1 files changed, 189 insertions, 0 deletions
diff --git a/packages/markdown/remark/test/frontmatter.test.js b/packages/markdown/remark/test/frontmatter.test.js
new file mode 100644
index 000000000..336245106
--- /dev/null
+++ b/packages/markdown/remark/test/frontmatter.test.js
@@ -0,0 +1,189 @@
+import assert from 'node:assert/strict';
+import { describe, it } from 'node:test';
+import { extractFrontmatter, parseFrontmatter } from '../dist/index.js';
+
+const bom = '\uFEFF';
+
+describe('extractFrontmatter', () => {
+	it('handles YAML', () => {
+		const yaml = `\nfoo: bar\n`;
+		assert.equal(extractFrontmatter(`---${yaml}---`), yaml);
+		assert.equal(extractFrontmatter(`${bom}---${yaml}---`), yaml);
+		assert.equal(extractFrontmatter(`\n---${yaml}---`), yaml);
+		assert.equal(extractFrontmatter(`\n  \n---${yaml}---`), yaml);
+		assert.equal(extractFrontmatter(`---${yaml}---\ncontent`), yaml);
+		assert.equal(extractFrontmatter(`${bom}---${yaml}---\ncontent`), yaml);
+		assert.equal(extractFrontmatter(`\n\n---${yaml}---\n\ncontent`), yaml);
+		assert.equal(extractFrontmatter(`\n  \n---${yaml}---\n\ncontent`), yaml);
+		assert.equal(extractFrontmatter(` ---${yaml}---`), undefined);
+		assert.equal(extractFrontmatter(`---${yaml} ---`), undefined);
+		assert.equal(extractFrontmatter(`text\n---${yaml}---\n\ncontent`), undefined);
+	});
+
+	it('handles TOML', () => {
+		const toml = `\nfoo = "bar"\n`;
+		assert.equal(extractFrontmatter(`+++${toml}+++`), toml);
+		assert.equal(extractFrontmatter(`${bom}+++${toml}+++`), toml);
+		assert.equal(extractFrontmatter(`\n+++${toml}+++`), toml);
+		assert.equal(extractFrontmatter(`\n  \n+++${toml}+++`), toml);
+		assert.equal(extractFrontmatter(`+++${toml}+++\ncontent`), toml);
+		assert.equal(extractFrontmatter(`${bom}+++${toml}+++\ncontent`), toml);
+		assert.equal(extractFrontmatter(`\n\n+++${toml}+++\n\ncontent`), toml);
+		assert.equal(extractFrontmatter(`\n  \n+++${toml}+++\n\ncontent`), toml);
+		assert.equal(extractFrontmatter(` +++${toml}+++`), undefined);
+		assert.equal(extractFrontmatter(`+++${toml} +++`), undefined);
+		assert.equal(extractFrontmatter(`text\n+++${toml}+++\n\ncontent`), undefined);
+	});
+});
+
+describe('parseFrontmatter', () => {
+	it('works for YAML', () => {
+		const yaml = `\nfoo: bar\n`;
+		assert.deepEqual(parseFrontmatter(`---${yaml}---`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: yaml,
+			content: '',
+		});
+		assert.deepEqual(parseFrontmatter(`${bom}---${yaml}---`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: yaml,
+			content: bom,
+		});
+		assert.deepEqual(parseFrontmatter(`\n---${yaml}---`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: yaml,
+			content: '\n',
+		});
+		assert.deepEqual(parseFrontmatter(`\n  \n---${yaml}---`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: yaml,
+			content: '\n  \n',
+		});
+		assert.deepEqual(parseFrontmatter(`---${yaml}---\ncontent`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: yaml,
+			content: '\ncontent',
+		});
+		assert.deepEqual(parseFrontmatter(`${bom}---${yaml}---\ncontent`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: yaml,
+			content: `${bom}\ncontent`,
+		});
+		assert.deepEqual(parseFrontmatter(`\n\n---${yaml}---\n\ncontent`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: yaml,
+			content: '\n\n\n\ncontent',
+		});
+		assert.deepEqual(parseFrontmatter(`\n  \n---${yaml}---\n\ncontent`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: yaml,
+			content: '\n  \n\n\ncontent',
+		});
+		assert.deepEqual(parseFrontmatter(` ---${yaml}---`), {
+			frontmatter: {},
+			rawFrontmatter: '',
+			content: ` ---${yaml}---`,
+		});
+		assert.deepEqual(parseFrontmatter(`---${yaml} ---`), {
