Typescript + jasmine.createSpy()

Question

I'm writing unit tests for my angular project with Typescript

When I try to create mock for some service, I use this way:

const serviceMock = <IMyService>{
    method: _.noop,
};

beforeEach(inject($injector => {
   testingService = new AccountingService(serviceMock);

   spyOn(serviceMock, 'method').and.callFake(()=>'hello');
 }

this works ok but when I try to use jasmine.createSpy(), I get compilation errors:

const serviceMock = <IMyService>{
    method: jasmine.createSpy('method').and.callFake(()=>'hello'),
};

Type '{ method: Spy;}' cannot be converted to type 'MyService'. Property 'getParams' is missing in type '{ method: Spy;}'.

But getParams is private method of MyService

What am I doing wrong?

Answer 1

Use the type already defined and used by Jasmine SpyObj<T>.

const serviceMock: jasmine.SpyObj<IMyService> = jasmine.createSpyObj<IMyService>('service',['method']);

This way every method of IMyService will be augmented with the Spy ones:

serviceMock.method.and.callFake(()=>'hello');