Jasmine - undefined is not a constructor

Question

export default {
  retrieve() {...},
  process: {
    getData(source) {
      return this.retrieve({id: source.id})
         .then((reply) => {
              source.reply = reply;
              return reply
          });
   }
 }
}

Test

describe("getData", () => {
    const source = { id: 1 };
    it("calls #retrieve", () => {
        spyOn(helpers, "retrieve").and.returnValue(PromiseSpy);
        helpers.process.getData(source);
        expect(helpers.retrieve).toHaveBeenCalled();
    });
});

Error: undefined is not a constructor evaluating this.retrieve({id: source.id}).

Can anyone help with what I might be doing wrong?

I think you might want to change `returnValue` for `callThrough()` returnValue wont actually call the function — Orangel Marquez, Mar 02 '20 at 01:24
`helpers.process.getData()` already seems incorrect – `this` will be `helpers.process`, not `helpers`, so `this.retrieve()` won’t exist. — Ry-, Mar 02 '20 at 02:56

score 0 · Answer 1 · answered Mar 02 '20 at 02:53

I have added a working example in stackblitz so you can play with it. If you want to mock a function you can use "and.callFake" in Jasmine.

spyOn(helpers, "fetch").and.callFake(
      () => new Promise((resolve, reject) => resolve({data: "mocked"}))
    );
const data = await helpers.getList(1);
expect(data).toBe("mocked");

Here is the link to stackblitz. https://stackblitz.com/edit/jasmine-testing-c2nicd?file=src%2Fhelpers.spec.ts

Jasmine - undefined is not a constructor

1 Answers1