+			frontmatter: {},
+			rawFrontmatter: '',
+			content: `---${yaml} ---`,
+		});
+		assert.deepEqual(parseFrontmatter(`text\n---${yaml}---\n\ncontent`), {
+			frontmatter: {},
+			rawFrontmatter: '',
+			content: `text\n---${yaml}---\n\ncontent`,
+		});
+	});
+
+	it('works for TOML', () => {
+		const toml = `\nfoo = "bar"\n`;
+		assert.deepEqual(parseFrontmatter(`+++${toml}+++`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: toml,
+			content: '',
+		});
+		assert.deepEqual(parseFrontmatter(`${bom}+++${toml}+++`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: toml,
+			content: bom,
+		});
+		assert.deepEqual(parseFrontmatter(`\n+++${toml}+++`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: toml,
+			content: '\n',
+		});
+		assert.deepEqual(parseFrontmatter(`\n  \n+++${toml}+++`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: toml,
+			content: '\n  \n',
+		});
+		assert.deepEqual(parseFrontmatter(`+++${toml}+++\ncontent`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: toml,
+			content: '\ncontent',
+		});
+		assert.deepEqual(parseFrontmatter(`${bom}+++${toml}+++\ncontent`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: toml,
+			content: `${bom}\ncontent`,
+		});
+		assert.deepEqual(parseFrontmatter(`\n\n+++${toml}+++\n\ncontent`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: toml,
+			content: '\n\n\n\ncontent',
+		});
+		assert.deepEqual(parseFrontmatter(`\n  \n+++${toml}+++\n\ncontent`), {
+			frontmatter: { foo: 'bar' },
+			rawFrontmatter: toml,
+			content: '\n  \n\n\ncontent',
+		});
+		assert.deepEqual(parseFrontmatter(` +++${toml}+++`), {
+			frontmatter: {},
+			rawFrontmatter: '',
+			content: ` +++${toml}+++`,
+		});
+		assert.deepEqual(parseFrontmatter(`+++${toml} +++`), {
+			frontmatter: {},
+			rawFrontmatter: '',
+			content: `+++${toml} +++`,
+		});
+		assert.deepEqual(parseFrontmatter(`text\n+++${toml}+++\n\ncontent`), {
+			frontmatter: {},
+			rawFrontmatter: '',
+			content: `text\n+++${toml}+++\n\ncontent`,
+		});
+	});
+
+	it('frontmatter style for YAML', () => {
+		const yaml = `\nfoo: bar\n`;
+		const parse1 = (style) => parseFrontmatter(`---${yaml}---`, { frontmatter: style }).content;
+		assert.deepEqual(parse1('preserve'), `---${yaml}---`);
+		assert.deepEqual(parse1('remove'), '');
+		assert.deepEqual(parse1('empty-with-spaces'), `   \n        \n   `);
+		assert.deepEqual(parse1('empty-with-lines'), `\n\n`);
+
+		const parse2 = (style) =>
+			parseFrontmatter(`\n  \n---${yaml}---\n\ncontent`, { frontmatter: style }).content;
+		assert.deepEqual(parse2('preserve'), `\n  \n---${yaml}---\n\ncontent`);
+		assert.deepEqual(parse2('remove'), '\n  \n\n\ncontent');
+		assert.deepEqual(parse2('empty-with-spaces'), `\n  \n   \n        \n   \n\ncontent`);
+		assert.deepEqual(parse2('empty-with-lines'), `\n  \n\n\n\n\ncontent`);
+	});
+
+	it('frontmatter style for TOML', () => {
+		const toml = `\nfoo = "bar"\n`;
+		const parse1 = (style) => parseFrontmatter(`+++${toml}+++`, { frontmatter: style }).content;
+		assert.deepEqual(parse1('preserve'), `+++${toml}+++`);
+		assert.deepEqual(parse1('remove'), '');
+		assert.deepEqual(parse1('empty-with-spaces'), `   \n           \n   `);
+		assert.deepEqual(parse1('empty-with-lines'), `\n\n`);
+
+		const parse2 = (style) =>
+			parseFrontmatter(`\n  \n+++${toml}+++\n\ncontent`, { frontmatter: style }).content;
+		assert.deepEqual(parse2('preserve'), `\n  \n+++${toml}+++\n\ncontent`);
+		assert.deepEqual(parse2('remove'), '\n  \n\n\ncontent');
+		assert.deepEqual(parse2('empty-with-spaces'), `\n  \n   \n           \n   \n\ncontent`);
+		assert.deepEqual(parse2('empty-with-lines'), `\n  \n\n\n\n\ncontent`);
+	});
+});