
})));
c = connection;
});
myApiService.getCurrentCarData().subscribe(
res => {
expect(c.request.url).toEqual(`my/api/url`);
expect(res.carList).toEqual(carsExpectedResponse());
},
error => {
expect(false).toBeTruthy();
}
);
}));
});
Ok, so this works! THE problem is when I changed my model from this
interface:
export interface Car {
make:string;
year:number;
}
to this class:
export class Car implements GenType {
make:string;
year:number;
constructor(make:string, year:number) {
this.make = make;
this.year = year;
}
displayFormat:() => string = function () {
return 'someStr'
}
}
export interface GenType {
displayFormat: () => string;
}
so now the error im getting is:
Expected
[MatcherEntityBulk({ displayFormat: Function, make: 'Mercedes', year: 2016 }),
MatcherEntityBulk({ displayFormat: Function, make: 'Audi', year: 2017 }),
MatcherEntityBulk({ displayFormat: Function, make: 'BMW', year: 2015 })]
to equal
[Object({ displayFormat: Function, make: 'Mercedes', year: 2016 }),
Object({ displayFormat: Function, make: 'Audi', year: 2017 }),
Object({ displayFormat: Function, make: 'BMW', year: 2015 })]
So the problem is pretty obvious, but how do I fix this, I mean with the current change what would be a proper way to change that test?
thanks a bunch for the ones that survived to this point :)

Answer 1

toEqual expects carsExpectedResponse() array elements to be instances of certain class (for example, Car). It tests object constructors and expects them to have non-enumerable property constructor that contains a constructor.
It can be a real instance:
let carsExpectedResponse = () => [
new Car(...),
...
];
It can be a fake non-enumerable constructor property:
let carsExpectedResponse = () => [
{
"make": "Mercedes",
"year": 2016
},
...
].map(obj => Object.defineProperty(obj, 'constructor', { value: Car }));
It can be an object constructed with desired prototype chain:
let carsExpectedResponse = () => [
{
"make": "Mercedes",
"year": 2016
},
...
].map(obj => Object.assign(Object.create(Car.prototype), obj));
The last fixture object is probably the most solid, because it doesn't depend on Jasmine internal logic and doesn't depend on constructor logic, too.