gitlab-org--gitlab-foss/spec/javascripts/lazy_loader_spec.js

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JavaScript
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import LazyLoader from '~/lazy_loader';
import { TEST_HOST } from './test_constants';
import scrollIntoViewPromise from './helpers/scroll_into_view_promise';
import waitForPromises from './helpers/wait_for_promises';
import waitForAttributeChange from './helpers/wait_for_attribute_change';
const execImmediately = callback => {
callback();
};
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describe('LazyLoader', function() {
let lazyLoader = null;
preloadFixtures('issues/issue_with_comment.html.raw');
describe('without IntersectionObserver', () => {
beforeEach(function() {
loadFixtures('issues/issue_with_comment.html.raw');
lazyLoader = new LazyLoader({
observerNode: 'foobar',
});
spyOn(LazyLoader, 'supportsIntersectionObserver').and.callFake(() => false);
spyOn(LazyLoader, 'loadImage').and.callThrough();
spyOn(window, 'requestAnimationFrame').and.callFake(execImmediately);
spyOn(window, 'requestIdleCallback').and.callFake(execImmediately);
// Doing everything that happens normally in onload
lazyLoader.register();
});
afterEach(() => {
lazyLoader.unregister();
});
it('should copy value from data-src to src for img 1', function(done) {
const img = document.querySelectorAll('img[data-src]')[0];
const originalDataSrc = img.getAttribute('data-src');
Promise.all([scrollIntoViewPromise(img), waitForAttributeChange(img, ['data-src', 'src'])])
.then(() => {
expect(LazyLoader.loadImage).toHaveBeenCalled();
expect(img.getAttribute('src')).toBe(originalDataSrc);
expect(img).toHaveClass('js-lazy-loaded');
done();
})
.catch(done.fail);
});
it('should lazy load dynamically added data-src images', function(done) {
const newImg = document.createElement('img');
const testPath = `${TEST_HOST}/img/testimg.png`;
newImg.className = 'lazy';
newImg.setAttribute('data-src', testPath);
document.body.appendChild(newImg);
Promise.all([
scrollIntoViewPromise(newImg),
waitForAttributeChange(newImg, ['data-src', 'src']),
])
.then(() => {
expect(LazyLoader.loadImage).toHaveBeenCalled();
expect(newImg.getAttribute('src')).toBe(testPath);
expect(newImg).toHaveClass('js-lazy-loaded');
done();
})
.catch(done.fail);
});
it('should not alter normal images', function(done) {
const newImg = document.createElement('img');
const testPath = `${TEST_HOST}/img/testimg.png`;
newImg.setAttribute('src', testPath);
document.body.appendChild(newImg);
scrollIntoViewPromise(newImg)
.then(waitForPromises)
.then(() => {
expect(LazyLoader.loadImage).not.toHaveBeenCalled();
expect(newImg).not.toHaveClass('js-lazy-loaded');
done();
})
.catch(done.fail);
});
it('should not load dynamically added pictures if content observer is turned off', done => {
lazyLoader.stopContentObserver();
const newImg = document.createElement('img');
const testPath = `${TEST_HOST}/img/testimg.png`;
newImg.className = 'lazy';
newImg.setAttribute('data-src', testPath);
document.body.appendChild(newImg);
scrollIntoViewPromise(newImg)
.then(waitForPromises)
.then(() => {
expect(LazyLoader.loadImage).not.toHaveBeenCalled();
expect(newImg).not.toHaveClass('js-lazy-loaded');
done();
})
.catch(done.fail);
});
it('should load dynamically added pictures if content observer is turned off and on again', done => {
lazyLoader.stopContentObserver();
lazyLoader.startContentObserver();
const newImg = document.createElement('img');
const testPath = `${TEST_HOST}/img/testimg.png`;
newImg.className = 'lazy';
newImg.setAttribute('data-src', testPath);
