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import { addClassIfElementExists, canScrollUp, canScrollDown } from '~/lib/utils/dom_utils';
const TEST_MARGIN = 5;
describe('DOM Utils', () => {
describe('addClassIfElementExists', () => {
const className = 'biology';
const fixture = `
<div class="parent">
<div class="child"></div>
</div>
`;
let parentElement;
beforeEach(() => {
setFixtures(fixture);
parentElement = document.querySelector('.parent');
});
it('adds class if element exists', () => {
const childElement = parentElement.querySelector('.child');
expect(childElement).not.toBe(null);
addClassIfElementExists(childElement, className);
expect(childElement.classList).toContainEqual(className);
});
it('does not throw if element does not exist', () => {
const childElement = parentElement.querySelector('.other-child');
expect(childElement).toBe(null);
addClassIfElementExists(childElement, className);
});
});
describe('canScrollUp', () => {
[1, 100].forEach(scrollTop => {
it(`is true if scrollTop is > 0 (${scrollTop})`, () => {
expect(
canScrollUp({
scrollTop,
}),
).toBe(true);
});
});
[0, -10].forEach(scrollTop => {
it(`is false if scrollTop is <= 0 (${scrollTop})`, () => {
expect(
canScrollUp({
scrollTop,
}),
).toBe(false);
});
});
it('is true if scrollTop is > margin', () => {
expect(
canScrollUp(
{
scrollTop: TEST_MARGIN + 1,
},
TEST_MARGIN,
),
).toBe(true);
});
it('is false if scrollTop is <= margin', () => {
expect(
canScrollUp(
{
scrollTop: TEST_MARGIN,
},
TEST_MARGIN,
),
).toBe(false);
});
});
describe('canScrollDown', () => {
let element;
beforeEach(() => {
element = {
scrollTop: 7,
offsetHeight: 22,
scrollHeight: 30,
};
});
it('is true if element can be scrolled down', () => {
expect(canScrollDown(element)).toBe(true);
});
it('is false if element cannot be scrolled down', () => {
element.scrollHeight -= 1;
expect(canScrollDown(element)).toBe(false);
});
it('is true if element can be scrolled down, with margin given', () => {
element.scrollHeight += TEST_MARGIN;
expect(canScrollDown(element, TEST_MARGIN)).toBe(true);
});
it('is false if element cannot be scrolled down, with margin given', () => {
expect(canScrollDown(element, TEST_MARGIN)).toBe(false);
});
});
});
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