astro/packages/integrations/mdx/test/mdx-frontmatter-injection.test.js

import { expect } from 'chai';
import { parseHTML } from 'linkedom';
import { loadFixture } from '../../../astro/test/test-utils.js';

const FIXTURE_ROOT = new URL('./fixtures/mdx-frontmatter-injection/', import.meta.url);

describe('MDX frontmatter injection', () => {
	let fixture;

	before(async () => {
		fixture = await loadFixture({
			root: FIXTURE_ROOT,
		});
		await fixture.build();
	});

	it('remark supports custom vfile data - get title', async () => {
		const frontmatterByPage = JSON.parse(await fixture.readFile('/glob.json'));
		const titles = frontmatterByPage.map((frontmatter = {}) => frontmatter.title);
		expect(titles).to.contain('Page 1');
		expect(titles).to.contain('Page 2');
	});

	it('rehype supports custom vfile data - reading time', async () => {
		const frontmatterByPage = JSON.parse(await fixture.readFile('/glob.json'));
		const readingTimes = frontmatterByPage.map(
			(frontmatter = {}) => frontmatter.injectedReadingTime
		);
		expect(readingTimes.length).to.be.greaterThan(0);
		for (let readingTime of readingTimes) {
			expect(readingTime).to.not.be.null;
			expect(readingTime.text).match(/^\d+ min read/);
		}
	});

	it('overrides injected frontmatter with user frontmatter', async () => {
		const frontmatterByPage = JSON.parse(await fixture.readFile('/glob.json'));
		const readingTimes = frontmatterByPage.map(
			(frontmatter = {}) => frontmatter.injectedReadingTime?.text
		);
		const titles = frontmatterByPage.map((frontmatter = {}) => frontmatter.title);
		expect(titles).to.contain('Overridden title');
		expect(readingTimes).to.contain('1000 min read');
	});

	it('passes injected frontmatter to layouts', async () => {
		const html1 = await fixture.readFile('/page-1/index.html');
		const html2 = await fixture.readFile('/page-2/index.html');

		const title1 = parseHTML(html1).document.querySelector('title');
		const title2 = parseHTML(html2).document.querySelector('title');

		expect(title1.innerHTML).to.equal('Page 1');
		expect(title2.innerHTML).to.equal('Page 2');
	});
});