@superset-ui/core
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JavaScript
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
import { renderHook } from '@testing-library/react-hooks';
import { useElementOnScreen } from './useElementOnScreen';
const observeMock = jest.fn();
const unobserveMock = jest.fn();
const IntersectionObserverMock = jest.fn();
IntersectionObserverMock.prototype.observe = observeMock;
IntersectionObserverMock.prototype.unobserve = unobserveMock;
beforeEach(() => {
window.IntersectionObserver = IntersectionObserverMock;
});
afterEach(() => {
IntersectionObserverMock.mockClear();
jest.clearAllMocks();
});
test('should return null and false on first render', () => {
const hook = renderHook(() => useElementOnScreen({ rootMargin: '-50px 0px 0px 0px' }));
expect(hook.result.current).toEqual([{ current: null }, false]);
});
test('should return isSticky as true when intersectionRatio < 1', async () => {
const hook = renderHook(() => useElementOnScreen({ rootMargin: '-50px 0px 0px 0px' }));
const callback = IntersectionObserverMock.mock.calls[0][0];
const callBack = callback([{ isIntersecting: true, intersectionRatio: 0.5 }]);
const observer = new IntersectionObserverMock(callBack, {});
const newDiv = document.createElement('div');
observer.observe(newDiv);
expect(hook.result.current[1]).toEqual(true);
});
test('should return isSticky as false when intersectionRatio >= 1', async () => {
const hook = renderHook(() => useElementOnScreen({ rootMargin: '-50px 0px 0px 0px' }));
const callback = IntersectionObserverMock.mock.calls[0][0];
const callBack = callback([{ isIntersecting: true, intersectionRatio: 1 }]);
const observer = new IntersectionObserverMock(callBack, {});
const newDiv = document.createElement('div');
observer.observe(newDiv);
expect(hook.result.current[1]).toEqual(false);
});
test('should observe and unobserve element with IntersectionObserver', async () => {
jest.spyOn(global.React, 'useRef').mockReturnValue({ current: 'test' });
const options = { threshold: 0.5 };
const { result, unmount } = renderHook(() => useElementOnScreen(options));
const [elementRef] = result.current;
expect(IntersectionObserverMock).toHaveBeenCalledWith(expect.any(Function), options);
expect(elementRef).not.toBe(null);
expect(observeMock).toHaveBeenCalledWith(elementRef.current);
unmount();
expect(unobserveMock).toHaveBeenCalledWith(elementRef.current);
});
test('should not observe an element if it is null', () => {
jest.spyOn(global.React, 'useRef').mockReturnValue({ current: null });
const options = {};
const { result } = renderHook(() => useElementOnScreen(options));
const [ref, isSticky] = result.current;
expect(ref.current).toBe(null);
expect(isSticky).toBe(false);
expect(observeMock).not.toHaveBeenCalled();
});
test('should not unobserve the element if it is null', () => {
jest.spyOn(global.React, 'useRef').mockReturnValue({ current: null });
const options = {};
const { result, unmount } = renderHook(() => useElementOnScreen(options));
const [ref, isSticky] = result.current;
expect(ref.current).toBe(null);
expect(isSticky).toBe(false);
unmount();
expect(unobserveMock).not.toHaveBeenCalled();
});
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