Help me please internetz

psu.js

export const setPanelLoading = elm => {
    elm.classList.add('is-loading');
};

export const setPanelLoaded = elm => {
    elm.classList.remove('is-loading');
};

export const panelStatusUpdater = (container, promiseToAwait, timeout = 300) => {
    const deferredOverlay = setTimeout(() => {
        setPanelLoading(container);
    }, timeout);

    return promiseToAwait;
        .finally(data => {
            clearTimeout(deferredOverlay);
            setPanelLoaded(container);
            return data;
        });
};

psu.test.js

import * as PSU from '../src/utils/panel-status-updater';

//jest.useFakeTimers();

describe('panel status updater', () => {
    
    describe('setPanelLoading', () => {
        it('should add `is-loading` class to target element', () => {
            const target = document.createElement("div");
            PSU.setPanelLoading(target);
            expect(target.classList.contains("is-loading")).toBeTruthy();
        });
    });

    describe('setPanelLoaded', () => {
        it('should remove `is-loading` class to target element', () => {
            const target = document.createElement("div");
            target.class = "is-loading";
            PSU.setPanelLoaded(target);
            expect(target.classList.contains("is-loading")).toBeFalsy();
        });
    });

    describe('panelStatusUpdater', () => {
        it('should call `setPanelLoading` internally after a timeout', (done) => {
            PSU.setPanelLoading = jest.fn();

            const target = document.createElement("div");
            const testPromise = new Promise(resolve => {
                setTimeout(() => {
                    resolve("data");
                }, 2);
            });

            const results = PSU.panelStatusUpdater(target, testPromise, 1)
                .then(data => {
                    console.log(PSU.setPanelLoading);
                    console.log(PSU.setPanelLoading.mock.calls.length);

                    expect(data).toBe("data");
                    done();
                })
        });
    });
});