Does someone knows how can I test this function in Jest? I don't have any ideas at this moment, maybe I need to mock Cookies ?
import Cookies from "js-cookie";
import { v4 as uuidv4 } from "uuid";
const setUserCookie = () => {
if (!Cookies.get("UserToken")) {
Cookies.set("UserToken", uuidv4(), { expires: 10 });
}
};
export default setUserCookie;
I tried this for now, but I don't know if this is correct, I don't think it tests the functionality of my function:
import Cookies from 'js-cookie';
import setCookie from './setCookie';
describe("setCookie", () => {
it("should set cookie", () => {
const mockSet = jest.fn();
Cookies.set = mockSet;
Cookies.set('testCookie', 'testValue');
setCookie()
expect(mockSet).toBeCalled();
});
});
Best way to test this is to utilize the actual logic, so I would change your test to the following:
it("should set cookie", () => {
// execute actual logic
setCookie();
// retrieve the result
const resultCookie = Cookies.get();
// expects here
expect(resultCookie["UserToken"]).toBeTruthy();
// expects for other values here...
});
To note, uuidv4() will generate a new value for every new test run, meaning that you cannot expect the same value for the "UserToken" property. Instead, you can use the following approach to tackle this problem:
First set up a spy for it:
import { v4 as uuidv4 } from "uuid";
jest.mock('uuid');
Then add its mock implementation with the expected result into the unit test:
const expectedUUIDV4 = 'testId';
uuidv4.mockImplementation(() => expectedUUIDV4);
// then expecting that in the result
expect(resultCookie["UserToken"]).toEqual(expectedUUIDV4);