@exadel/esl/modules/esl-utils/test/intersectionObserver.mock.js

Exadel Smart Library (ESL) is the lightweight custom elements library that provide a set of super-flexible components

import { ESLEventUtils } from '../../esl-event-listener/core/api';
import { wrap } from '../misc/array';
import { Rect } from '../dom/rect';
let original;
let lastMock;
export class RectMock extends Rect {
    constructor(...args) {
        if (args.length === 0)
            super(0, 0, 0, 0);
        else
            super(...args);
    }
    toJSON() {
        return this;
    }
}
export class IntersectionObserverMock {
    constructor(callback) {
        this.callback = callback;
        this.root = null;
        this.rootMargin = '';
        this._onObserve = this._onObserve.bind(this);
        this.observe = jest.fn(this.observe);
        this.unobserve = jest.fn(this.unobserve);
        this.disconnect = jest.fn(this.disconnect);
    }
    get thresholds() {
        return [];
    }
    takeRecords() {
        return [];
    }
    _onObserve(e) {
        const entries = wrap(e.detail).map((entry) => IntersectionObserverMock.createEntry(e.target, entry));
        this.callback(entries, this);
    }
    observe(element) {
        element.addEventListener('intersection', this._onObserve);
    }
    unobserve(element) {
        element.removeEventListener('intersection', this._onObserve);
    }
    disconnect() { }
    static createEntry(target, init) {
        const intersectionRatio = init.intersectionRatio || 0;
        return Object.assign({ 
            // Defaults
            target, intersectionRect: new RectMock(0, 0, 2000, 2000 * intersectionRatio), rootBounds: new RectMock(0, 0, 2000, 2000), boundingClientRect: new RectMock(0, 0, 2000, 2000), isIntersecting: false, intersectionRatio: 0, time: Date.now() }, init);
    }
    static trigger($el, detail) {
        ESLEventUtils.dispatch($el, 'intersection', { detail });
    }
    static mock() {
        original = window.IntersectionObserver;
        window.IntersectionObserver = jest.fn((cb) => (lastMock = new IntersectionObserverMock(cb)));
    }
    static unmock() {
        window.IntersectionObserver = original;
    }
    static get lastInstance() {
        return lastMock;
    }
}