document.body.appendChild(newImg);
Promise.all([
scrollIntoViewPromise(newImg),
waitForAttributeChange(newImg, ['data-src', 'src']),
])
.then(waitForPromises)
.then(() => {
expect(LazyLoader.loadImage).toHaveBeenCalled();
expect(newImg).toHaveClass('js-lazy-loaded');
done();
})
.catch(done.fail);
});
});
describe('with IntersectionObserver', () => {
beforeEach(function() {
loadFixtures('issues/issue_with_comment.html.raw');
lazyLoader = new LazyLoader({
observerNode: 'foobar',
});
spyOn(LazyLoader, 'loadImage').and.callThrough();
spyOn(window, 'requestAnimationFrame').and.callFake(execImmediately);
spyOn(window, 'requestIdleCallback').and.callFake(execImmediately);
// Doing everything that happens normally in onload
lazyLoader.register();
});
afterEach(() => {
lazyLoader.unregister();
});
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it('should copy value from data-src to src for img 1', function(done) {
const img = document.querySelectorAll('img[data-src]')[0];
const originalDataSrc = img.getAttribute('data-src');
Promise.all([scrollIntoViewPromise(img), waitForAttributeChange(img, ['data-src', 'src'])])
.then(() => {
expect(LazyLoader.loadImage).toHaveBeenCalled();
expect(img.getAttribute('src')).toBe(originalDataSrc);
expect(img).toHaveClass('js-lazy-loaded');
done();
})
.catch(done.fail);
});
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it('should lazy load dynamically added data-src images', function(done) {
const newImg = document.createElement('img');
const testPath = `${TEST_HOST}/img/testimg.png`;
newImg.className = 'lazy';
newImg.setAttribute('data-src', testPath);
document.body.appendChild(newImg);
Promise.all([
scrollIntoViewPromise(newImg),
waitForAttributeChange(newImg, ['data-src', 'src']),
])
.then(() => {
expect(LazyLoader.loadImage).toHaveBeenCalled();
expect(newImg.getAttribute('src')).toBe(testPath);
expect(newImg).toHaveClass('js-lazy-loaded');
done();
})
.catch(done.fail);
});
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it('should not alter normal images', function(done) {
const newImg = document.createElement('img');
const testPath = `${TEST_HOST}/img/testimg.png`;
newImg.setAttribute('src', testPath);
document.body.appendChild(newImg);
scrollIntoViewPromise(newImg)
.then(waitForPromises)
.then(() => {
expect(LazyLoader.loadImage).not.toHaveBeenCalled();
expect(newImg).not.toHaveClass('js-lazy-loaded');
done();
})
.catch(done.fail);
});
it('should not load dynamically added pictures if content observer is turned off', done => {
lazyLoader.stopContentObserver();
const newImg = document.createElement('img');
const testPath = `${TEST_HOST}/img/testimg.png`;
newImg.className = 'lazy';
newImg.setAttribute('data-src', testPath);
document.body.appendChild(newImg);
scrollIntoViewPromise(newImg)
.then(waitForPromises)
.then(() => {
expect(LazyLoader.loadImage).not.toHaveBeenCalled();
expect(newImg).not.toHaveClass('js-lazy-loaded');
done();
})
.catch(done.fail);
});
it('should load dynamically added pictures if content observer is turned off and on again', done => {
lazyLoader.stopContentObserver();
lazyLoader.startContentObserver();
const newImg = document.createElement('img');
const testPath = `${TEST_HOST}/img/testimg.png`;
newImg.className = 'lazy';
newImg.setAttribute('data-src', testPath);
document.body.appendChild(newImg);
Promise.all([
scrollIntoViewPromise(newImg),
waitForAttributeChange(newImg, ['data-src', 'src']),
])
.then(() => {
expect(LazyLoader.loadImage).toHaveBeenCalled();
expect(newImg).toHaveClass('js-lazy-loaded');
done();
})
.catch(done.fail);
});
});
});