Improve Markdown + Components usage (#3410)

* feat: use internal MDX tooling for markdown + components

* fix: improve MD + component tests

* chore: add changeset

* fix: make tsc happy

* fix(#3319): add regression test for component children

* fix(markdown): support HTML comments in markdown

* fix(#2474): ensure namespaced components are properly handled in markdown pages

* fix(#3220): ensure html in markdown pages does not have extra surrounding space

* fix(#3264): ensure that remark files pass in file information

* fix(#3254): enable experimentalStaticExtraction for `.md` pages

* fix: revert parsing change

* fix: remove `markdown.mode` option

3 files changed, 128 insertions, 0 deletions

diff --git a/packages/markdown/remark/test/components.test.js b/packages/markdown/remark/test/components.test.js
new file mode 100644
index 000000000..0f3418c24
--- /dev/null
+++ b/packages/markdown/remark/test/components.test.js
@@ -0,0 +1,62 @@
+import { renderMarkdown } from '../dist/index.js';
+import chai from 'chai';
+
+describe('components', () => {
+	it('should be able to serialize string', async () => {
+		const { code } = await renderMarkdown(`<Component str="cool!" />`, {});
+
+		chai.expect(code).to.equal(`<Component str="cool!" />`);
+	});
+
+	it('should be able to serialize boolean attribute', async () => {
+		const { code } = await renderMarkdown(`<Component bool={true} />`, {});
+
+		chai.expect(code).to.equal(`<Component bool={true} />`);
+	});
+
+	it('should be able to serialize array', async () => {
+		const { code } = await renderMarkdown(`<Component prop={["a", "b", "c"]} />`, {});
+
+		chai.expect(code).to.equal(`<Component prop={["a", "b", "c"]} />`);
+	});
+
+	it('should be able to serialize object', async () => {
+		const { code } = await renderMarkdown(`<Component prop={{ a: 0, b: 1, c: 2 }} />`, {});
+
+		chai.expect(code).to.equal(`<Component prop={{ a: 0, b: 1, c: 2 }} />`);
+	});
+
+	it('should be able to serialize empty attribute', async () => {
+		const { code } = await renderMarkdown(`<Component empty />`, {});
+
+		chai.expect(code).to.equal(`<Component empty />`);
+	});
+
+	// Notable omission: shorthand attribute
+
+	it('should be able to serialize spread attribute', async () => {
+		const { code } = await renderMarkdown(`<Component {...spread} />`, {});
+
+		chai.expect(code).to.equal(`<Component {...spread} />`);
+	});
+
+	it('should allow client:* directives', async () => {
+		const { code } = await renderMarkdown(`<Component client:load />`, {});
+
+		chai.expect(code).to.equal(`<Component client:load />`);
+	});
+
+	it('should normalize children', async () => {
+		const { code } = await renderMarkdown(`<Component bool={true}>Hello world!</Component>`, {});
+
+		chai.expect(code).to.equal(`<Fragment>\n<Component bool={true}>Hello world!</Component>\n</Fragment>`);
+	});
+
+	it('should allow markdown without many spaces', async () => {
+		const { code } = await renderMarkdown(`<Component>
+# Hello world!
+</Component>`, {});
+
+		chai.expect(code).to.equal(`<Fragment>\n<Component><h1 id="hello-world">Hello world!</h1></Component>\n</Fragment>`);
+	});
+});
diff --git a/packages/markdown/remark/test/expressions.test.js b/packages/markdown/remark/test/expressions.test.js
new file mode 100644
index 000000000..bcc95cbed
--- /dev/null
+++ b/packages/markdown/remark/test/expressions.test.js
@@ -0,0 +1,40 @@
+import { renderMarkdown } from '../dist/index.js';
+import chai from 'chai';
+
+describe('expressions', () => {
+	it('should be able to serialize bare expession', async () => {
+		const { code } = await renderMarkdown(`{a}`, {});
+
+		chai.expect(code).to.equal(`{a}`);
+	});
+
+	it('should be able to serialize expression inside component', async () => {
+		const { code } = await renderMarkdown(`<Component>{a}</Component>`, {});
+
+		chai.expect(code).to.equal(`<Fragment>\n<Component>{a}</Component>\n</Fragment>`);
+	});
+
+	it('should be able to serialize expression inside markdown', async () => {
+		const { code } = await renderMarkdown(`# {frontmatter.title}`, {});
+
+		chai.expect(code).to.equal(`<h1 id={$$slug(\`\${frontmatter.title}\`)}>{frontmatter.title}</h1>`);
+	});
+
+	it('should be able to serialize complex expression inside markdown', async () => {
+		const { code } = await renderMarkdown(`# Hello {frontmatter.name}`, {});
+
+		chai.expect(code).to.equal(`<h1 id={$$slug(\`Hello \${frontmatter.name}\`)}>Hello {frontmatter.name}</h1>`);
+	});
+
+	it('should be able to serialize complex expression with markup inside markdown', async () => {
+		const { code } = await renderMarkdown(`# Hello <span>{frontmatter.name}</span>`, {});
+
+		chai.expect(code).to.equal(`<h1 id={$$slug(\`Hello \${frontmatter.name}\`)}>Hello <span>{frontmatter.name}</span></h1>`);
+	});
+
+	it('should be able to serialize function expression', async () => {
+		const { code } = await renderMarkdown(`{frontmatter.list.map(item => <p id={item}>{item}</p>)}`	, {});
+
+		chai.expect(code).to.equal(`{frontmatter.list.map(item => <p id={item}>{item}</p>)}`);
+	})
+});
diff --git a/packages/markdown/remark/test/plugins.test.js b/packages/markdown/remark/test/plugins.test.js
new file mode 100644
index 000000000..4954047b5
--- /dev/null
+++ b/packages/markdown/remark/test/plugins.test.js
@@ -0,0 +1,26 @@
+import { renderMarkdown } from '../dist/index.js';
+import chai from 'chai';
+
+import { fileURLToPath } from 'node:url';
+
+describe('plugins', () => {
+	// https://github.com/withastro/astro/issues/3264
+	it('should be able to get file path when passing fileURL', async () => {
+		let context;
+		await renderMarkdown(`test`, {
+			fileURL: new URL('virtual.md', import.meta.url),
+			remarkPlugins: [
+				function () {
+					const transformer = (tree, file) => {
+						context = file;
+					};
+
+					return transformer;
+				}
+			]
+		});
+
+		chai.expect(typeof context).to.equal('object');
+		chai.expect(context.path).to.equal(fileURLToPath(new URL('virtual.md', import.meta.url)));
+	});
+})